From 4aefc416e354d4eb3114b6715fcdfea8598b9f66 Mon Sep 17 00:00:00 2001
From: Sascha Tommasone <sascha@tommasone.me>
Date: Tue, 2 Jul 2024 23:18:26 +0200
Subject: [PATCH] [Assignment-7] sign_firmware: removed dynamic memory
 allocations; added sealing of key after creation; uint8_t *sealed is now two
 way pointer; improved error handling

---
 .../src/enclave/enclave.c                     | 36 +++++++++----------
 .../src/enclave/enclave.edl                   |  2 +-
 .../src/enclave/enclave.h                     |  2 +-
 3 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/Assignment 7 - SGX Hands-on/src/enclave/enclave.c b/Assignment 7 - SGX Hands-on/src/enclave/enclave.c
index 86441a9..2e36ba8 100644
--- a/Assignment 7 - SGX Hands-on/src/enclave/enclave.c	
+++ b/Assignment 7 - SGX Hands-on/src/enclave/enclave.c	
@@ -150,17 +150,14 @@ sgx_status_t get_public_key(const uint8_t *sealed, uint32_t sealed_size, uint8_t
     return status;
 }
 
-sgx_status_t sign_firmware(const uint8_t *sealed, size_t sealed_size, uint8_t *data, size_t data_size, uint8_t *signature, size_t signature_size) {
-    // handle missing sealed buffer
-    if((sealed == NULL) || (sealed_size == 0)) {
-        return SGX_ERROR_UNEXPECTED;
+sgx_status_t sign_firmware(const uint8_t *data, uint32_t data_size, uint8_t *sealed, uint32_t sealed_size, uint8_t *signature, uint32_t signature_size) {
+    // invalid parameter handling
+    if((data == NULL) || (data_size == 0)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if((sealed == NULL) || (sealed_size == 0)) {
+        return SGX_ERROR_INVALID_PARAMETER;
     }
     
-    // handle missing firmware buffer
-    if((data == NULL) || (data_size == 0)) {
-        return SGX_ERROR_UNEXPECTED;
-    }
-
     // declare need structures
     sgx_ecc_state_handle_t ecc_handle;
     sgx_ec256_private_t private;
@@ -174,32 +171,31 @@ sgx_status_t sign_firmware(const uint8_t *sealed, size_t sealed_size, uint8_t *d
 
     // try unseal keypair
     sgx_status_t seal_status;
-    if(seal_status = unseal_key_pair(sealed, &sealed_size, &private, NULL) != SGX_SUCCESS) {
+    if(seal_status = unseal_key_pair(sealed, &private, NULL) != SGX_SUCCESS) {
         if((status = sgx_ecc256_create_key_pair(&private, &public, ecc_handle)) != SGX_SUCCESS) {
             sgx_ecc256_close_context(ecc_handle);
             return status;
         }
     }
-    
+
     // create signature
     sgx_ec256_signature_t ecc_signature;
     if((status = sgx_ecdsa_sign(data, data_size, &private, &ecc_signature, ecc_handle)) != SGX_SUCCESS) {
         sgx_ecc256_close_context(ecc_handle);
         return status;
     }
-    
+
+    // TODO: possible wrong endianess for other programms
     // copy signature to return buffer
-    // TODO: endian swap
     if((signature == NULL) || (signature_size == 0)) {
         sgx_ecc256_close_context(ecc_handle);
-        return SGX_ERROR_UNEXPECTED;
+        return SGX_ERROR_INVALID_PARAMETER;
     }
-    memcpy(signature, ecc_signature.x, SGX_ECP256_KEY_SIZE);
-    memcpy(signature + SGX_ECP256_KEY_SIZE, ecc_signature.y, SGX_ECP256_KEY_SIZE);
-    
-    if(seal_status != SGX_SUCCESS) {
-        seal_status = seal_key_pair(&private, &public, sealed, &sealed_size);
-        // TODO: return sealed keypair
+    memcpy(signature, ecc_signature.x, SI_SIZE);
+
+    // seal the key
+    if((seal_status != SGX_SUCCESS) && (sealed != NULL)) {
+        seal_status = seal_key_pair(&private, &public, &sealed, sealed_size);
     }
 
     // close ecc handle and return success
diff --git a/Assignment 7 - SGX Hands-on/src/enclave/enclave.edl b/Assignment 7 - SGX Hands-on/src/enclave/enclave.edl
index 8a930bd..978b9d7 100644
--- a/Assignment 7 - SGX Hands-on/src/enclave/enclave.edl	
+++ b/Assignment 7 - SGX Hands-on/src/enclave/enclave.edl	
@@ -45,7 +45,7 @@ enclave {
         public int get_public_key_size();
         public int get_private_key_size();
         public sgx_status_t get_public_key([in, size=sealed_size]const uint8_t *sealed, uint32_t sealed_size, [out, size=gx_size]uint8_t *gx, uint32_t gx_size, [out, size=gx_size]uint8_t *gy, uint32_t gy_size);
-        public sgx_status_t sign_firmware([in, size=data_size]const uint8_t *sealed, size_t sealed_size, [in, size=data_size]uint8_t *data, size_t data_size, [out, size=signature_size]uint8_t *signature, size_t signature_size);
+        public sgx_status_t sign_firmware([in, size=data_size]const uint8_t *data, uint32_t data_size, [in, out, size=sealed_size]uint8_t *sealed, uint32_t sealed_size, [out, size=signature_size]uint8_t *signature, uint32_t signature_size);
     };
 
     /* 
diff --git a/Assignment 7 - SGX Hands-on/src/enclave/enclave.h b/Assignment 7 - SGX Hands-on/src/enclave/enclave.h
index 77dce7b..1901aba 100644
--- a/Assignment 7 - SGX Hands-on/src/enclave/enclave.h	
+++ b/Assignment 7 - SGX Hands-on/src/enclave/enclave.h	
@@ -45,6 +45,6 @@ int get_public_key_size();
 int get_private_key_size();
 
 sgx_status_t get_public_key(const uint8_t *sealed, const uint32_t sealed_size, uint8_t *gx, uint32_t gx_size, uint8_t *gy, uint32_t gy_size);
-sgx_status_t sign_firmware(const uint8_t *sealed, size_t sealed_size, uint8_t *data, size_t data_size, uint8_t *signature, size_t signature_size);
+sgx_status_t sign_firmware(const uint8_t *data, uint32_t data_size, uint8_t *sealed, uint32_t sealed_size, uint8_t *signature, uint32_t signature_size);
 
 #endif /* !_ENCLAVE_H_ */
\ No newline at end of file