在C ++中通过OpenSSL使用公钥验证JWT令牌时出现分段错误

时间：2019-05-18 15:40:54

标签： c++ openssl jwt

我对C ++和OpenSSL非常陌生。我必须通过C ++中的OpenSSL使用公钥来验证给定的JWT令牌（算法RS256）。我正在使用以下算法来验证JWT令牌。

// signature algorithm data = base64urlEncode( header ) + “.” + base64urlEncode( payload ) hashedData = hash( data, secret ) signature = base64urlEncode( hashedData )

我在Mac系统上，正在使用g ++编译我的代码。终端上的openssl version显示LibreSSL 2.6.5。

// Assume that base64 encode and decode functions are available
bool RSAVerifySignature( RSA* rsa, std::string token, std::string pub_key) {

  std::vector<std::string> tokenParts;
  split(token, tokenParts, '.');

  std::string decoded_header = tokenParts[0];
  std::string header = base64_encode(reinterpret_cast<const unsigned char*>(decoded_header.c_str()),
    decoded_header.length());

  std::string decoded_body = tokenParts[1];
  std::string body = base64_encode(reinterpret_cast<const unsigned char*>(decoded_body.c_str()),
    decoded_body.length());


  std::string sig = tokenParts[2];

  EVP_PKEY* pubKey  = EVP_PKEY_new();
  EVP_PKEY_assign_RSA(pubKey, rsa);
  EVP_MD_CTX* m_RSAVerifyCtx = EVP_MD_CTX_create();

  if (1 != EVP_DigestVerifyInit(m_RSAVerifyCtx, NULL, EVP_sha256(), NULL, pubKey)) {
      printf("verify init failed....\n");
  } else {
      printf("verify init passed....\n");
  }
  if (1 != EVP_DigestVerifyUpdate(m_RSAVerifyCtx, (unsigned char *)header.data(), header.length())) {
      printf("DigestVerifyUpdate for header failed....\n");
  } else {
          printf("DigestVerifyUpdate for header passed....\n");
  }
  if (1 != EVP_DigestVerifyUpdate(m_RSAVerifyCtx, ".", 1)) {
      printf("DigestVerifyUpdate for dot failed\n");
  } else {
      printf("DigestVerifyUpdate for dot passed\n");
  }
  if (1 != EVP_DigestVerifyUpdate(m_RSAVerifyCtx, (unsigned char *)body.data(), body.length())) {
      printf("DigestVerifyUpdate for body failed\n");
  } else {
      printf("DigestVerifyUpdate for body passed\n");
  }

  int result = EVP_DigestVerifyFinal(m_RSAVerifyCtx, (unsigned char *)sig.data(), sig.length());
  return result;
}

RSA* createPublicRSA(std::string key) {
  RSA *rsa = NULL;
  BIO *keybio;
  const char* c_string = key.c_str();
  keybio = BIO_new_mem_buf((void*)c_string, -1);
  if (keybio==NULL) {
      return 0;
  }
  rsa = PEM_read_bio_RSA_PUBKEY(keybio, &rsa,NULL, NULL);
  return rsa;
}

int main()
{
    std::string token = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImlhdCI6MTUxNjIzOTAyMn0.POstGetfAytaZS82wHcjoTyoqhMyxXiWdR7Nn7A29DNSl0EiXLdwJ6xC6AfgZWF1bOsS_TuYI3OG85AmiExREkrS6tDfTQ2B3WXlrr-wp5AokiRbz3_oB4OxG-W9KcEEbDRcZc0nH3L7LzYptiy1PtAylQGxHTWZXtGz4ht0bAecBgmpdgXMguEIcoqPJ1n3pIWk_dUZegpqx0Lka21H6XxUTxiy8OcaarA8zdnPUnV6AmNP3ecFawIFYdvJB_cm-GvpCSbr8G8y_Mllj8f4x9nBH8pQux89_6gUY618iYv7tuPWBFfEbLxtF2pZS6YC1aSfLQxeNe8djT9YjpvRZA";

    std::string publicKey = "-----BEGIN PUBLIC KEY-----"\
"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnzyis1ZjfNB0bBgKFMSv"\
"vkTtwlvBsaJq7S5wA+kzeVOVpVWwkWdVha4s38XM/pa/yr47av7+z3VTmvDRyAHc"\
"aT92whREFpLv9cj5lTeJSibyr/Mrm/YtjCZVWgaOYIhwrXwKLqPr/11inWsAkfIy"\
"tvHWTxZYEcXLgAXFuUuaS3uF9gEiNQwzGTU1v0FqkqTBr4B8nW3HCN47XUu0t8Y0"\
"e+lf4s4OxQawWD79J9/5d3Ry0vbV3Am1FtGJiJvOwRsIfVChDpYStTcHTCMqtvWb"\
"V6L11BWkpzGXSW4Hv43qa+GSYOD2QU68Mb59oSk2OB+BtOLpJofmbGEGgvmwyCI9"\
"MwIDAQAB"\
"-----END PUBLIC KEY-----";

