Merge pull request 'Assignment 7' (#4) from Assignment-7 into master

Reviewed-on: #4
2024-07-08 11:19:48 +02:00 · 2024-07-08 11:19:48 +02:00 · 65ce338921
commit 65ce338921
parent d7c5c2b778 18cc163954
36 changed files with 3320 additions and 26 deletions
--- a/.gitignore
+++ b/.gitignore
@ -24,7 +24,6 @@ dist/
 downloads/
 eggs/
 .eggs/
 lib/
 lib64/
 parts/
 sdist/
--- a/Hands-on/LICENSE
+++ b/Hands-on/LICENSE
@ -0,0 +1,674 @@
                    GNU GENERAL PUBLIC LICENSE
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    under certain conditions; type `show c' for details.
 The hypothetical commands `show w' and `show c' should show the appropriate
 parts of the General Public License.  Of course, your program's commands
 might be different; for a GUI interface, you would use an "about box".
  You should also get your employer (if you work as a programmer) or school,
 if any, to sign a "copyright disclaimer" for the program, if necessary.
 For more information on this, and how to apply and follow the GNU GPL, see
 <https://www.gnu.org/licenses/>.
  The GNU General Public License does not permit incorporating your program
 into proprietary programs.  If your program is a subroutine library, you
 may consider it more useful to permit linking proprietary applications with
 the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
 <https://www.gnu.org/licenses/why-not-lgpl.html>.
--- a/Hands-on/README.md
+++ b/Hands-on/README.md
@ -0,0 +1,75 @@
 # Signature Relay for firmware
 Documentation of the Assignment 7 in Systems Security at Ruhr-Universität Bochum.
 This is a program, that uses a TEE to build a signature relay to sign firmware with a master key.
 For more informationm, read the [project description](doc/abgabe.pdf).
 We recommend viewing the [repository]("https://git.pfzetto.de/RubNoobs/Systemsicherheit/src/branch/master/Assignment 7 - SGX Hands-on") we worked on together at.
 ## Requirements
 You will need the latest version of OpenSSL.
 Execute the following command inside the  src directory to automatically meet all requirements. 
 ```bash
 $ ./setup
 ```
 ## Compiling
 This project can be compiled for simulation environments or directly on the hardware.
 1. **Simulated environment**
 In the src directory type the command
 ```bash
 $ make SGX_MODE=SIM
 ```
 2. **Hardware**
 In the src directory type the command
 ```bash
 $ make
 ```
 That creates all the necessary objects and binaries to execute. 
 The executable binary will be `src/signatureproxy`.
 ## Running
 ## Running story
 To execute an example usage of the project, execute `./simulate` in src directory. 
 Note, that this will only work, if you sucessfully compiled the project.
 ## Manual Usage
 ### Setup
 Go to the `src` directory.
 Initialize the Enclave keypair by executing:
 `./signatureproxy proxysetup -pkey <sealed_proxy_key.bin> > <proxy_public_key.pem>` 
 ### Sign
 1. Create employee signature using `./signatureproxy employee -firm <firmware.bin> -ekey <employee_privat_key.pem> > <employee_signature.der>`
   This step can also be done using OpenSSL: `openssl dgst -sha256 -sign <employee_private_key.pem> -out <employee_signature.der> -in <firmware.bin>`
 2. Use the signature proxy to resign the firmware using `./signatureproxy proxy -pkey <sealed_proxy_key.bin> -epub <employee_public_key.der> -firm <firmware.bin> > <proxy_signature.der>`
   The enclave verifies the employee signature and signs the firmware if the signature is valid.
 3. Verify signature using `cat <proxy_signature.der> | ./signatureproxy embedded -firm <firmware.bin> -ppub <proxy_public_key.pem>` 
   This step can also be done using OpenSSL: `openssl dgst -sha256 -verify <proxy_public_key.pem> -signature <proxy-signature.der> <firmware.bin>`
 ## License
 Everything we did ourselves is licensed under the [GNU GPLv3 License](./LICENSE)
 ## Contributors
 - Benjamin Haschka
 - Sascha Tommasone
 - Paul Zinselmeyer
--- a/Hands-on/doc/abgabe.pdf
+++ b/Hands-on/doc/abgabe.pdf
--- a/Hands-on/doc/abgabe.typ
+++ b/Hands-on/doc/abgabe.typ
@ -0,0 +1,131 @@
 #let conf(
  title: none, 
  assignmentno: none,
  authors: (),
  doc
 ) = {
  set page(
    paper: "a4",
    header: [
    #set text(size: 9pt)
    #grid(
      columns: 3,
      gutter: 1fr,
      rows: 1,
      align(left + horizon, smallcaps(title)),
      align(center + horizon, "Assignment-" + assignmentno),
      grid(
        align: right,
        columns: 1,
        rows: authors.len(),
        row-gutter: 3pt,
        ..authors.map(author => [
          #author
        ])
      )
    )
    #line(length: 100%)
    ],
    footer: context [
      #line(length: 100%)
      #set align(center)
      #counter(page).display(
        "1 / 1",
        both: true
      )
    ],
  )
  set text(
    size: 11pt,
    font: "DejaVu Serif"
  )
  doc
 }
 #show: doc => conf(
  title: "System Security",
  assignmentno: "7",
  authors: (
    "Benjamin Haschka",
    "Sascha Tommasone",
    "Paul Zinselmeyer"
  ),
  doc
 )
 = Firmware Signatur-Relay in einer TEE
 Das Program hat den Zweck, Signaturen die von einzelnen Nutzern über eine Firmware gemacht werden, mit einem permanenten Produktions-Key zu maskieren, ohne, dass der Nutzer diesen kennt.
 Dabei wird eine Encalve als Signatur-Relay verwendet.
 Die Enclave kann Signaturen über Daten mit einem festen Satz an öffentlichen Schlüsseln, die vertrauenswürdig sind, verifizieren.
 Wenn die Signatur gültig ist, entfernt die Enclave die Signatur und erzeugt eine eigene Signatur mit dem Produktions-Key.
 #grid(
  columns: 2,
  figure(
    image("correct-signature.png"),
    caption: "Valid Signature"
  ),
  figure(
    image("unknown-signature.png"),
    caption: "Invalid Signature"
  )
 )
 Diese Signatur kann dann mit dem öffentlichen Schlüssel der Enclave, der von außen angefragt werden kann, überprüft werden.
 Damit kann der Nutzer seine eigene Signatur mit der Signatur der Enclave maskieren.
 Der Schlüssel ist dabei den Nutzern nie bekannt.
 Sie haben den Schlüssel nur versiegelt und können ihn der Enclave geben, die den Schlüssel dann entsiegeln und in der vertrauenswürdigen Umgebung verwenden kann.
 == Szenario
 In diesem Szenario wird ein Unternehmen betrachtet, das Embedded Geräte produziert.
 Für die Geräte sollen regelmäßig Updates für die Firmware veröffentlicht werden.
 Diese Firmware muss mit einem permanenten Key signiert werden, der in der Produktion der Geräte fest codiert wird.
 Ist die Signatur nicht vorhanden, lädt keines der Geräte das Update.
 Mitarbeitende, die die Firmware hochladen wollen, müssen also die implementierte Firmware mit dem Produktions-Key signieren.
 Wenn sie den Produktions-Key besitzen, bringt das gewissen risiken, z.B.:
 - Mitarbeitende können (absichtilich oder nicht) den Schlüssel veröffentlichen
 - Mitarbeitende, die nicht mehr in dem Unternehmen arbeiten, können den Key für schlechte Zwecke missbrauchen
 Es ist also sinnvoll, wenn die Mitarbeitende den Key nicht kennen. Dazu kann das beschriebene Signatur-Relay verwendet werden.
 Die Mitarbeitenden signieren die Firmware vorerst mit ihrem eigenen Key.
 Diese Keys sind in das Relay als trusted Keys eingebunden.
 Anschließend kann der Mitarbeitende die selbst-signierte Firmware an das Signatur-Relay senden.
 Das Relay prüft dann die Gültigkeit der Signatur und schickt, falls gültig, eine eigene Signatur über die Firmware zurück.
 Damit kann dann der Mitarbeitende die Firmware an die Embedded Geräte senden, bei Gültigkeit die neue Firmware laden können.
 Falls ein Mitarbeitender den eigenen Schlüssel verlieren oder veröffentlichen sollte, besteht in dem Fall auch nicht das Problem, dass der Produktionsschlüssel ungültig wird.
 Es kann einfach der Schlüssel des Mitarbeitenden von der Liste der trusted Keys zurückgezogen werden. 
 Zudem ist es wichtig, dass keine bösartigen Programme auf den Systemen der Mitarbeitenden den Signaturprozess mitbekommen oder gar verändern können.
 Aus diesen Gründen ist es in diesem Szenario wichtig, dass das Relay mit all seinen Funktionen besonders geschützt ist.
 Dementsprechend sollte es in einer Enclave laufen.
 == Details
 1. *Key Management*
 Das Key Management wird mit der eingebauten `seal` Funktion der Encalve gemacht.
 Dabei kann jeder Nutzer eine versiegelte Kopie des Schlüssels behalten, da er damit nichts anfangen kann.
 Erst, wenn der Schlüssel in die Enclave kommt und entsiegelt wird, kann der Schlüssel verwendet werden.
 2. *Signatur Erstellung*
 Die Enclave bietet eine Schnittstelle für Signaturen mit ECDSA an. 
 Dabei wird die Kurve secp256k1 verwendet.
 == Vorteile
 Dieses Programm bietet einige Vorteile, unter anderem:
 - Nutzern unbekannter Hauptschlüssel
 - Vereinfacht das Zurückziehen der Schlüssel
 - Sicherheit der Gültigkeit der Firmware
--- a/Hands-on/doc/correct-signature.png
+++ b/Hands-on/doc/correct-signature.png
--- a/Hands-on/doc/unknown-signature.png
+++ b/Hands-on/doc/unknown-signature.png
--- a/Hands-on/employee_keys/alice_private.pem
+++ b/Hands-on/employee_keys/alice_private.pem
@ -0,0 +1,5 @@
 -----BEGIN EC PRIVATE KEY-----
 MHcCAQEEIH0KXxaw/nRzJU5evlEJQrciYUtfJ16PILWtlA5KKh/koAoGCCqGSM49
 AwEHoUQDQgAEduVQXmH1K+ocSSnv0l9PKdC2+xxPQrVyABAYGk+jlo2hugpH8aWk
 nfR9cTTOLy6T7ASx3a22S6DftcTz+aZYsg==
 -----END EC PRIVATE KEY-----
--- a/Hands-on/employee_keys/alice_public.pem
+++ b/Hands-on/employee_keys/alice_public.pem
@ -0,0 +1,4 @@
 -----BEGIN PUBLIC KEY-----
 MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEduVQXmH1K+ocSSnv0l9PKdC2+xxP
 QrVyABAYGk+jlo2hugpH8aWknfR9cTTOLy6T7ASx3a22S6DftcTz+aZYsg==
 -----END PUBLIC KEY-----
--- a/Hands-on/employee_keys/bob_private.pem
+++ b/Hands-on/employee_keys/bob_private.pem
@ -0,0 +1,5 @@
 -----BEGIN EC PRIVATE KEY-----
 MHcCAQEEICV85UuIaBKQ9yisKQne4i4E3HjB4KysQdqnhnrX8LtLoAoGCCqGSM49
 AwEHoUQDQgAE7iz5LravULyrYQgu9rIX7iyUQdi7GTJ63Af/DlIrcpy7UbpWdh0O
 h5LGlfaMgQ4pq9ORF8+K3LCUYMqUtS+EjA==
 -----END EC PRIVATE KEY-----
--- a/Hands-on/employee_keys/bob_public.pem
+++ b/Hands-on/employee_keys/bob_public.pem
@ -0,0 +1,4 @@
 -----BEGIN PUBLIC KEY-----
 MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE7iz5LravULyrYQgu9rIX7iyUQdi7
 GTJ63Af/DlIrcpy7UbpWdh0Oh5LGlfaMgQ4pq9ORF8+K3LCUYMqUtS+EjA==
 -----END PUBLIC KEY-----
--- a/Hands-on/employee_keys/oskar_private.pem
+++ b/Hands-on/employee_keys/oskar_private.pem
@ -0,0 +1,5 @@
 -----BEGIN EC PRIVATE KEY-----
 MHcCAQEEINtBCS3yRqZNxO+RPdV2618QVDfhqmXheAQ9G3hMmxLyoAoGCCqGSM49
 AwEHoUQDQgAEzkxblxb/svE5kta/IdNs0NQgDk7CO5nBs/LVeiJDz2iiFwERK6u7
 oNj36jvwppi3jFmHp7nFNZEzim45DcY7vA==
 -----END EC PRIVATE KEY-----
--- a/Hands-on/employee_keys/oskar_public.pem
+++ b/Hands-on/employee_keys/oskar_public.pem
@ -0,0 +1,4 @@
 -----BEGIN PUBLIC KEY-----
 MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEzkxblxb/svE5kta/IdNs0NQgDk7C
 O5nBs/LVeiJDz2iiFwERK6u7oNj36jvwppi3jFmHp7nFNZEzim45DcY7vA==
 -----END PUBLIC KEY-----
--- a/Hands-on/flake.lock
+++ b/Hands-on/flake.lock
@ -0,0 +1,27 @@
 {
  "nodes": {
    "nixpkgs": {
      "locked": {
        "lastModified": 1719838683,
        "narHash": "sha256-Zw9rQjHz1ilNIimEXFeVa1ERNRBF8DoXDhLAZq5B4pE=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "d032c1a6dfad4eedec7e35e91986becc699d7d69",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixos-24.05",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "root": {
      "inputs": {
        "nixpkgs": "nixpkgs"
      }
    }
  },
  "root": "root",
  "version": 7
 }
--- a/Hands-on/flake.nix
+++ b/Hands-on/flake.nix
@ -0,0 +1,50 @@
 {
    description = "SignatureProxy SGX Demo";
    inputs = {
        nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
    };
    outputs = { self, nixpkgs, ... }: 
    let
        lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
        version = builtins.substring 0 8 lastModifiedDate;
        nixpkgsFor = system: import nixpkgs { inherit system; overlays = [ self.overlay ]; };
    in
    {
        overlay = final: prev: with final; {
            signatureProxy = stdenv.mkDerivation {
                pname = "SignatureProxy";
                inherit version;
                src = ./src;
                buildPhase = ''
                    make
                '';
                installPhase = ''
                    mkdir -p $out/bin
                    cp signatureproxy $out/bin
                    cp enclave.signed.so $out/bin
                '';
                nativeBuildInputs = with pkgs; [
                    clang
                    glibc
                    sgx-sdk
                    openssl.dev
                    pkg-config
                    which
                ];
                env = {
                    SGX_SDK = pkgs.sgx-sdk;
                    SGX_MODE = "SIM";
                };
            };
        };
        defaultPackage."x86_64-linux" = (nixpkgsFor "x86_64-linux").signatureProxy;
    };
