[Assignment-7] update verify_firmware

7-SGX_Hands-on/src/enclave/enclave.c

@@ -53,6 +53,17 @@
 #define SI_SIZE 2*SK_SIZE
 #endif
 
+const sgx_ec256_public_t authorized[2] = {
+    {
+        0,
+        0
+    },
+    {
+        0,
+        0
+    }
+};
+
 int get_sealed_size() {
     return sgx_calc_sealed_data_size(PK_SIZE, SK_SIZE);
 }
@@ -69,7 +80,7 @@ int get_private_key_size() {
     return SK_SIZE;
 }
 
-sgx_status_t seal_key_pair(sgx_ec256_private_t *private, sgx_ec256_public_t *public, uint8_t **sealed, uint32_t sealed_size) {
+static sgx_status_t seal_key_pair(sgx_ec256_private_t *private, sgx_ec256_public_t *public, uint8_t **sealed, uint32_t sealed_size) {
     // invalid parameter handling
     if((private == NULL) || (public == NULL))
         return SGX_ERROR_INVALID_PARAMETER;
@@ -92,7 +103,7 @@ sgx_status_t seal_key_pair(sgx_ec256_private_t *private, sgx_ec256_public_t *pub
     return sgx_seal_data(PK_SIZE, (const uint8_t *)pk, SK_SIZE, (const uint8_t *)sk, size, (sgx_sealed_data_t *) *sealed);
 }
 
-sgx_status_t unseal_key_pair(const uint8_t *sealed, sgx_ec256_private_t *private, sgx_ec256_public_t *public) {
+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;
@@ -150,15 +161,62 @@ 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 *data, uint32_t data_size, uint8_t *sealed, uint32_t sealed_size, uint8_t *signature, uint32_t signature_size) {
+static sgx_status_t verify_signature(const uint8_t *data, const uint32_t data_size, const sgx_ec256_public_t *public, const sgx_ec256_signature_t* ecc_signature) {
+    // invalid parameter handling
+    if((data == NULL) || (data_size == 0)) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if(public == NULL) {
+        return SGX_ERROR_INVALID_PARAMETER;
+    } else if(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(data, data_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 *data, uint32_t data_size, uint8_t *sealed, uint32_t sealed_size, const uint8_t *public_key, uint32_t public_key_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;
+    } else if((public_key == NULL) || (public_key_size != PK_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) {
+            continue;
+        }
+        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;
     sgx_ec256_public_t public;
@@ -169,6 +227,13 @@ sgx_status_t sign_firmware(const uint8_t *data, uint32_t data_size, uint8_t *sea
         return status;
     }
 
+    // verify request
+    /*
+    if((status = verify_signature(data, data_size, (const sgx_ec256_public_t *)public_key, (const sgx_ec256_signature_t *)signature)) != SGX_EC_VALID) {
+        sgx_ecc256_close_context(ecc_handle);
+        return status;
+    }*/
+
     // try unseal keypair
     sgx_status_t seal_status;
     if(seal_status = unseal_key_pair(sealed, &private, NULL) != SGX_SUCCESS) {
@@ -179,7 +244,6 @@ sgx_status_t sign_firmware(const uint8_t *data, uint32_t data_size, uint8_t *sea
     }
 
     // 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;
@@ -215,25 +279,15 @@ sgx_status_t verify_firmware(const uint8_t *data, uint32_t data_size, const uint
         return SGX_ERROR_INVALID_PARAMETER;
     }
 
-    // declare need structures
-    sgx_ec256_signature_t ecc_signature;
-    sgx_ecc_state_handle_t ecc_handle;
+    // declare needed structures
     sgx_ec256_public_t public;
+    sgx_status_t status;
 
     // invalid signature
     if(signature_size > SI_SIZE) {
         return SGX_ERROR_INVALID_PARAMETER;
     }
 
-    // open ecc handle
-    sgx_status_t status;
-    if((status = sgx_ecc256_open_context(&ecc_handle)) != SGX_SUCCESS) {
-        return status;
-    }
-
-    // copy signature into struct
-    memcpy(ecc_signature.x, signature, SI_SIZE);
-
     // verify signature from staff or enclave
     if(public_key != NULL) {
         // invalid public key
@@ -241,26 +295,20 @@ sgx_status_t verify_firmware(const uint8_t *data, uint32_t data_size, const uint
             return SGX_ERROR_INVALID_PARAMETER;
         }
 
+        // verification only with authorized public keys
+        for(size_t i = 0; i < sizeof(authorized)/sizeof(authorized[0]); i++) {
+
+        }
+
         // copy public key into struct
         memcpy(public.gx, public_key, PK_SIZE);
     } else {
         // unseal public key
-        if(unseal_key_pair(sealed, NULL, &public) != SGX_SUCCESS) {
-            sgx_ecc256_close_context(ecc_handle);
-            return SGX_ERROR_UNEXPECTED;
+        if((status = unseal_key_pair(sealed, NULL, &public)) != SGX_SUCCESS) {
+            return status;
         }
     }
 
-    // verify signature
-    uint8_t result;
-    sgx_status_t verification_status = sgx_ecdsa_verify((const uint8_t *)data, data_size, (const sgx_ec256_public_t *)&public, (const sgx_ec256_signature_t *)&ecc_signature, &result, ecc_handle);
-
-    // handle failed verification process
-    if(verification_status != SGX_SUCCESS) {
-        result = verification_status;
-    }
-
-    // close handle and return result
-    sgx_ecc256_close_context(ecc_handle);
-    return result;
-}
+    // verify signature and return result
+    return verify_signature(data, data_size, &public, (const sgx_ec256_signature_t *)signature);
+}