/*
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* verifier.cpp
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*
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* Created on: Nov 16, 2019
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* Author: GC
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*/
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#include <openssl/pem.h>
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#include <openssl/err.h>
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#include <stdlib.h>
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#include <errno.h>
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#ifdef _WIN32
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#include <windows.h>
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#endif
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#include <public_key.h>
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#include "../signature_verifier.hpp"
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#include "../../base/logger.h"
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namespace license {
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namespace os {
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static void free_resources(EVP_PKEY* pkey, EVP_MD_CTX* mdctx) {
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if (pkey) {
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EVP_PKEY_free(pkey);
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}
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if (mdctx) {
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EVP_MD_CTX_destroy(mdctx);
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}
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}
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static void initialize() {
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static int initialized = 0;
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if (initialized == 0) {
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initialized = 1;
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ERR_load_ERR_strings();
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ERR_load_crypto_strings();
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OpenSSL_add_all_algorithms();
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}
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}
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FUNCTION_RETURN verify_signature(const std::string& stringToVerify, const std::string& signatureB64) {
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EVP_MD_CTX* mdctx = NULL;
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const unsigned char pubKey[] = PUBLIC_KEY;
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int func_ret = 0;
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initialize();
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BIO* bio = BIO_new_mem_buf((void*)(pubKey), sizeof(pubKey));
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RSA* rsa = d2i_RSAPublicKey_bio(bio, NULL);
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BIO_free(bio);
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if (rsa == NULL) {
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LOG_ERROR("Error reading public key");
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return FUNC_RET_ERROR;
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}
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EVP_PKEY* pkey = EVP_PKEY_new();
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EVP_PKEY_assign_RSA(pkey, rsa);
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/*BIO* bo = BIO_new(BIO_s_mem());
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BIO_write(bo, pubKey, strlen(pubKey));
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RSA *key = 0;
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PEM_read_bio_RSAPublicKey(bo, &key, 0, 0);
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BIO_free(bo);*/
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// RSA* rsa = EVP_PKEY_get1_RSA( key );
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// RSA * pubKey = d2i_RSA_PUBKEY(NULL, <der encoded byte stream pointer>, <num bytes>);
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unsigned char buffer[512];
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BIO* b64 = BIO_new(BIO_f_base64());
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BIO* encoded_signature = BIO_new_mem_buf((const void*)signatureB64.c_str(), signatureB64.size());
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BIO* biosig = BIO_push(b64, encoded_signature);
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BIO_set_flags(biosig, BIO_FLAGS_BASE64_NO_NL); // Do not use newlines to flush buffer
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unsigned int len = BIO_read(biosig, (void*)buffer, signatureB64.size());
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// Can test here if len == decodeLen - if not, then return an error
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buffer[len] = 0;
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BIO_free_all(biosig);
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/* Create the Message Digest Context */
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if (!(mdctx = EVP_MD_CTX_create())) {
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free_resources(pkey, mdctx);
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LOG_ERROR("Error creating context");
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return FUNC_RET_ERROR;
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}
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if (1 != EVP_DigestVerifyInit(mdctx, NULL, EVP_sha256(), NULL, pkey)) {
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LOG_ERROR("Error initializing digest");
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free_resources(pkey, mdctx);
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return FUNC_RET_ERROR;
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}
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func_ret = EVP_DigestVerifyUpdate(mdctx, (const void*)stringToVerify.c_str(), stringToVerify.size());
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if (1 != func_ret) {
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LOG_ERROR("Error verifying digest %d", func_ret);
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free_resources(pkey, mdctx);
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return FUNC_RET_ERROR;
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}
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FUNCTION_RETURN result;
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func_ret = EVP_DigestVerifyFinal(mdctx, buffer, len);
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if (1 != func_ret) {
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LOG_ERROR("Error verifying digest %d", func_ret);
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}
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result = (1 == func_ret ? FUNC_RET_OK : FUNC_RET_ERROR);
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free_resources(pkey, mdctx);
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return result;
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}
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} // namespace os
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} /* namespace license */
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