 }
--- a/Hands-on/src/Makefile
+++ b/Hands-on/src/Makefile
@ -0,0 +1,249 @@
 #
 # Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 #
 #   * Redistributions of source code must retain the above copyright
 #     notice, this list of conditions and the following disclaimer.
 #   * Redistributions in binary form must reproduce the above copyright
 #     notice, this list of conditions and the following disclaimer in
 #     the documentation and/or other materials provided with the
 #     distribution.
 #   * Neither the name of Intel Corporation nor the names of its
 #     contributors may be used to endorse or promote products derived
 #     from this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 #
 ######## SGX SDK Settings ########
 SGX_SDK ?= /opt/intel/sgxsdk
 SGX_MODE ?= HW
 SGX_ARCH ?= x64
 SGX_DEBUG ?= 1
 ifeq ($(shell getconf LONG_BIT), 32)
 	SGX_ARCH := x86
 else ifeq ($(findstring -m32, $(CCFLAGS)), -m32)
 	SGX_ARCH := x86
 endif
 ifeq ($(SGX_ARCH), x86)
 	SGX_COMMON_CFLAGS := -m32
 	SGX_LIBRARY_PATH := $(SGX_SDK)/lib
 	SGX_ENCLAVE_SIGNER := $(SGX_SDK)/bin/x86/sgx_sign
 	SGX_EDGER8R := $(SGX_SDK)/bin/x86/sgx_edger8r
 else
 	SGX_COMMON_CFLAGS := -m64
 	SGX_LIBRARY_PATH := $(SGX_SDK)/lib64
 	SGX_ENCLAVE_SIGNER := $(SGX_SDK)/bin/x64/sgx_sign
 	SGX_EDGER8R := $(SGX_SDK)/bin/x64/sgx_edger8r
 endif
 ifeq ($(SGX_DEBUG), 1)
 ifeq ($(SGX_PRERELEASE), 1)
 $(error Cannot set SGX_DEBUG and SGX_PRERELEASE at the same time!!)
 endif
 endif
 ifeq ($(SGX_DEBUG), 1)
        SGX_COMMON_CFLAGS += -O0 -g
 else
        SGX_COMMON_CFLAGS += -O2
 endif
 ######## App Settings ########
 ifneq ($(SGX_MODE), HW)
 	Urts_Library_Name := sgx_urts_sim
 else
 	Urts_Library_Name := sgx_urts
 endif
 App_C_Files := app/main.c app/proxy.c app/proxysetup.c app/employee.c app/util.c app/embedded_device.c
 App_Include_Paths := -IInclude -Iapp -I$(SGX_SDK)/include -I/usr/local/openssl-3.3.1/include
 App_C_Flags := $(SGX_COMMON_CFLAGS) -fPIC -Wno-attributes $(App_Include_Paths)
 # Three configuration modes - Debug, prerelease, release
 #   Debug - Macro DEBUG enabled.
 #   Prerelease - Macro NDEBUG and EDEBUG enabled.
 #   Release - Macro NDEBUG enabled.
 ifeq ($(SGX_DEBUG), 1)
        App_C_Flags += -DDEBUG -UNDEBUG -UEDEBUG
 else ifeq ($(SGX_PRERELEASE), 1)
        App_C_Flags += -DNDEBUG -DEDEBUG -UDEBUG
 else
        App_C_Flags += -DNDEBUG -UEDEBUG -UDEBUG
 endif
 OPENSSL := -Wl,-Bstatic -L/usr/local/openssl-3.3.1/lib64 -lssl -lcrypto -Wl,-Bdynamic -ldl
 App_Link_Flags := $(SGX_COMMON_CFLAGS) -L$(SGX_LIBRARY_PATH) -l$(Urts_Library_Name) -lpthread -lsgx_urts $(OPENSSL)
 ifneq ($(SGX_MODE), HW)
 	App_Link_Flags += -lsgx_uae_service_sim
 else
 	App_Link_Flags += -lsgx_uae_service
 endif
 App_C_Objects := $(App_C_Files:.c=.o)
 App_Name := signatureproxy
 ######## Enclave Settings ########
 ifneq ($(SGX_MODE), HW)
 	Trts_Library_Name := sgx_trts_sim
 	Service_Library_Name := sgx_tservice_sim
 else
 	Trts_Library_Name := sgx_trts
 	Service_Library_Name := sgx_tservice
 endif
 Crypto_Library_Name := sgx_tcrypto
 Enclave_C_Files := enclave/enclave.c
 Enclave_Include_Paths := -IInclude -Ienclave -I$(SGX_SDK)/include -I$(SGX_SDK)/include/tlibc -I$(SGX_SDK)/include/libcxx
 CC_BELOW_4_9 := $(shell expr "`$(CC) -dumpversion`" \< "4.9")
 ifeq ($(CC_BELOW_4_9), 1)
 	Enclave_C_Flags := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -ffunction-sections -fdata-sections -fstack-protector
 else
 	Enclave_C_Flags := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -ffunction-sections -fdata-sections -fstack-protector-strong
 endif
 Enclave_C_Flags += $(Enclave_Include_Paths)
 # To generate a proper enclave, it is recommended to follow below guideline to link the trusted libraries:
 #    1. Link sgx_trts with the `--whole-archive' and `--no-whole-archive' options,
 #       so that the whole content of trts is included in the enclave.
 #    2. For other libraries, you just need to pull the required symbols.
 #       Use `--start-group' and `--end-group' to link these libraries.
 # Do NOT move the libraries linked with `--start-group' and `--end-group' within `--whole-archive' and `--no-whole-archive' options.
 # Otherwise, you may get some undesirable errors.
 Enclave_Link_Flags := $(SGX_COMMON_CFLAGS) -Wl,--no-undefined -nostdlib -nodefaultlibs -nostartfiles -L$(SGX_LIBRARY_PATH) \
 	-Wl,--whole-archive -l$(Trts_Library_Name) -Wl,--no-whole-archive \
 	-Wl,--start-group -lsgx_tstdc -lsgx_tcxx -l$(Crypto_Library_Name) -l$(Service_Library_Name) -Wl,--end-group \
 	-Wl,-Bstatic -Wl,-Bsymbolic -Wl,--no-undefined \
 	-Wl,-pie,-eenclave_entry -Wl,--export-dynamic  \
 	-Wl,--defsym,__ImageBase=0 -Wl,--gc-sections   \
 	-Wl,--version-script=enclave/enclave.lds \
 Enclave_C_Objects := $(Enclave_C_Files:.c=.o)
 Enclave_Name := enclave.so
 Signed_Enclave_Name := enclave.signed.so
 Enclave_Config_File := enclave/enclave.config.xml
 ifeq ($(SGX_MODE), HW)
 ifeq ($(SGX_DEBUG), 1)
 	Build_Mode = HW_DEBUG
 else ifeq ($(SGX_PRERELEASE), 1)
 	Build_Mode = HW_PRERELEASE
 else
 	Build_Mode = HW_RELEASE
 endif
 else
 ifeq ($(SGX_DEBUG), 1)
 	Build_Mode = SIM_DEBUG
 else ifeq ($(SGX_PRERELEASE), 1)
 	Build_Mode = SIM_PRERELEASE
 else
 	Build_Mode = SIM_RELEASE
 endif
 endif
 .PHONY: all run
 ifeq ($(Build_Mode), HW_RELEASE)
 all: .config_$(Build_Mode)_$(SGX_ARCH) $(App_Name) $(Enclave_Name)
 	@echo "The project has been built in release hardware mode."
 	@echo "Please sign the $(Enclave_Name) first with your signing key before you run the $(App_Name) to launch and access the enclave."
 	@echo "To sign the enclave use the command:"
 	@echo "   $(SGX_ENCLAVE_SIGNER) sign -key <your key> -enclave $(Enclave_Name) -out <$(Signed_Enclave_Name)> -config $(Enclave_Config_File)"
 	@echo "You can also sign the enclave using an external signing tool."
 	@echo "To build the project in simulation mode set SGX_MODE=SIM. To build the project in prerelease mode set SGX_PRERELEASE=1 and SGX_MODE=HW."
 else
 all: .config_$(Build_Mode)_$(SGX_ARCH) $(App_Name) $(Signed_Enclave_Name)
 ifeq ($(Build_Mode), HW_DEBUG)
 	@echo "The project has been built in debug hardware mode."
 else ifeq ($(Build_Mode), SIM_DEBUG)
 	@echo "The project has been built in debug simulation mode."
 else ifeq ($(Build_Mode), HW_PRERELEASE)
 	@echo "The project has been built in pre-release hardware mode."
 else ifeq ($(Build_Mode), SIM_PRERELEASE)
 	@echo "The project has been built in pre-release simulation mode."
 else
 	@echo "The project has been built in release simulation mode."