    RSA* publicRSA = createPublicRSA(publicKey);
    bool result = RSAVerifySignature(publicRSA, token, publicKey);
    return 0;
}

我在Segmentation fault: 11的电话中接到EVP_DigestVerifyFinal。我不知道我在哪里错。请帮忙。

2 个答案:

答案 0 :(得分：0)

如果您进行了一些基本的错误检查，您将看到createPublicRSA函数返回一个nullptr。这是因为PEM_read_bio_RSA_PUBKEY期望看到换行符，并且您的publicKey字符串没有任何内容。

如果将其更改为具有换行符，则应该能够创建RSA密钥。

例如

    std::string publicKey = "-----BEGIN PUBLIC KEY-----\n"\
"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnzyis1ZjfNB0bBgKFMSv\n"\
"vkTtwlvBsaJq7S5wA+kzeVOVpVWwkWdVha4s38XM/pa/yr47av7+z3VTmvDRyAHc\n"\
"aT92whREFpLv9cj5lTeJSibyr/Mrm/YtjCZVWgaOYIhwrXwKLqPr/11inWsAkfIy\n"\
"tvHWTxZYEcXLgAXFuUuaS3uF9gEiNQwzGTU1v0FqkqTBr4B8nW3HCN47XUu0t8Y0\n"\
"e+lf4s4OxQawWD79J9/5d3Ry0vbV3Am1FtGJiJvOwRsIfVChDpYStTcHTCMqtvWb\n"\
"V6L11BWkpzGXSW4Hv43qa+GSYOD2QU68Mb59oSk2OB+BtOLpJofmbGEGgvmwyCI9\n"\
"MwIDAQAB\n"\
"-----END PUBLIC KEY-----\n";

您的代码也将无法使用，因为您不需要“编码”标题和正文，但是您需要“ base64url解码”签名，因为它必须是二进制值才能生效。

以下代码对我有用：

bool RSAVerifySignature(RSA* rsa, std::string const& token)
{
    auto const pub_key_handle = make_handle(EVP_PKEY_new(), EVP_PKEY_free);
    if (!pub_key_handle)
    {
        RSA_free(rsa);
        return false;
    }
    EVP_PKEY_assign_RSA(pub_key_handle.get(), rsa);

    std::vector<std::string> token_parts;
    split(token, token_parts, '.');
    if (token_parts.size() != 3) return false;

    auto& decoded_header = token_parts[0];
    auto& decoded_body = token_parts[1];
    auto sig_decoded = base64_url_decode(token_parts[2]);

    auto const rsa_verify_ctx = make_handle(EVP_MD_CTX_create(), EVP_MD_CTX_free);
    if (!rsa_verify_ctx) return false;

    if (1 != EVP_DigestVerifyInit(rsa_verify_ctx.get(), nullptr, EVP_sha256(), nullptr, pub_key_handle.get())) return false;
    if (1 != EVP_DigestVerifyUpdate(rsa_verify_ctx.get(), reinterpret_cast<unsigned char*>(decoded_header.data()), decoded_header.length())) return false;
    if (1 != EVP_DigestVerifyUpdate(rsa_verify_ctx.get(), ".", 1)) return false;
    if (1 != EVP_DigestVerifyUpdate(rsa_verify_ctx.get(), reinterpret_cast<unsigned char*>(decoded_body.data()), decoded_body.length())) return false;
    return 1 == EVP_DigestVerifyFinal(rsa_verify_ctx.get(), reinterpret_cast<unsigned char*>(sig_decoded.data()), sig_decoded.length());
}

答案 1 :(得分：0)

通过CTX清理实现代码的安全性

bool sha_validate( const EVP_MD* type, const std::string& input, const std::vector<unsigned char>& digest )
{
    if( !rsa )
        return false;

    EVP_PKEY* pub_key  = EVP_PKEY_new(); 
    EVP_PKEY_assign_RSA(pub_key, rsa);
    EVP_MD_CTX* rsa_verify_ctx = EVP_MD_CTX_create();

    auto ctx_free = scope_remove( [rsa_verify_ctx]() {
        EVP_MD_CTX_cleanup( rsa_verify_ctx );
        EVP_MD_CTX_destroy( rsa_verify_ctx );
    });

    if (EVP_DigestVerifyInit( rsa_verify_ctx,NULL, type, NULL, pub_key  ) <=0 )
        return false;

    if (EVP_DigestVerifyUpdate( rsa_verify_ctx, input.c_str(), input.size() ) <= 0)
        return false;

    return EVP_DigestVerifyFinal( rsa_verify_ctx, &digest[0], digest.size() ) == 1;
}

bool sha_validate( int type, const std::string& input, const std::vector<unsigned char>& digest )
{
     bool result = false;

     if( type & RsaOaep::SHA1 )
         result = sha_validate( EVP_sha1(), input, digest );

     if( !result && ( type & RsaOaep::SHA256 ) == static_cast<int>(RsaOaep::SHA256) )
         result = sha_validate( EVP_sha256(), input, digest );

     return result;
}

RSA* rsa = nullptr;
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