Assignment 7 - SGX Hands-on/src/enclave/enclave.c

@@ -92,49 +92,39 @@ 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(uint8_t *sealed, uint32_t *sealed_size, sgx_ec256_private_t *private, sgx_ec256_public_t *public) {
+sgx_status_t unseal_key_pair(const uint8_t *sealed, sgx_ec256_private_t *private, sgx_ec256_public_t *public) {
-    // handle missing sealed data
+    // invalid parameter handling
-    if((sealed == NULL) || (sealed_size == 0))
+    if(sealed == NULL) {
-        return SGX_ERROR_UNEXPECTED;
+        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 != 2*SGX_ECP256_KEY_SIZE) || (sk_size != SGX_ECP256_KEY_SIZE))
+    if ((pk_size != PK_SIZE) || (sk_size != SK_SIZE)) {
         return SGX_ERROR_UNEXPECTED;
-
-    // allocate memory for public and secret key
-    uint8_t *pk =(uint8_t *)malloc(pk_size);
-    uint8_t *sk =(uint8_t *)malloc(pk_size);
-    if((pk == NULL) || (sk == NULL)) {
-        free(pk);
-        free(sk);
-        return SGX_ERROR_OUT_OF_MEMORY;
     }
 
     // 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) {
-        free(pk);
-        free(sk);
         return status;
     }
 
     // copy buffers into key structs
     if(public != NULL) {
-        memcpy(public->gx, pk, SGX_ECP256_KEY_SIZE);
+        memcpy(public->gx, pk, PK_SIZE);
-        memcpy(public->gy, pk + SGX_ECP256_KEY_SIZE, SGX_ECP256_KEY_SIZE);
     }
     if (private != NULL) {
-        memcpy(private->r, sk, SGX_ECP256_KEY_SIZE);
+        memcpy(private->r, sk, SK_SIZE);
     }
 
-    // free temporary buffers
-    free(pk);
-    free(sk);
-
     // return success
-    return SGX_SUCCESS;
+    return status;
 }
 
 sgx_status_t public_key(const uint8_t *sealed, const size_t sealed_size, uint8_t *gx, uint8_t *gy) {