 endif
 endif
 run: all
 ifneq ($(Build_Mode), HW_RELEASE)
 	@$(CURDIR)/$(App_Name)
 	@echo "RUN  =>  $(App_Name) [$(SGX_MODE)|$(SGX_ARCH), OK]"
 endif
 ######## App Objects ########
 app/enclave_u.c: $(SGX_EDGER8R) enclave/enclave.edl
 	@cd app && $(SGX_EDGER8R) --untrusted ../enclave/enclave.edl --search-path ../enclave --search-path $(SGX_SDK)/include
 	@echo "GEN  =>  $@"
 app/enclave_u.o: app/enclave_u.c
 	@$(CC) $(App_C_Flags) -c $< -o $@
 	@echo "CC   <=  $<"
 app/%.o: app/%.c
 	@$(CC) $(App_C_Flags) -c $< -o $@
 	@echo "CC  <=  $<"
 $(App_Name): app/enclave_u.o $(App_C_Objects)
 	@$(CC) $^ -o $@ $(App_Link_Flags)
 	@echo "LINK =>  $@"
 .config_$(Build_Mode)_$(SGX_ARCH):
 	@rm -f .config_* $(App_Name) $(Enclave_Name) $(Signed_Enclave_Name) $(App_C_Objects) app/enclave_u.* $(Enclave_C_Objects) enclave/enclave_t.*
 	@touch .config_$(Build_Mode)_$(SGX_ARCH)
 ######## Enclave Objects ########
 enclave/enclave_t.c: $(SGX_EDGER8R) enclave/enclave.edl
 	@cd enclave && $(SGX_EDGER8R) --trusted ../enclave/enclave.edl --search-path ../enclave --search-path $(SGX_SDK)/include
 	@echo "GEN  =>  $@"
 enclave/enclave_t.o: enclave/enclave_t.c
 	@$(CC) $(Enclave_C_Flags) -c $< -o $@
 	@echo "CC   <=  $<"
 enclave/%.o: enclave/%.c
 	@$(CC) $(Enclave_C_Flags) -c $< -o $@
 	@echo "CC  <=  $<"
 $(Enclave_Name): enclave/enclave_t.o $(Enclave_C_Objects)
 	@$(CC) $^ -o $@ $(Enclave_Link_Flags)
 	@echo "LINK =>  $@"
 $(Signed_Enclave_Name): $(Enclave_Name)
 	@$(SGX_ENCLAVE_SIGNER) sign -key enclave/enclave_private.pem -enclave $(Enclave_Name) -out $@ -config $(Enclave_Config_File)
 	@echo "SIGN =>  $@"
 .PHONY: clean
 clean:
 	@rm -f .config_* $(App_Name) $(Enclave_Name) $(Signed_Enclave_Name) $(App_C_Objects) app/enclave_u.* $(Enclave_C_Objects) enclave/enclave_t.*
--- a/Hands-on/src/app/embedded_device.c
+++ b/Hands-on/src/app/embedded_device.c
@ -0,0 +1,143 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include "util.h"
 #include <openssl/sha.h>
 #include <openssl/ec.h>
 #include <openssl/bn.h>
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/pem.h>
 #include <openssl/core_names.h>
 #include "embedded_device.h"
 #define BUFSIZE 16384
 typedef struct {
    uint8_t *firmware_path;
    uint8_t *public_key_path;
 } embedded_device_args;
 char *embedded_device_syntax(void) {
    return
        "embedded            mock up implementation of a embedded device\n"
        "    -ppub  <path>   file path of the PEM encoded public key of the proxy\n"
        "    -firm  <path>   path of to firmware binary\n";
 }
 /*
 * read secp256r1 public key and return it as EVP_PKEY*
 */
 static EVP_PKEY *read_public_key(char *public_key_file_path, EVP_PKEY **key) {
    if(public_key_file_path == NULL) {
        fprintf(stderr, "public_key_file_path is a null pointer!\n");
        return NULL;
    }
    FILE *fd = fopen(public_key_file_path, "rb");
    if(fd == NULL) {
        fprintf(stderr, "failed to open public key file!\n");
        return NULL;
    }
    *key = PEM_read_PUBKEY(fd, key, NULL, NULL);
    fclose(fd);
    return *key;
 }
 /*
 * hash the firmware
 */
 static void hash_firmware(uint8_t *firmware_path, EVP_MD_CTX **ctx) {
    if(firmware_path == NULL) {
        fprintf(stderr, "firmware_path is a null pointer!\n");
        return;
    }
    FILE *fd = fopen(firmware_path, "rb");
    if(fd == NULL) {
        fprintf(stderr, "failed to open firmware!\n");
        goto exit;
    }
    size_t size;
    uint8_t buf[BUFSIZE];
    while((size = fread(buf, 1, BUFSIZE, fd)) != 0) {
        EVP_DigestVerifyUpdate(*ctx, buf, size);
    }
    exit: fclose(fd);
 }
 int handle_embedded_device(int argc, char **argv) {
    uint8_t status = EXIT_SUCCESS;
    embedded_device_args args = {
        .firmware_path = NULL,
        .public_key_path = NULL
    };
    // parse parameters
    for(int i = 0; i < argc; i += 2) {
        if((strcmp(argv[i], "-ppub") == 0) && (argc - i >= 2)) {
            args.public_key_path = argv[i+1];
        } else if((strcmp(argv[i], "-firm") == 0) && (argc - i >= 2)) {
            args.firmware_path = argv[i+1];
        } else {
            syntax_exit();
        }
    }
    // handle invalid parameters
    if((args.firmware_path == NULL) || (args.public_key_path == NULL)) {
        fprintf(stderr, "failed to parse arguments");
        exit(EXIT_FAILURE);
    }
    // read the public key of the enclave
    // normally, key would be hardcoded during production
    EVP_PKEY *key = NULL;
    if(read_public_key(args.public_key_path, &key) == NULL) {
        fprintf(stderr, "failed to import public key");
        status = EXIT_FAILURE;
        goto clean;
    }
    // initialize the context
    EVP_MD_CTX *ctx = EVP_MD_CTX_new();
    if (EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, key) != 1) {
        fprintf(stderr, "failed to initialize context\n");
        status = EXIT_FAILURE;
        goto clean;
    }
    // read the firmwares signature
    uint8_t signature[BUFSIZE] = {0};
    size_t signature_size = read(0, signature, BUFSIZE);
    if(signature_size < 70) {
        fprintf(stderr, "failed to read firmware signature\n");
        status = EXIT_FAILURE;
        goto clean;
    }
    // hash the firmware and verify the signature
    hash_firmware(args.firmware_path, &ctx);
    if (EVP_DigestVerifyFinal(ctx, signature, signature_size) != 1) {
        fprintf(stderr, "failed to verify firmware signature or signature invalid\n");
        status = EXIT_FAILURE;
    }else {
        printf("Firmware is valid! Update starts in 5 4 3...\n");
    }
    // cleanup
    clean: ;
    if(key != NULL)
        EVP_PKEY_free(key);
    if(ctx != NULL)
        EVP_MD_CTX_free(ctx);
    return status;
 }
--- a/Hands-on/src/app/embedded_device.h
+++ b/Hands-on/src/app/embedded_device.h
@ -0,0 +1,23 @@
 #ifndef EMBEDDED_DEVICE_H
 #define EMBEDDED_DEVICE_H
 #include <stdint.h>
 /*
 * @brief getter for embedded subcommand syntax string
 *
 * @returns null-terminated syntax string
 */
 char *embedded_device_syntax(void);
 /*
 * @brief CLI implementation for the "embedded" subcommand
 *
 * @param argc number of arguments with command and subcommand stripped
 * @param argv arguments with command and subcommand stripped
 *
 * @returns 0 on success, else error with output on stderr
 */
 int handle_embedded_device(int argc, char **argv);
 #endif
--- a/Hands-on/src/app/employee.c
+++ b/Hands-on/src/app/employee.c
@ -0,0 +1,135 @@
 #include <errno.h>
 #include <sgx_urts.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "employee.h"
 #include "util.h"
 #include <openssl/core_names.h>
 #include <openssl/evp.h>
 #include <openssl/pem.h>
 #define HASH_BYTES 32
 #define HASH_CHUNK_BYTES 32
 #define KEY_BYTES 32
 struct EmployeeArgs {
    char* key_path;
    char* firmware_path;
 };
 char* employee_syntax(void) {
    return
        "employee            mock up implementation of the employee binary\n"
        "                    outputs signature on stdout\n"
        "                    WARNING: output is in binary format, may mess up terminal\n"
        "    -ekey <path>    file path of the PEM encoded private key of the employee\n"
        "    -firm <path>    path of the firmware\n";
 }
 int handle_employee(int argc, char** argv) {
    struct EmployeeArgs args = {
        NULL,
        NULL
    };
    FILE* key_file = NULL;
    uint8_t* firmware_buf;
    size_t firmware_len;
    EVP_PKEY* key = NULL;
    EVP_MD_CTX *mdctx = NULL;
    size_t sig_len;
    unsigned char* sig = NULL;
    /*
     * Parse Input
     */
    int i = 0;
    while(i < argc) {
        if(strcmp(argv[i], "-ekey")==0 && argc-i >=2){
            args.key_path = argv[i+1];
            i += 2;
        }else if(strcmp(argv[i], "-firm")==0 && argc-i >=2){
            args.firmware_path = argv[i+1];
            i += 2;
        }else
            syntax_exit();
    }
    if(args.key_path == NULL)
        syntax_exit();
    /*
     * Load Signing Key
     */
    key_file = fopen(args.key_path, "rb");
    if(key_file == NULL){
        perror("Error opening key file");
        exit (EXIT_FAILURE);
    }
    key = PEM_read_PrivateKey(key_file, &key, NULL, NULL);
    if(key == NULL) {
        fprintf(stderr, "failed to read key\n");
        exit (EXIT_FAILURE);
    }
    fclose(key_file);
    /*
     * Sign Firmware
     */
    mdctx = EVP_MD_CTX_new();
    if (EVP_DigestSignInit(mdctx, NULL, EVP_sha256(), NULL, key) != 1) {
        fprintf(stderr, "Message digest initialization failed.\n");
        exit (EXIT_FAILURE);
    }
    if (load_file(args.firmware_path, &firmware_buf, &firmware_len) != 0) {
        fprintf(stderr, "failed to read firmware\n");
        exit (EXIT_FAILURE);
    }
    if (EVP_DigestSignUpdate(mdctx, firmware_buf, firmware_len) != 1) {
        printf("Message digest update failed.\n");
        exit(EXIT_FAILURE);
    }
    free(firmware_buf);
    // call with empty sig to get length
    if (EVP_DigestSignFinal(mdctx, NULL, &sig_len) != 1) {
        printf("Message digest finalization failed.\n");
        exit (EXIT_FAILURE);
    }
    // allocate signature buffer
    sig = malloc(sizeof(unsigned char) * sig_len);
    if(sig == NULL){
        perror("could not initialize digest buffer");
        exit (EXIT_FAILURE);
    }
    // load signature into buffer
    if (EVP_DigestSignFinal(mdctx, sig, &sig_len) != 1) {
        printf("Message digest finalization failed.\n");
        exit (EXIT_FAILURE);
    }
    fwrite(sig, sig_len, 1, stdout);
    if (ferror(stdout) != 0) {
        fprintf(stdout, "failed to write signature to stdout\n");
        exit (EXIT_FAILURE);
    }
    fflush(stdout);
    // free all allocated resources
    free(sig);
    EVP_MD_CTX_free(mdctx);
    EVP_PKEY_free(key);
    exit (EXIT_SUCCESS);
 }
--- a/Hands-on/src/app/employee.h
+++ b/Hands-on/src/app/employee.h
@ -0,0 +1,23 @@
 #ifndef _APP_INTERMEDIARY_H_
 #define _APP_INTERMEDIARY_H_
 /*
 * @brief getter for employee subcommand syntax string
 *
 * @returns null-terminated syntax string
 */
 char* employee_syntax(void);
 /*
 * @brief CLI implementation for the "employee" subcommand
 *
 * @param argc number of arguments with command and subcommand stripped
 * @param argv arguments with command and subcommand stripped
 *
 * @returns 0 on success, else error with output on stderr
 */
 int handle_employee(int argc, char** argv);
 #endif
--- a/Hands-on/src/app/main.c
+++ b/Hands-on/src/app/main.c
@ -0,0 +1,33 @@
 #include <errno.h>
 #include <string.h>
 #include "embedded_device.h"
 #include "employee.h"
 #include "proxy.h"
