[Assignment-7] add prototype 'sgx_status_t public_key'

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

@@ -3,11 +3,44 @@
 #include <sgx_error.h>
 #include <sgx_tcrypto.h>
 
-const unsigned char *secretkey_file = "/var/signrelay/sk";
+sgx_status_t public_key(const uint8_t *sealed, const size_t sealed_size, uint8_t *gx, uint8_t *gy) {
-const unsigned char *publickey_file = "/var/signrelay/pk";
+    // return if no sealed data provided
+    if(sealed == NULL)
+        return SGX_ERROR_UNEXPECTED;
     
-sgx_status_t public_key(uint8_t *gx, uint8_t *gy) {
+    // calculate public_key size and return error for unexpected results
-    // TODO
+    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))
+        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 public key into return buffers
+    if((gx != NULL) && (gy != NULL)) {
+        memcpy(gx, pk, SGX_ECP256_KEY_SIZE);
+        memcpy(gy, pk + SGX_ECP256_KEY_SIZE, SGX_ECP256_KEY_SIZE);
+    }
+
+    // free allocated memory and return success
+    free(pk);
+    free(sk);
+    return SGX_SUCCESS;
 }
 
 sgx_status_t sign_firmware(uint8_t *data, size_t data_size, uint8_t *signature, size_t signature_size) {

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

@@ -40,7 +40,7 @@ enclave {
      */
     
     trusted {
-        public sgx_status_t public_key([out]uint8_t *gx, [out]uint8_t *gy);
+        public sgx_status_t public_key([in, size=sealed_size]const uint8_t *sealed, size_t sealed_size, [out]uint8_t *gx, [out]uint8_t *gy);
         public sgx_status_t sign_firmware([in, size=data_size]uint8_t *data, size_t data_size, [out, size=signature_size]uint8_t *signature, size_t signature_size);
     };
 
@@ -50,6 +50,6 @@ enclave {
      *  [string]: specifies 'str' is a NULL terminated buffer.
      */
     untrusted {
-        
+        int read_file([in, string] path_to_file, [out, size=bsize] uint8_t *buffer, size_t bsize);
     };
 };

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

@@ -37,7 +37,7 @@
 #include <assert.h>
 #include <sgx_error.h>
 
-sgx_status_t public_key(uint8_t *gx, uint8_t *gy);
+sgx_status_t public_key(const uint8_t *sealed, const size_t sealed_size, uint8_t *gx, uint8_t *gy);
 sgx_status_t sign_firmware(uint8_t *data, size_t data_size, uint8_t *signature, size_t signature_size);
 
 #endif /* !_ENCLAVE_H_ */