 #include "proxysetup.h"
 #include "util.h"
 /*
 * main method of the binary calls the implementation of the specified subcommand
 */
 int main(int argc, char** argv) {
    if(argc < 1)
        syntax_exit();
    set_bin_name(argv[0]);
    if(argc < 2)
        syntax_exit();
    char* command = argv[1];
    if(strcmp(command, "employee")==0)
        handle_employee(argc-2, argv+2);
    else if (strcmp(command, "proxy")==0)
        handle_proxy(argc-2, argv+2);
    else if (strcmp(command, "proxysetup")==0)
        handle_proxysetup(argc-2, argv+2);
    else if (strcmp(command, "embedded")==0)
        handle_embedded_device(argc-2, argv+2);
    else
        syntax_exit();
 }
--- a/Hands-on/src/app/proxy.c
+++ b/Hands-on/src/app/proxy.c
@ -0,0 +1,435 @@
 #include <errno.h>
 #include <sgx_urts.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <openssl/core_names.h>
 #include <openssl/evp.h>
 #include <openssl/param_build.h>
 #include <openssl/pem.h>
 #include <sgx_tcrypto.h>
 #include "enclave_u.h"
 #include "proxy.h"
 #include "util.h"
 struct ProxyArgs {
    char* sealed_key_file_path;
    char* sgx_token_path;
    char* employee_public_key_path;
    char* firmware_path;
 };
 char* proxy_syntax(void) {
    return
        "proxy               implementation of the enclave-powered SignatureProxy\n"
        "                    expects intermediary signature on stdin\n"
        "                    outputs proxied signature on stdout\n"
        "                    WARNING: output is binary format, may mess up terminal\n"
        "    -pkey <path>    file path of the sealed proxy key\n"
        "    -epub <path>    path of the PEM encoded employee public key\n"
        "    -firm <path>    path of the firmware\n"
        "    -token <path>   (optional) file path of the sgx token\n";
 }
 static EVP_PKEY *sgx_public_to_EVP_PKEY(const sgx_ec256_public_t *p_public)
 {
 	EVP_PKEY *evp_key = NULL;
 	EVP_PKEY_CTX *pkey_ctx = NULL;
 	BIGNUM *bn_pub_x = NULL;
 	BIGNUM *bn_pub_y = NULL;
 	EC_POINT *point = NULL;
    EC_GROUP* group = NULL;
 	OSSL_PARAM_BLD *params_build = NULL;
 	OSSL_PARAM *params = NULL;
 	const char *curvename = NULL;
 	int nid = 0;
 	size_t key_len;
 	unsigned char pub_key[SGX_ECP256_KEY_SIZE+4];
    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
 	if (group == NULL)
        return NULL;
 	do {
 		// converts the x value of public key, represented as positive integer in little-endian into a BIGNUM
 		bn_pub_x = BN_lebin2bn((unsigned char*)p_public->gx, sizeof(p_public->gx), bn_pub_x);
 		if (NULL == bn_pub_x) {
 			break;
 		}
 		// converts the y value of public key, represented as positive integer in little-endian into a BIGNUM
 		bn_pub_y = BN_lebin2bn((unsigned char*)p_public->gy, sizeof(p_public->gy), bn_pub_y);
 		if (NULL == bn_pub_y) {
 			break;
 		}
 		// creates new point and assigned the group object that the point relates to
 		point = EC_POINT_new(group);
 		if (NULL == point) {
 			break;
 		}
 		// sets point based on public key's x,y coordinates
 		if (1 != EC_POINT_set_affine_coordinates(group, point, bn_pub_x, bn_pub_y, NULL)) {
 			break;
 		}
 		// check point if the point is on curve
 		if (1 != EC_POINT_is_on_curve(group, point, NULL)) {
 			break;
 		}
 		// convert point to octet string
 		key_len = EC_POINT_point2oct(group, point, POINT_CONVERSION_COMPRESSED, pub_key, sizeof(pub_key), NULL);
 		if (key_len == 0) {
 			break;
 		}
 		// build OSSL_PARAM
 		params_build = OSSL_PARAM_BLD_new();
 		if (NULL == params_build) {
 			break;
 		}
 		nid = EC_GROUP_get_curve_name(group);
 		if (nid == NID_undef) {
 			break;
 		}
 		curvename = OBJ_nid2sn(nid);
 		if (curvename == NULL) {
 			break;
 		}
 		if (1 != OSSL_PARAM_BLD_push_utf8_string(params_build, "group", curvename, 0)) {
 			break;
 		}
 		if (1 != OSSL_PARAM_BLD_push_octet_string(params_build, OSSL_PKEY_PARAM_PUB_KEY, pub_key, key_len)) {
 			break;
 		}
 		params = OSSL_PARAM_BLD_to_param(params_build);
 		if (NULL == params) {
 			break;
 		}
 		// get pkey from params
 		pkey_ctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
 		if (NULL == pkey_ctx) {
 			break;
 		}
 		if (1 != EVP_PKEY_fromdata_init(pkey_ctx)) {
 			break;
 		}
 		if (1 != EVP_PKEY_fromdata(pkey_ctx, &evp_key, EVP_PKEY_PUBLIC_KEY, params)) {
 			EVP_PKEY_free(evp_key);
 			evp_key = NULL;
 		}
 	} while(0);
 	BN_clear_free(bn_pub_x);
 	BN_clear_free(bn_pub_y);
 	EC_POINT_clear_free(point);
 	OSSL_PARAM_free(params);
 	OSSL_PARAM_BLD_free(params_build);
 	EVP_PKEY_CTX_free(pkey_ctx);
    EC_GROUP_free(group);
 	return evp_key;
 }
 static int EVP_PKEY_to_sgx_public(EVP_PKEY* ecdsa_key, sgx_ec256_public_t* sgx_public) {
    EC_GROUP* group = NULL;
 	EC_POINT *point = NULL;
    BIGNUM* pub_x = NULL;
 	BIGNUM* pub_y = NULL;
    size_t ec_key_buf_len = 0;
    unsigned char ec_key_buf[1024];
    int ret;
    int retval;
    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
 	if (group == NULL)
        return 1;
    point = EC_POINT_new(group);
    if (point == NULL)
        return 2;
    ret = EVP_PKEY_get_octet_string_param(ecdsa_key, OSSL_PKEY_PARAM_PUB_KEY, ec_key_buf, 1024, &ec_key_buf_len);
    if (ret != 1)
        return 3;
    ret = EC_POINT_oct2point(group, point, ec_key_buf, ec_key_buf_len, NULL);
    if (ret != 1){
        retval = 4;
        goto cleanup;
    }
    pub_x = BN_new();
    pub_y = BN_new();
    ret = EC_POINT_get_affine_coordinates(group, point, pub_x, pub_y, NULL);
    if (ret != 1){
        retval = 5;
        goto cleanup;
    }
    ret = BN_bn2lebinpad(pub_x, sgx_public->gx, SGX_ECP256_KEY_SIZE);
    if (ret == -1){
        retval = 6;
        goto cleanup;
    }
    ret = BN_bn2lebinpad(pub_y, sgx_public->gy, SGX_ECP256_KEY_SIZE);
    if (ret == -1){
        retval = 7;
        goto cleanup;
    }
    retval = 0;
 cleanup:
    if (pub_x != NULL)
        BN_clear_free(pub_x);
    if (pub_y != NULL)
        BN_clear_free(pub_y);
    if (point != NULL)
        EC_POINT_clear_free(point);
    if (group != NULL)
        EC_GROUP_free(group);
    return (retval);
 }
 static int ECDSA_SIG_to_sgx_signature(ECDSA_SIG* ecdsa_sig, sgx_ec256_signature_t* sgx_signature) {
    const BIGNUM* r = NULL;
 	const BIGNUM* s = NULL;
    int ret;
    r = ECDSA_SIG_get0_r(ecdsa_sig);
    s = ECDSA_SIG_get0_s(ecdsa_sig);
    ret = BN_bn2lebinpad(r, (unsigned char*)sgx_signature->x, SGX_ECP256_KEY_SIZE);
    if (ret == -1)
        return (1);
    ret = BN_bn2lebinpad(s, (unsigned char*)sgx_signature->y, SGX_ECP256_KEY_SIZE);
    if (ret == -1)
        return (2);
    return (0);
 }
 /*
 * This function is a modified version of the `sgx_ecdsa_verify_hash` function in the [Intel SGX crypto library](https://github.com/intel/linux-sgx/blob/main/sdk/tlibcrypto/sgxssl/sgx_ecc256_ecdsa.cpp).
 * The specified License applies.
 */
 static int sgx_signature_to_ECDSA_SIG(sgx_ec256_signature_t* sgx_signature, ECDSA_SIG** ecdsa_signature) {
 	BIGNUM *bn_r = NULL;
 	BIGNUM *bn_s = NULL;
 	// converts the x value of the signature, represented as positive integer in little-endian into a BIGNUM
 	//
 	bn_r = BN_lebin2bn((unsigned char*)sgx_signature->x, sizeof(sgx_signature->x), 0);
 	if (bn_r == NULL)
        return (1);
 	// converts the y value of the signature, represented as positive integer in little-endian into a BIGNUM
 	//
 	bn_s = BN_lebin2bn((unsigned char*)sgx_signature->y, sizeof(sgx_signature->y), 0);
 	if (NULL == bn_s) {
        if (bn_r != NULL)
 		    BN_clear_free(bn_r);
        return (2);
 	}
 	// allocates a new ECDSA_SIG structure (note: this function also allocates the BIGNUMs) and initialize it
 	//
 	*ecdsa_signature = ECDSA_SIG_new();
 	if (NULL == *ecdsa_signature) {
        if (bn_r != NULL)
 		    BN_clear_free(bn_r);
        if (bn_s != NULL)
 		    BN_clear_free(bn_s);
        return (3);
 	}
 	// setes the r and s values of ecdsa_sig
 	// calling this function transfers the memory management of the values to the ECDSA_SIG object,
 	// and therefore the values that have been passed in should not be freed directly after this function has been called
 	//
 	if (1 != ECDSA_SIG_set0(*ecdsa_signature, bn_r, bn_s)) {
 		ECDSA_SIG_free(*ecdsa_signature);
 		*ecdsa_signature = NULL;
        if (bn_r != NULL)
 		    BN_clear_free(bn_r);
        if (bn_s != NULL)
 		    BN_clear_free(bn_s);
        return (4);
 	}
    return (0);
 }
 int handle_proxy(int argc, char** argv) {
    struct ProxyArgs args = {
        NULL,
        NULL,
        NULL
    };
    uint8_t* sealed;
    size_t sealed_len;
    uint8_t* firmware;
    size_t firmware_len;
 	unsigned char* ecdsa_signature_data;
 	size_t ecdsa_signature_size = 0;
    uint8_t signature[70];
    sgx_status_t ret;
    ECDSA_SIG* ecdsa_signature;
    sgx_ec256_signature_t sgx_signature;
    /*
     * Parse Input
     */
    int i = 0;
    while(i < argc) {
        if(strcmp(argv[i], "-pkey")==0 && argc-i >=2){
            args.sealed_key_file_path = argv[i+1];
            i += 2;
        }else if(strcmp(argv[i], "-token")==0 && argc-i >=2){
            args.sgx_token_path = argv[i+1];
            i += 2;
        }else if(strcmp(argv[i], "-epub")==0 && argc-i >=2){
            args.employee_public_key_path = argv[i+1];
            i += 2;
        }else if(strcmp(argv[i], "-firm")==0 && argc-i >=2){
            args.firmware_path = argv[i+1];
            i += 2;
        }else
            syntax_exit();
    }
    if(args.sealed_key_file_path == NULL || args.employee_public_key_path == NULL || args.firmware_path == NULL)
        syntax_exit();
    /*
     * Read And Parse Signature Input
     */
    ecdsa_signature_data = malloc(1024);
    if (ecdsa_signature_data == NULL) {
        perror("failed to allocate signature");
        exit (EXIT_FAILURE);
    }
    ecdsa_signature_size = fread(ecdsa_signature_data, 1, 1024, stdin);
    if (ferror(stdin) != 0) {
        fprintf(stderr, "failed to read signature from stdin\n");
        exit (EXIT_FAILURE);
    }
    ecdsa_signature = ECDSA_SIG_new();
    ecdsa_signature = d2i_ECDSA_SIG(&ecdsa_signature, (const unsigned char**)&ecdsa_signature_data, ecdsa_signature_size);
    ecdsa_signature_data = NULL;
    if (ecdsa_signature == NULL) {
        fprintf(stderr, "failed to read signature\n");
        exit (EXIT_FAILURE);
    }
    if (ECDSA_SIG_to_sgx_signature(ecdsa_signature, &sgx_signature) != 0) {
        fprintf(stderr, "failed to transform signature\n");
        exit (EXIT_FAILURE);
    }
    ECDSA_SIG_free(ecdsa_signature);
    ecdsa_signature = NULL;
    // Initialize SGX Enclave
    if (initialize_enclave(args.sgx_token_path) != 0)
        exit(1);
    /*
     * Read Employee Public Key
     */
    EVP_PKEY* key = NULL;
    FILE* key_file = fopen(args.employee_public_key_path, "rb");
    if(key_file == NULL){
        perror("Error opening employee public key file");
        exit(1);
    }
    key = PEM_read_PUBKEY(key_file, &key, NULL, NULL);
    if(key == NULL) {
        fprintf(stderr, "failed to read employee public key\n");
        exit (EXIT_FAILURE);
    }
    fclose(key_file);
    sgx_ec256_public_t sgx_public;
    if (EVP_PKEY_to_sgx_public(key, &sgx_public) != 0) {
        fprintf(stderr, "failed transform employee public key\n");
        exit (EXIT_FAILURE);
    }
    //Read Sealed Proxy Keypair
    if (load_file(args.sealed_key_file_path, &sealed, &sealed_len)!=0){
        fprintf(stderr, "failed to read sealed key\n");
        exit (EXIT_FAILURE);
    }
    // Read Firmware
    if (load_file(args.firmware_path, &firmware, &firmware_len)!=0){
        fprintf(stderr, "failed to read firmware\n");
        exit (EXIT_FAILURE);
    }
    /*
     * Use Enclave To Resign the Firmware
     */
    sign_firmware(get_global_eid(), &ret, firmware, firmware_len, sealed, sealed_len, (uint8_t*)&sgx_public, (uint8_t*)&sgx_signature);
    if (ret != SGX_SUCCESS) {
        sgx_print_error_message(ret);
        exit (1);
    }
    free(sealed);
    free(firmware);
    /*
     * Output Signature
     */
    if (sgx_signature_to_ECDSA_SIG(&sgx_signature, &ecdsa_signature) != 0) {
        fprintf(stderr, "could not convert signature\n");
        exit (EXIT_FAILURE);
    }
    ecdsa_signature_data = NULL;
 	ecdsa_signature_size = i2d_ECDSA_SIG(ecdsa_signature, &ecdsa_signature_data);
 	if (ecdsa_signature_size <= 0) {
        fprintf(stderr, "could not convert signature\n");
        exit (EXIT_FAILURE);
 	}
    fwrite(ecdsa_signature_data, ecdsa_signature_size, 1, stdout);
    if (ferror(stdout) != 0) {
        fprintf(stderr, "could not write signature to stdout\n");
        exit (EXIT_FAILURE);
    }
    fflush(stdout);
    free(ecdsa_signature_data);
    ECDSA_SIG_free(ecdsa_signature);
    exit (EXIT_SUCCESS);
 }
--- a/Hands-on/src/app/proxy.h
+++ b/Hands-on/src/app/proxy.h
@ -0,0 +1,23 @@
 #ifndef _APP_PROXY_H_
 #define _APP_PROXY_H_
 /*
 * @brief getter for proxy subcommand syntax string
 *
 * @returns null-terminated syntax string
 */
 char* proxy_syntax(void);
 /*
 * @brief CLI implementation for the "proxy" subcommand
 *
 * @param argc number of arguments with command and subcommand stripped
 * @param argv arguments with command and subcommand stripped
 *
 * @returns 0 on success, else error with output on stderr
 */
 int handle_proxy(int argc, char** argv);
 #endif
--- a/Hands-on/src/app/proxysetup.c
+++ b/Hands-on/src/app/proxysetup.c
@ -0,0 +1,237 @@
 #include <errno.h>
 #include <sgx_urts.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <openssl/core_names.h>
 #include <openssl/evp.h>
 #include <openssl/param_build.h>
 #include <openssl/pem.h>
 #include <sgx_tcrypto.h>
 #include "enclave_u.h"
 #include "proxysetup.h"
 #include "util.h"
 struct ProxysetupArgs {
    char* sealed_key_file_path;
    char* sgx_token_path;
 };
 char* proxysetup_syntax(void) {
    return
        "proxysetup          implementation of the enclave-powered SignatureProxy\n"
        "                    outputs public key on stdout\n"
        "    -pkey <path>    file path of the sealed proxy key\n"
        "    -token <path>   (optional) file path of the sgx token\n";
 }
 /*
 * This function is a modified version of the `get_pub_key_from_coords` function in the [Intel SGX crypto library](https://github.com/intel/linux-sgx/blob/c1ceb4fe146e0feb1097dee81c7e89925443e43c/sdk/tlibcrypto/sgxssl/sgx_ecc256.cpp).
 * The specified License applies.
 */
 static EVP_PKEY *sgx_public_to_EVP_PKEY(const sgx_ec256_public_t *p_public)
 {
 	EVP_PKEY *evp_key = NULL;
 	EVP_PKEY_CTX *pkey_ctx = NULL;
 	BIGNUM *bn_pub_x = NULL;
 	BIGNUM *bn_pub_y = NULL;
 	EC_POINT *point = NULL;
    EC_GROUP* group = NULL;
 	OSSL_PARAM_BLD *params_build = NULL;
 	OSSL_PARAM *params = NULL;
 	const char *curvename = NULL;
 	int nid = 0;
 	size_t key_len;
 	unsigned char pub_key[SGX_ECP256_KEY_SIZE+4];
    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
 	if (group == NULL)
        return NULL;
 	do {
 		// converts the x value of public key, represented as positive integer in little-endian into a BIGNUM
 		bn_pub_x = BN_lebin2bn((unsigned char*)p_public->gx, sizeof(p_public->gx), bn_pub_x);
 		if (NULL == bn_pub_x) {
 			break;
 		}
 		// converts the y value of public key, represented as positive integer in little-endian into a BIGNUM
 		bn_pub_y = BN_lebin2bn((unsigned char*)p_public->gy, sizeof(p_public->gy), bn_pub_y);
 		if (NULL == bn_pub_y) {
 			break;
 		}
 		// creates new point and assigned the group object that the point relates to
 		point = EC_POINT_new(group);
 		if (NULL == point) {
 			break;
 		}
 		// sets point based on public key's x,y coordinates
 		if (1 != EC_POINT_set_affine_coordinates(group, point, bn_pub_x, bn_pub_y, NULL)) {
 			break;
 		}
 		// check point if the point is on curve
 		if (1 != EC_POINT_is_on_curve(group, point, NULL)) {
 			break;
 		}
 		// convert point to octet string
 		key_len = EC_POINT_point2oct(group, point, POINT_CONVERSION_COMPRESSED, pub_key, sizeof(pub_key), NULL);
 		if (key_len == 0) {
 			break;
 		}
 		// build OSSL_PARAM
 		params_build = OSSL_PARAM_BLD_new();
 		if (NULL == params_build) {
 			break;
 		}
 		nid = EC_GROUP_get_curve_name(group);
 		if (nid == NID_undef) {
 			break;
 		}
 		curvename = OBJ_nid2sn(nid);
 		if (curvename == NULL) {
 			break;
 		}
 		if (1 != OSSL_PARAM_BLD_push_utf8_string(params_build, "group", curvename, 0)) {
 			break;
 		}
 		if (1 != OSSL_PARAM_BLD_push_octet_string(params_build, OSSL_PKEY_PARAM_PUB_KEY, pub_key, key_len)) {
 			break;
 		}
 		params = OSSL_PARAM_BLD_to_param(params_build);
 		if (NULL == params) {
 			break;
 		}
 		// get pkey from params
 		pkey_ctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
 		if (NULL == pkey_ctx) {
 			break;
 		}
 		if (1 != EVP_PKEY_fromdata_init(pkey_ctx)) {
 			break;
 		}
 		if (1 != EVP_PKEY_fromdata(pkey_ctx, &evp_key, EVP_PKEY_PUBLIC_KEY, params)) {
 			EVP_PKEY_free(evp_key);
 			evp_key = NULL;
 		}
 	} while(0);
 	BN_clear_free(bn_pub_x);
 	BN_clear_free(bn_pub_y);
 	EC_POINT_clear_free(point);
 	OSSL_PARAM_free(params);
 	OSSL_PARAM_BLD_free(params_build);
 	EVP_PKEY_CTX_free(pkey_ctx);
    EC_GROUP_free(group);
 	return evp_key;
 }
 int handle_proxysetup(int argc, char** argv) {
    struct ProxysetupArgs args = {
        NULL,
        NULL
    };
    FILE* sealed_file;
    int sealed_size;
    uint8_t* sealed;
    sgx_ec256_public_t sgx_public_key;
    EVP_PKEY* public_key;
    sgx_status_t sgx_ret;
    /*
     * Parse Input
     */
    int i = 0;
    while(i < argc) {
        if(strcmp(argv[i], "-pkey")==0 && argc-i >=2){
            args.sealed_key_file_path = argv[i+1];
            i += 2;
        }else if(strcmp(argv[i], "-token")==0 && argc-i >=2){
            args.sgx_token_path = argv[i+1];
            i += 2;
        }else
            syntax_exit();
    }
    if(args.sealed_key_file_path == NULL)
        syntax_exit();
    /*
     * Initialize SGX Enclave
     */
    if (initialize_enclave(args.sgx_token_path) != 0)
        exit (EXIT_FAILURE);
    /*
     * Setup Sealed Keypair
     */
    sealed_file = fopen(args.sealed_key_file_path, "wb");
    if(sealed_file == NULL){
        perror("Error opening sealed_key_file file");
        exit (EXIT_FAILURE);
    }
    sgx_ret = get_sealed_size(get_global_eid(), &sealed_size);
    if (sgx_ret != SGX_SUCCESS) {
        sgx_print_error_message(sgx_ret);
        exit (EXIT_FAILURE);
    }
    sealed = malloc(sizeof(uint8_t)*sealed_size);
    if (sealed == NULL) {
        fprintf(stderr, "failed to allocate for sealed key");
        exit (EXIT_FAILURE);
    }
    /*
     * Use Enclave To Generate Keypair
     */
    generate_key_pair(get_global_eid(), &sgx_ret, sealed, sealed_size);
    if (sgx_ret != SGX_SUCCESS) {
        sgx_print_error_message(sgx_ret);
        exit (EXIT_FAILURE);
    }
    /*
     * Store Sealed Keypair
     */
    if (fwrite(sealed, sealed_size, 1, sealed_file) != 1 || ferror(sealed_file) != 0) {
        fprintf(stderr, "failed to write sealed key");
        exit (EXIT_FAILURE);
    }
    fflush(sealed_file);
    fclose(sealed_file);
    /*
     * Fetch Public Key From Enclave And Print
     */
    get_public_key(get_global_eid(), &sgx_ret, sealed, sealed_size, (uint8_t*)&sgx_public_key);
    if (sgx_ret != SGX_SUCCESS) {
        sgx_print_error_message(sgx_ret);
        exit (EXIT_FAILURE);
    }
    public_key = sgx_public_to_EVP_PKEY(&sgx_public_key);
    if (PEM_write_PUBKEY(stdout, public_key) != 1) {
        fprintf(stderr, "could not write publickey\n");
        exit (EXIT_FAILURE);
    }
    fflush(stdout);
    EVP_PKEY_free(public_key);
    free(sealed);
    exit (EXIT_SUCCESS);
 }
--- a/Hands-on/src/app/proxysetup.h
+++ b/Hands-on/src/app/proxysetup.h
@ -0,0 +1,23 @@
 #ifndef _APP_PROXYSETUP_H_
 #define _APP_PROXYSETUP_H_
 /*
 * @brief getter for proxysetup subcommand syntax string
 *
 * @returns null-terminated syntax string
 */
 char* proxysetup_syntax(void);
 /*
 * @brief CLI implementation for the "proxysetup" subcommand
 *
 * @param argc number of arguments with command and subcommand stripped
 * @param argv arguments with command and subcommand stripped
 *
 * @returns 0 on success, else error with output on stderr
 */
 int handle_proxysetup(int argc, char** argv);
 #endif
--- a/Hands-on/src/app/util.c
+++ b/Hands-on/src/app/util.c
@ -0,0 +1,247 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include "embedded_device.h"
 #include "employee.h"
 #include "util.h"
 #include "proxy.h"
 #include "proxysetup.h"
 static char* BIN_NAME = "SignatureProxy";
 static sgx_enclave_id_t global_eid = 0;
 void syntax_exit(void) {
    char* syntax =
        "SignatureProxy Version 0.0.0\n"
        "Syntax: %s <command> <arguments>\n"
        "\n"
        "Commands:\n"
        "%s"
        "\n"
        "%s"
        "\n"
        "%s"
        "\n"
        "%s";
    printf(syntax, BIN_NAME, proxysetup_syntax(), employee_syntax(), proxy_syntax(), embedded_device_syntax());
    exit (EXIT_FAILURE);
 }
 void set_bin_name(char* bin_name) {
    BIN_NAME = bin_name;
 }
 /*
 * This definition is copied from the provided SGX Examples.
 * The specified License applies.
 */
 typedef struct _sgx_errlist_t {
    sgx_status_t err;
    const char *msg;
    const char *sug; /* Suggestion */
 } sgx_errlist_t;
 /*
 * This definition is copied from the provided SGX Examples.
 * The specified License applies.
 */
 /* Error code returned by sgx_create_enclave */
 static sgx_errlist_t sgx_errlist[] = {
    {
        SGX_ERROR_UNEXPECTED,
        "Unexpected error occurred.",
        NULL
    },
    {
        SGX_ERROR_INVALID_PARAMETER,
        "Invalid parameter.",
        NULL
    },
    {
        SGX_ERROR_OUT_OF_MEMORY,
        "Out of memory.",
        NULL
    },
    {
        SGX_ERROR_ENCLAVE_LOST,
        "Power transition occurred.",
        "Please refer to the sample \"PowerTransition\" for details."
    },
    {
        SGX_ERROR_INVALID_ENCLAVE,
        "Invalid enclave image.",
        NULL
    },
    {
        SGX_ERROR_INVALID_ENCLAVE_ID,
        "Invalid enclave identification.",
        NULL
    },
    {
        SGX_ERROR_INVALID_SIGNATURE,
        "Invalid enclave signature.",
        NULL
    },
    {
        SGX_ERROR_OUT_OF_EPC,
        "Out of EPC memory.",
        NULL
    },
    {
        SGX_ERROR_NO_DEVICE,
        "Invalid SGX device.",
        "Please make sure SGX module is enabled in the BIOS, and install SGX driver afterwards."
    },
    {
        SGX_ERROR_MEMORY_MAP_CONFLICT,
        "Memory map conflicted.",
        NULL
    },
    {
        SGX_ERROR_INVALID_METADATA,
        "Invalid enclave metadata.",
        NULL
    },
    {
        SGX_ERROR_DEVICE_BUSY,
        "SGX device was busy.",
        NULL
    },
    {
        SGX_ERROR_INVALID_VERSION,
        "Enclave version was invalid.",
        NULL
    },
    {
        SGX_ERROR_INVALID_ATTRIBUTE,
        "Enclave was not authorized.",
        NULL
    },
    {
        SGX_ERROR_ENCLAVE_FILE_ACCESS,
        "Can't open enclave file.",
        NULL
    },
 };
 /*
 * This Method is copied from the provided SGX Examples.
 * The specified License applies.
 */
 /* Check error conditions for loading enclave */
 void sgx_print_error_message(sgx_status_t ret)
 {
    size_t idx = 0;
    size_t ttl = sizeof sgx_errlist/sizeof sgx_errlist[0];
    for (idx = 0; idx < ttl; idx++) {
        if(ret == sgx_errlist[idx].err) {
            if(NULL != sgx_errlist[idx].sug)
                printf("Info: %s\n", sgx_errlist[idx].sug);
            printf("Error: %s\n", sgx_errlist[idx].msg);
            break;
        }
    }
    if (idx == ttl)
    	printf("Error code is 0x%X. Please refer to the \"Intel SGX SDK Developer Reference\" for more details.\n", ret);
 }
 /*
 * This Method is copied from the provided SGX Examples.
 * The specified License applies.
 */
 int initialize_enclave(char* token_path) {
    FILE* sgx_token_file = NULL;
    sgx_launch_token_t token = {0};
    sgx_status_t ret;
    int updated = 0;
    if (token_path != NULL) {
        sgx_token_file = fopen(token_path, "rb");
    }
    if(sgx_token_file == NULL){
        if (errno != ENOENT && token_path != NULL) {
            perror("Error opening sgx token file");
            exit(1);
        }
    }else{
        size_t read_num = fread(token, 1, sizeof(sgx_launch_token_t), sgx_token_file);
        if (read_num != 0 && read_num != sizeof(sgx_launch_token_t)) {
            fprintf(stderr, "sgx token file is corrupted");
            return (1);
        }
    }
    ret = sgx_create_enclave("enclave.signed.so", SGX_DEBUG_FLAG, &token, &updated, &global_eid, NULL);
    if (ret != SGX_SUCCESS) {
        sgx_print_error_message(ret);
        return (1);
    }
    if (updated && token_path != NULL) {
        sgx_token_file = freopen(token_path, "wb", sgx_token_file);
        if(sgx_token_file == NULL){
            perror("Error opening sgx token file");
            return (1);
        }
        size_t write_num = fwrite(token, 1, sizeof(sgx_launch_token_t), sgx_token_file);
        if (write_num != sizeof(sgx_launch_token_t)){
            fprintf(stderr,"Warning: Failed to save launch token to \"%s\".\n", token_path);
            return (1);
        }
    }
    return (0);
 }
 sgx_enclave_id_t get_global_eid(void){
    return global_eid;
 }
 int load_file(const char* path, uint8_t** data, size_t* data_len) {
    FILE* file;
    size_t file_size;
    uint8_t* buf;
    int file_des = open(path, O_RDWR);
    if(file_des == 0)
        return (1);
    struct stat stat;
    if (fstat(file_des, &stat) != 0){
        close(file_des);
        return (2);
    }
    close(file_des);
    file_size = stat.st_size;
    buf = malloc(file_size);
    if (buf == NULL)
        return (3);
    file = fopen(path, "rb");
    if(file == NULL){
        free(buf);
        return (4);
    }
    if (fread(buf, file_size, 1, file) != 1 || ferror(file) != 0) {
        free(buf);
        fclose(file);
        return (5);
    }
    fclose(file);
    *data = buf;
    *data_len = file_size;
    return (0);
 }
--- a/Hands-on/src/app/util.h
+++ b/Hands-on/src/app/util.h
@ -0,0 +1,33 @@
 #ifndef _APP_UTIL_H_
 #define _APP_UTIL_H_
 #include <sgx_urts.h>
 /*
 * @brief prints the command syntax and exits with EXIT_FAILURE
 */
 void syntax_exit(void);
 void set_bin_name(char* bin_name);
 void sgx_print_error_message(sgx_status_t ret);
 int initialize_enclave(char* token_path);
 sgx_enclave_id_t get_global_eid(void);
 /*
 * @brief loads a file completely into the HEAP
 *
 * Loads a File into HEAP and returns a dynamically allocated buffer.
 *
 * @param path      path of the file
 * @param data      allocated buffer output
 * @param data_len  length of the allocated buffer
 * @returns 0 on success, non zero on error
 */
 int load_file(const char* path, uint8_t** data, size_t* data_len);
 #endif
--- a/Hands-on/src/enclave/enclave.c
+++ b/Hands-on/src/enclave/enclave.c
@ -0,0 +1,343 @@
 /*
 * Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
 #include <stdarg.h>
 #include <stdio.h>      /* vsnprintf */
 #include <string.h>
 #include <stdlib.h>
 #include "enclave.h"
 #include "enclave_t.h"
 #include <sgx_tseal.h>
 #include <sgx_error.h>
 #include <sgx_tcrypto.h>
 #ifndef SK_SIZE
 #define SK_SIZE SGX_ECP256_KEY_SIZE
 #endif
 #ifndef PK_SIZE
 #define PK_SIZE 2*SK_SIZE
 #endif
 #ifndef DG_SIZE
 #define DG_SIZE SK_SIZE
 #endif
 #ifndef SI_SIZE
 #define SI_SIZE 2*SK_SIZE
 #endif
 /*
 *   Bobs and Alices public keys
 */
 const sgx_ec256_public_t authorized[2] = {
    {
        .gx = { 
            0x9c, 0x72, 0x2b, 0x52, 0x0e, 0xff, 0x07, 0xdc,
            0x7a, 0x32, 0x19, 0xbb, 0xd8, 0x41, 0x94, 0x2c,
            0xee, 0x17, 0xb2, 0xf6, 0x2e, 0x08, 0x61, 0xab,
            0xbc, 0x50, 0xaf, 0xb6, 0x2e, 0xf9, 0x2c, 0xee
        },
        .gy = {
            0x8c, 0x84, 0x2f, 0xb5, 0x94, 0xca, 0x60, 0x94,
            0xb0, 0xdc, 0x8a, 0xcf, 0x17, 0x91, 0xd3, 0xab,
            0x29, 0x0e, 0x81, 0x8c, 0xf6, 0x95, 0xc6, 0x92,
            0x87, 0x0e, 0x1d, 0x76, 0x56, 0xba, 0x51, 0xbb 
        }
    },
    {
        .gx = {
            0x8d, 0x96, 0xa3, 0x4f, 0x1a, 0x18, 0x10, 0x00,
            0x72, 0xb5, 0x42, 0x4f, 0x1c, 0xfb, 0xb6, 0xd0,
            0x29, 0x4f, 0x5f, 0xd2, 0xef, 0x29, 0x49, 0x1c,
            0xea, 0x2b, 0xf5, 0x61, 0x5e, 0x50, 0xe5, 0x76
        },
        .gy = {
            0xb2, 0x58, 0xa6, 0xf9, 0xf3, 0xc4, 0xb5, 0xdf,
            0xa0, 0x4b, 0xb6, 0xad, 0xdd, 0xb1, 0x04, 0xec,
            0x93, 0x2e, 0x2f, 0xce, 0x34, 0x71, 0x7d, 0xf4,
            0x9d, 0xa4, 0xa5, 0xf1, 0x47, 0x0a, 0xba, 0xa1
        }
    }
 };
 int get_digest_size() {
    return DG_SIZE;
 }
 int get_sealed_size() {
    return sgx_calc_sealed_data_size(PK_SIZE, SK_SIZE);
 }
 int get_signature_size() {
    return SI_SIZE;
 }
 int get_public_key_size() {
    return PK_SIZE;
 }
 int get_private_key_size() {
    return SK_SIZE;
 }
 /*
 * seals a key pair
 */
 static sgx_status_t seal_key_pair(const sgx_ec256_private_t *private, const sgx_ec256_public_t *public, uint8_t **sealed) {
    // allocate temporary buffers on stack
    uint8_t pk[PK_SIZE] = {0};
    uint8_t sk[SK_SIZE] = {0};
    // copy key pair into buffers
    memcpy(pk, public->gx, PK_SIZE);
    memcpy(sk, private->r, SK_SIZE);
    // seal keypair
    return sgx_seal_data(PK_SIZE, (const uint8_t *)pk, SK_SIZE, (const uint8_t *)sk, get_sealed_size(), (sgx_sealed_data_t *) *sealed);
 }
 /*
 * unseals a key pair
 */
 static sgx_status_t unseal_key_pair(const uint8_t *sealed, sgx_ec256_private_t *private, sgx_ec256_public_t *public) {
    // invalid parameter handling
    if(sealed == NULL) {
        return SGX_ERROR_INVALID_PARAMETER;
    }
    // allocate temporary buffers on stack
    uint8_t pk[PK_SIZE] = {0};
    uint8_t sk[SK_SIZE] = {0};
    // calculate public_key size and return error for unexpected results
    uint32_t pk_size = sgx_get_add_mac_txt_len((const sgx_sealed_data_t *)sealed);
    uint32_t sk_size = sgx_get_encrypt_txt_len((const sgx_sealed_data_t *)sealed);
    if ((pk_size != PK_SIZE) || (sk_size != SK_SIZE)) {
        return SGX_ERROR_UNEXPECTED;
    }
    // unseal ecc key pair
    sgx_status_t status = sgx_unseal_data((const sgx_sealed_data_t *)sealed, pk, &pk_size, sk, &sk_size);
    if (status != SGX_SUCCESS) {
        return status;
    }
    // copy buffers into key structs
    if(public != NULL) {
        memcpy(public->gx, pk, PK_SIZE);
    }
    if (private != NULL) {
        memcpy(private->r, sk, SK_SIZE);
    }
    // return success
    return status;
 }
 sgx_status_t generate_key_pair(uint8_t *sealed, uint32_t sealed_size) {
    // invalid parameter handling
    if((sealed == NULL) || (sealed_size != get_sealed_size())) {
        return SGX_ERROR_INVALID_PARAMETER;   
    }
    // declare needed structs
    sgx_ecc_state_handle_t ecc_handle;
    sgx_ec256_private_t private;
    sgx_ec256_public_t public;
    sgx_status_t status;
    // open ecc handle
    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
        return status;
    }
    // create ecc key pair
    if((status = sgx_ecc256_create_key_pair(&private, &public, ecc_handle)) != SGX_SUCCESS) {
        goto exit;
    }
    // seal key pair
    status = seal_key_pair(&private, &public, &sealed);
    exit: ;
    sgx_ecc256_close_context(ecc_handle);
    return status;
 }
 sgx_status_t get_public_key(const uint8_t *sealed, uint32_t sealed_size, uint8_t *public) {
    // invalid parameter handling
    if((sealed == NULL) || (sealed_size != get_sealed_size())) {
        return SGX_ERROR_INVALID_PARAMETER;
    } else if(public == NULL) {
        return SGX_ERROR_INVALID_PARAMETER;
    }
    // unseal public key
    sgx_status_t status;
    if((status = unseal_key_pair(sealed, NULL, (sgx_ec256_public_t *)public)) != SGX_SUCCESS) {
        return status;
    }
    // return success
    return status;
 }
 /*
 * verifies an ecdsa signature
 */
 static sgx_status_t verify_signature(const uint8_t *firmware, uint32_t firmware_size, const sgx_ec256_public_t *public, const sgx_ec256_signature_t* ecc_signature) {
    // invalid parameter handling
    if((firmware == NULL) || (firmware_size == 0) || (public == NULL) || (ecc_signature == NULL)) {
        return SGX_ERROR_INVALID_PARAMETER;
    }
    // declare needed structure
    sgx_ecc_state_handle_t ecc_handle;
    // open ecc handle
    sgx_status_t status;
    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
        return status;
    }
    // verify signature
    uint8_t result;
    sgx_status_t verification_status = sgx_ecdsa_verify(firmware, firmware_size, public, ecc_signature, &result, ecc_handle);
    // handle failed verification process
    if(verification_status != SGX_SUCCESS) {
        result = verification_status;
    }
    // close context and return valid signature
    sgx_ecc256_close_context(ecc_handle);
    return result;
 }
 sgx_status_t sign_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, uint8_t *public_key, uint8_t *signature) {
    // invalid parameter handling
    if((firmware == NULL) || (firmware_size == 0)) {
        return SGX_ERROR_INVALID_PARAMETER;
    } else if((public_key == NULL) || (signature == NULL)) {
        return SGX_ERROR_INVALID_PARAMETER;
    } else if((sealed == NULL) || (sealed_size != get_sealed_size())) {
        return SGX_ERROR_INVALID_PARAMETER;
    }
    // verify public key
    for(size_t i = 0; i < sizeof(authorized)/sizeof(authorized[0]); i++) {
        if(memcmp(public_key, authorized[i].gx, PK_SIZE) == 0) {
            goto sign;
        }
    }
    return SGX_ERROR_UNEXPECTED;
    sign: ;
    // declare need structures
    sgx_ec256_signature_t ecc_signature;
    sgx_ecc_state_handle_t ecc_handle;
    sgx_ec256_private_t private;
    // open ecc handle
    sgx_status_t status;
    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
        return status;
    }
    // verify request
    if((status = verify_signature(firmware, firmware_size, (const sgx_ec256_public_t *)public_key, (const sgx_ec256_signature_t *)signature)) != SGX_EC_VALID) {
        goto exit;
    }
    // try unseal keypair
    if(status = unseal_key_pair(sealed, &private, (sgx_ec256_public_t *)public_key) != SGX_SUCCESS) {
        goto exit;
    }
    // create signature
    if((status = sgx_ecdsa_sign(firmware, firmware_size, &private, &ecc_signature, ecc_handle)) != SGX_SUCCESS) {
        goto exit;
    }
    // copy signature to return buffer
    memcpy(signature, ecc_signature.x, SI_SIZE);
    // close ecc handle and return success
    exit: ;
    sgx_ecc256_close_context(ecc_handle);
    return status;
 }
 sgx_status_t verify_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, const uint8_t *public_key, const uint8_t *signature) {
    // invalid parameter handling
    if((firmware == NULL) || (firmware_size == 0) || (signature == NULL)) {
        return SGX_ERROR_INVALID_PARAMETER;
    } else if((sealed == NULL) && (public_key == NULL)) {
        return SGX_ERROR_INVALID_PARAMETER;
    } else if((sealed != NULL) && (public_key != NULL)) {
        return SGX_ERROR_INVALID_PARAMETER;
    } else if((sealed_size != get_sealed_size()) && (public_key == NULL)) {
        return SGX_ERROR_INVALID_PARAMETER;;
    }
    // declare needed structures
    sgx_ec256_public_t public;
    sgx_status_t status;
    // verify signature from staff or enclave
    if(public_key != NULL) {
        // verification only with authorized public keys
        for(size_t i = 0; i < sizeof(authorized)/sizeof(authorized[0]); i++) {
            if(memcmp(public_key, authorized[i].gx, PK_SIZE) == 0) {
                goto verify;
            }
        }   
        return SGX_ERROR_UNEXPECTED;
        verify: ;
        // copy public key into struct
        memcpy(public.gx, public_key, PK_SIZE);
    } else {
        // unseal public key
        if((status = unseal_key_pair(sealed, NULL, &public)) != SGX_SUCCESS) {
            return status;
        }
    }
    // verify signature and return result
    return verify_signature(firmware, firmware_size, &public, (const sgx_ec256_signature_t *)signature);
 }
--- a/Hands-on/src/enclave/enclave.config.xml
+++ b/Hands-on/src/enclave/enclave.config.xml
@ -0,0 +1,12 @@
 <EnclaveConfiguration>
  <ProdID>0</ProdID>
  <ISVSVN>0</ISVSVN>
  <StackMaxSize>0x400000</StackMaxSize>
  <HeapMaxSize>0x1000000</HeapMaxSize>
  <TCSNum>10</TCSNum>
  <TCSPolicy>1</TCSPolicy>
  <!-- Recommend changing 'DisableDebug' to 1 to make the enclave undebuggable for enclave release -->
  <DisableDebug>0</DisableDebug>
  <MiscSelect>0</MiscSelect>
  <MiscMask>0xFFFFFFFF</MiscMask>
 </EnclaveConfiguration>
--- a/Hands-on/src/enclave/enclave.edl
+++ b/Hands-on/src/enclave/enclave.edl
@ -0,0 +1,62 @@
 /*
 * Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
 /* Enclave.edl - Top EDL file. */
 enclave {
    /* Import ECALL/OCALL from sub-directory EDLs.
     *  [from]: specifies the location of EDL file. 
     *  [import]: specifies the functions to import, 
     *  [*]: implies to import all functions.
     */
    trusted {
        public int get_sealed_size();
        public int get_digest_size();
        public int get_signature_size();
        public int get_public_key_size();
        public int get_private_key_size();
        public sgx_status_t generate_key_pair([out, size=sealed_size]uint8_t *sealed, uint32_t sealed_size);
        public sgx_status_t get_public_key([in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [out, size=64]uint8_t *public_key);
        public sgx_status_t sign_firmware([in, size=firmware_size]const uint8_t *firmware, uint32_t firmware_size, [in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [in, out, size=64]uint8_t *public_key, [in, out, size=64]uint8_t *signature);
        public sgx_status_t verify_firmware([in, size=firmware_size]const uint8_t *firmware, uint32_t firmware_size, [in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [in, size=64]const uint8_t *public_key, [in, size=64]const uint8_t *signature);
    };
    /* 
     * ocall_print_string - invokes OCALL to display string buffer inside the enclave.
     *  [in]: copy the string buffer to App outside.
     *  [string]: specifies 'str' is a NULL terminated buffer.
     */
    untrusted {
    };
 };
--- a/Hands-on/src/enclave/enclave.h
+++ b/Hands-on/src/enclave/enclave.h
@ -0,0 +1,113 @@
 /*
 * Copyright (C) 2011-2018 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
 #ifndef _ENCLAVE_H_
 #define _ENCLAVE_H_
 #include <stdint.h>
 #include <sgx_error.h>
 /*
 * returns the size of the sealed key pair
 */
 int get_sealed_size();
 /*
 * returns the length of the hash used in the signature
 */
 int get_digest_size();
 /*
 * returns the size of the signature created by the enclave
 */
 int get_signature_size();
 /*
 * returns the size of the public key
 */
 int get_public_key_size();
 /*
 * returns the size of the private key
 */
 int get_private_key_size();
 /*
 * @brief generates a secp256r1 key pair and returns it sealed by the TEE
 *
 * @param sealed buffer to hold the sealed key pair
 * @param sealed_size size of the sealed key pair
 *
 * @returns SGX_SUCCESS on success, else sgx error code
 */
 sgx_status_t generate_key_pair(uint8_t *sealed, uint32_t sealed_size);
 /*
 * @brief returns the public key of the sealed key pair provided to the enclave
 *
 * @param sealed buffer containing the sealed key pair
 * @param sealed_size size of the sealed key pair
 * @param public_key buffer to hold the public key
 *
 * @returns SGX_SUCCESS on success, SGX_ERROR_INVALID_PARAMETER for invalid parameters, else sgx error code
 */
 sgx_status_t get_public_key(const uint8_t *sealed, const uint32_t sealed_size, uint8_t *public_key);
 /*
 * @brief signs the firmware provided by an authorized employee
 *
 * @param firmware buffer containing the firmware
 * @param firmware_size size of the sealed key pair
 * @param sealed buffer containing the sealed key pair
 * @param sealed_size size of the sealed key pair
 * @param public_key buffer with the employees public key; holds enclaves public key after successful signing
 * @param signature buffer with the employees signature; holds the enclaves signature after successful signing
 *
 * @returns SGX_SUCCESS on success, SGX_ERROR_INVALID_PARAMETER for invalid parameters, else sgx error code
 */
 sgx_status_t sign_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, uint8_t *public_key, uint8_t *signature);
 /*
 * @brief verifies a firmware signature provided by an authorized employee or enclave
 *
 * @param firmware buffer containing the firmware
 * @param firmware_size size of the sealed key pair or NULL
 * @param sealed buffer containing the sealed key pair
 * @param sealed_size size of the sealed key pair
 * @param public_key buffer with the employees public key or NULL
 * @param signature buffer with the employees signature
 *
 * @returns SGX_EC_VALID on success, SGX_EC_INVALID for invalid signatures, SGX_ERROR_INVALID_PARAMETER for invalid parameters, else sgx error code
 */
 sgx_status_t verify_firmware(const uint8_t *firmware, uint32_t firmware_size, const uint8_t *sealed, uint32_t sealed_size, const uint8_t *public_key, const uint8_t *signature);
 #endif /* !_ENCLAVE_H_ */
--- a/Hands-on/src/enclave/enclave.lds
+++ b/Hands-on/src/enclave/enclave.lds
@ -0,0 +1,10 @@
 enclave.so
 {
    global:
        g_global_data_sim;
        g_global_data;
        enclave_entry;
        g_peak_heap_used;
    local:
        *;
 };
--- a/Hands-on/src/enclave/enclave_private.pem
+++ b/Hands-on/src/enclave/enclave_private.pem
@ -0,0 +1,39 @@
 -----BEGIN RSA PRIVATE KEY-----
 MIIG4gIBAAKCAYEAroOogvsj/fZDZY8XFdkl6dJmky0lRvnWMmpeH41Bla6U1qLZ
 AmZuyIF+mQC/cgojIsrBMzBxb1kKqzATF4+XwPwgKz7fmiddmHyYz2WDJfAjIveJ
 ZjdMjM4+EytGlkkJ52T8V8ds0/L2qKexJ+NBLxkeQLfV8n1mIk7zX7jguwbCG1Pr
 nEMdJ3Sew20vnje+RsngAzdPChoJpVsWi/K7cettX/tbnre1DL02GXc5qJoQYk7b
 3zkmhz31TgFrd9VVtmUGyFXAysuSAb3EN+5VnHGr0xKkeg8utErea2FNtNIgua8H
 ONfm9Eiyaav1SVKzPHlyqLtcdxH3I8Wg7yqMsaprZ1n5A1v/levxnL8+It02KseD
 5HqV4rf/cImSlCt3lpRg8U5E1pyFQ2IVEC/XTDMiI3c+AR+w2jSRB3Bwn9zJtFlW
 KHG3m1xGI4ck+Lci1JvWWLXQagQSPtZTsubxTQNx1gsgZhgv1JHVZMdbVlAbbRMC
 1nSuJNl7KPAS/VfzAgEDAoIBgHRXxaynbVP5gkO0ug6Qw/E27wzIw4SmjsxG6Wpe
 K7kfDeRskKxESdsA/xCrKkwGwhcx1iIgS5+Qscd1Yg+1D9X9asd/P7waPmWoZd+Z
 AhlKwhdPsO7PiF3e1AzHhGQwsUTt/Y/aSI1MpHBvy2/s1h9mFCslOUxTmWw0oj/Q
 ldIEgWeNR72CE2+jFIJIyml6ftnb6qzPiga8Bm48ubKh0kvySOqnkmnPzgh+JBD6
 JnBmtZbfPT97bwTT+N6rnPqOOApvfHPf15kWI8yDbprG1l4OCUaIUH1AszxLd826
 5IPM+8gINLRDP1MA6azECPjTyHXhtnSIBZCyWSVkc05vYmNXYUNiXWMajcxW9M02
 wKzFELO8NCEAkaTPxwo4SCyIjUxiK1LbQ9h8PSy4c1+gGP4LAMR8xqP4QKg6zdu9
 osUGG/xRe/uufgTBFkcjqBHtK5L5VI0jeNIUAgW/6iNbYXjBMJ0GfauLs+g1VsOm
 WfdgXzsb9DYdMa0OXXHypmV4GwKBwQDUwQj8RKJ6c8cT4vcWCoJvJF00+RFL+P3i
 Gx2DLERxRrDa8AVGfqaCjsR+3vLgG8V/py+z+dxZYSqeB80Qeo6PDITcRKoeAYh9
 xlT3LJOS+k1cJcEmlbbO2IjLkTmzSwa80fWexKu8/Xv6vv15gpqYl1ngYoqJM3pd
 vzmTIOi7MKSZ0WmEQavrZj8zK4endE3v0eAEeQ55j1GImbypSf7Idh7wOXtjZ7WD
 Dg6yWDrri+AP/L3gClMj8wsAxMV4ZR8CgcEA0fzDHkFa6raVOxWnObmRoDhAtE0a
 cjUj976NM5yyfdf2MrKy4/RhdTiPZ6b08/lBC/+xRfV3xKVGzacm6QjqjZrUpgHC
 0LKiZaMtccCJjLtPwQd0jGQEnKfMFaPsnhOc5y8qVkCzVOSthY5qhz0XNotHHFmJ
 gffVgB0iqrMTvSL7IA2yqqpOqNRlhaYhNl8TiFP3gIeMtVa9rZy31JPgT2uJ+kfo
 gV7sdTPEjPWZd7OshGxWpT6QfVDj/T9T7L6tAoHBAI3WBf2DFvxNL2KXT2QHAZ9t
 k3imC4f7U+wSE6zILaDZyzygA4RUbwG0gv8/TJVn2P/Eynf76DuWHGlaiLWnCbSz
 Az2DHBQBBaku409zDQym3j1ugMRjzzSQWzJg0SIyBH3hTmnYcn3+Uqcp/lEBvGW6
 O+rsXFt3pukqJmIV8HzLGGaLm62BHUeZf3dyWm+i3p/hQAL7Xvu04QW70xuGqdr5
 afV7p5eaeQIJXyGQJ0eylV/90+qxjMKiB1XYg6WYvwKBwQCL/ddpgOdHJGN8uRom
 e7Zq0Csi3hGheMKlKbN3vcxT5U7MdyHtTZZOJbTvxKNNUNYH/8uD+PqDGNneb29G
 BfGzvI3EASyLIcGZF3OhKwZd0jUrWk2y7Vhob91jwp2+t73vdMbkKyI4mHOuXvGv
 fg95si9oO7EBT+Oqvhccd2J+F1IVXncccYnF4u5ZGWt5lLewN/pVr7MjjykeaHqN
 t+rfnQam2psA6fL4zS2zTmZPzR2tnY8Y1GBTi0Ko1OKd1HMCgcAb5cB/7/AQlhP9
 yQa04PLH9ygQkKKptZp7dy5WcWRx0K/hAHRoi2aw1wZqfm7VBNu2SLcs90kCCCxp
 6C5sfJi6b8NpNbIPC+sc9wsFr7pGo9SFzQ78UlcWYK2Gu2FxlMjonhka5hvo4zvg
 WxlpXKEkaFt3gLd92m/dMqBrHfafH7VwOJY2zT3WIpjwuk0ZzmRg5p0pG/svVQEH
 NZmwRwlopysbR69B/n1nefJ84UO50fLh5s5Zr3gBRwbWNZyzhXk=
 -----END RSA PRIVATE KEY-----
--- a/Hands-on/src/setup
+++ b/Hands-on/src/setup
@ -0,0 +1,16 @@
 #!/bin/bash
 # download latest release
 wget -O /tmp/openssl-3.3.1.tar.gz https://github.com/openssl/openssl/releases/download/openssl-3.3.1/openssl-3.3.1.tar.gz
 # unpack source
 tar -xzvf /tmp/openssl-3.3.1.tar.gz -C /home/syssec/
 cd /home/syssec/openssl-3.3.1
 # build from source with static linking options
 ./config --prefix=/usr/local/openssl-3.3.1 --static -static -fPIC
 make -j6
 # install openssl
 sudo make install
--- a/Hands-on/src/simulate
+++ b/Hands-on/src/simulate
@ -0,0 +1,74 @@
 #!/usr/bin/env sh
 set -u
 # colors
 RED='\033[0;31m'
 GREEN='\033[0;32m'
 NC='\033[0m'
 # helper function
 print_and_execute() {
    local color=$1
    shift
    echo "⚡ ${color}$@${NC}"
    eval "$@"
    return $?
 }
 # setup 
 TMP=/tmp/signatureproxy
 KEYDIR=../employee_keys
 mkdir -p $TMP
 ########### Disclaimer #################
 # Die Story wurde von ChatGPT erstellt #
 ########################################
 # simulation
 print_and_execute "$GREEN" "./signatureproxy proxysetup -pkey $TMP/proxy_private.bin > $TMP/proxy_public.pem"
 echo "At Embedded Solutions Inc., security was paramount. The company specialized in creating firmware for a wide range of embedded devices used in critical industries, from medical equipment to automotive systems. To protect their firmware, they had implemented a sophisticated signature proxy system using Intel's SGX enclave technology."
 echo "One bright morning, Alice, a senior engineer known for her meticulous work, arrived at her desk. She was tasked with signing the latest stable version of a critical medical device firmware that she had finished the previous night."
 echo "With the proxy ready, Alice compiled their latest stable version. This firmware would soon run on life-saving medical devices, a fact that weighed heavily on her as she meticulously checked every detail."
 print_and_execute "$GREEN" "dd if=/dev/urandom of=$TMP/firmware.bin bs=1M count=1 2> /dev/null"
 echo "Once satisfied with the build, Alice signed the firmware with her private key as an assurance to the company that the firmware came from a trusted source."
 print_and_execute "$GREEN" "./signatureproxy employee -ekey $KEYDIR/alice_private.pem -firm $TMP/firmware.bin > $TMP/signature_alice.der"
 echo "The firmware, along with Alice's signature, was then sent to the signature proxy. The proxy, acting as a vigilant guardian, verified Alice's signature against a list of authorized keys. Her identity confirmed, the proxy resigned the firmware with its own private key."
 print_and_execute "$GREEN" "cat $TMP/signature_alice.der | ./signatureproxy proxy -pkey $TMP/proxy_private.bin -epub $KEYDIR/alice_public.pem -firm $TMP/firmware.bin > $TMP/signature_for_alice.der"
 echo "The final step was crucial: verifying the signed firmware to ensure it was ready for deployment. The team couldn't afford any mistakes, knowing the firmware's destination were life-saving medical devices."
 print_and_execute "$GREEN" "cat $TMP/signature_for_alice.der | ./signatureproxy embedded -ppub $TMP/proxy_public.pem -firm $TMP/firmware.bin > /dev/null"
 echo "\nMeanwhile, in a dark corner of the tech world, Oskar, a disgruntled former employee, was plotting his revenge. He had managed to get his hands on an old private key. With malicious intent, he set out to sign a modified version of the firmware, hoping to bypass the security measures."
 echo "Oskar, driven by his vendetta, signed the firmware with his old private key, intending to trick the system and cause havoc."
 print_and_execute "$RED" "./signatureproxy employee -ekey $KEYDIR/oskar_private.pem -firm $TMP/firmware.bin > $TMP/signature_oskar.der"
 echo "With a smug grin, he tried to pass his signed firmware through the proxy. But the system was built to withstand such threats. The proxy, ever vigilant, scrutinized the incoming data."
 print_and_execute "$RED" "cat $TMP/signature_oskar.der | ./signatureproxy proxy -pkey $TMP/proxy_private.bin -epub $KEYDIR/oskar_public.pem -firm $TMP/firmware.bin > $TMP/signature_for_oskar.der"
 status=$?
 if [ $status -eq 0 ]; then
    echo "Oskar's firmware signing attempt seemed successful. :("
    exit 1
 else
    echo "The proxy detected Oskar's unauthorized key and rejected the firmware. His malicious intent was thwarted, and the firmware remained secure."
 fi
 echo "With Oskar's attempt foiled, Embedded Solutions could breathe a sigh of relief. The integrity of their firmware was intact, safeguarded by the robust security measures of their signature proxy system. Alice and her team could continue their work with confidence, knowing that their systems were safe from internal and external threats."
 echo "\nIn the meantime, Bob, another trusted engineer, was working on a firmware update for the automotive sector. This update was equally critical and needed the same level of security scrutiny."
 print_and_execute "$GREEN" "dd if=/dev/urandom of=$TMP/firmware2.bin bs=1M count=1 2> /dev/null"
 echo "Bob finished his work and, following the security protocols, signed the new firmware with his private key."
 print_and_execute "$GREEN" "./signatureproxy employee -ekey $KEYDIR/bob_private.pem -firm $TMP/firmware2.bin > $TMP/signature_bob.der"
 echo "The signed firmware was then sent to the signature proxy. As expected, the proxy verified Bob's signature and signed the firmware with its private key, ensuring the update's authenticity."
 print_and_execute "$GREEN" "cat $TMP/signature_bob.der | ./signatureproxy proxy -pkey $TMP/proxy_private.bin -epub $KEYDIR/bob_public.pem -firm $TMP/firmware2.bin > $TMP/signature_for_bob.der"
 echo "The final verification process confirmed that Bob's firmware update was secure and ready for deployment."
 print_and_execute "$GREEN" "cat $TMP/signature_for_bob.der | ./signatureproxy embedded -ppub $TMP/proxy_public.pem -firm $TMP/firmware2.bin > /dev/null"
 echo "This concludes the story of Alice, Oskar, Bob, and the secure firmware signing process at Embedded Solutions Inc. Through the diligent efforts of trusted employees and advanced security technology, the integrity and safety of their embedded devices were preserved."
--- a/flake.nix
+++ b/flake.nix
@ -16,7 +16,7 @@
        "aarch64-linux"
      ] (system: function {
        inherit system;
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = import nixpkgs { inherit system; overlays = [ self.overlay ]; };
      });
    forAllAssignments = function:
@ -25,8 +25,12 @@
    texPackages = pkgs: pkgs.texlive.combine {
        inherit (pkgs.texlive) scheme-full latex-bin latexmk;
      };
    lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
    version = builtins.substring 0 8 lastModifiedDate;
  in rec {
-    packages = forAllSystems({system, pkgs}: forAllAssignments(assignment: let
+    packages = 
      forAllSystems({system, pkgs}: forAllAssignments(assignment: let
        tex = texPackages pkgs;
        document = pkgs.stdenvNoCC.mkDerivation rec {
          name = assignment;
@ -48,6 +52,7 @@
        };
      in document) // {
        default = packages.${system}.${pkgs.lib.last assignments};
        "Assignment 7" = pkgs.signatureProxy;
      });
    devShells = forAllSystems({pkgs, ...}: let
@ -58,7 +63,40 @@
      };
    });
-    hydraJobs = packages;
+    overlay = final: prev: with final; {
        signatureProxy = stdenv.mkDerivation {
            pname = "SignatureProxy";
            inherit version;
            src = ./7-SGX_Hands-on;
            buildScript = ''
                make
            '';
            installScript = ''
                mkdir -p $out/bin
                cp app $out/bin
                cp enclave.so $out/bin
            '';
            nativeBuildInputs = with pkgs; [
                clang
                glibc
                sgx-sdk
                gmp.dev
                openssl.dev
                pkg-config
            ];
            env = {
                SGX_SDK = pkgs.sgx-sdk;
                SGX_MODE = "SIM";
            };
        };
    };
  };
 }