java - OpenSSL 签名未在 Java 中验证

Question

我有一个用 Objective C (iOS) 编写的移动应用程序，我需要为服务器生成签名以使用之前提供的公钥进行验证。

我正在努力获取签名以验证它们是由 OpenSSL 在我的移动应用程序上创建的。我有 Java 到 Java 的通信工作并创建有效的签名，我只是无法让 OpenSSL 创建有效的签名。有可能我的 Java 算法不正确，但在这个阶段我对此还很陌生。

这是我生成签名的 OpenSSL 代码:

RCT_EXPORT_METHOD(signDataWithKey:(NSString *)dataToSign
                  privateKey:(NSString *)privateKey
                  callback:(RCTResponseSenderBlock)callback)
{
  int retEr;
  char* text = (char*) [dataToSign UTF8String];
  unsigned char *data;
  unsigned long dataLen;

  // converting nsstring base64 private key to openssl RSA key

  BIO *mem = NULL;
  RSA *rsa_private = NULL;
  char *private_key = (char*)[privateKey UTF8String];

  NSLog(@"Processing private key %s", private_key);

  mem = BIO_new_mem_buf(private_key, strlen(private_key));
  if (mem == NULL)
  {
    char buffer[120];
    ERR_error_string(ERR_get_error(), buffer);
    NSLog(@"Error loading private key %s", buffer);
  }

  rsa_private = PEM_read_bio_RSAPrivateKey(mem, NULL, NULL, NULL);
  BIO_free (mem);
  if (rsa_private == NULL)
  {
    char buffer[120];
    ERR_error_string(ERR_get_error(), buffer);
    NSLog(@"OpenSSL error: %s", buffer);
  } else {
    NSLog(@"Successfully loaded private key");
  }
  // end of convertion

  data = (unsigned char *) text;
  dataLen = strlen(text);


  //// creating signature
  // sha256
  unsigned char hash[SHA256_DIGEST_LENGTH];
  unsigned char sign[256];
  unsigned int signLen;



  SHA256(data, dataLen, hash);

  unsigned char *shaString = sha256_hash_string(hash);

  NSData* plainData = [NSData dataWithBytes:(const void *)shaString length:strlen(shaString)];
  NSString *base64String = [plainData base64EncodedStringWithOptions:0];

  NSLog(@"Base64 checksum %@", base64String);

  NSLog(@"SHA256 of %s is %send", text, shaString);


  //  signing
  retEr = RSA_sign(NID_sha256WithRSAEncryption, shaString, strlen(shaString), sign, &signLen, rsa_private);
  NSData* signatureData = [NSData dataWithBytes:(const void *)sign length:signLen];
  NSString *base64Signature = [signatureData base64EncodedStringWithOptions:0];
  NSLog(@"Got signed data %@", base64Signature);


  //  printf("Signature len gth = %d\n", signLen);
  NSLog(@"RSA_sign: %@ signature length = %u", (retEr == 1) ? @"RSA_sign success": @"RSA_sign error", signLen);

  NSLog(@"Got signed data %@", base64Signature);


  RSA_free(rsa_private);
  callback(@[base64Signature]);
}

unsigned char *sha256_hash_string (unsigned char hash[SHA256_DIGEST_LENGTH])
{
  unsigned char *outputBuffer = calloc(65, sizeof(char));

  int i = 0;

  for(i = 0; i < SHA256_DIGEST_LENGTH; i++)
  {
    sprintf(outputBuffer + (i * 2), "%02x", hash[i]);
  }

  outputBuffer[64] = 0;

  return outputBuffer;

}

您会看到我实际上使用的是 SHA256 哈希的字符串表示形式——而不是二进制——这是故意的。然后我拿走那个字符串并签名。

下面是验证签名的Java代码:

public static boolean verifySignature(PublicKey publicKey, byte[] signedData, String signature) {
      java.security.Security.addProvider(
              new org.bouncycastle.jce.provider.BouncyCastleProvider()
      );
      Signature signatureCheck = Signature.getInstance("SHA256withRSA", "BC");
      signatureCheck.initVerify(publicKey);
      signatureCheck.update(signedData);

      return signatureCheck.verify(CryptoUtil.Base64Decode(signature))
  }

一切似乎都是正确的(我已经手动验证了私钥/公钥对)，如果我使用 Java 签署相同的数据，它将验证(如下所示):

  public static String getSignatureForString(PrivateKey privateKey, String data) {
        Signature signature = Signature.getInstance("SHA256withRSA", "BC");
        signature.initSign(privateKey);

        signature.update(data.getBytes());

        byte[] signed = signature.sign();

        return CryptoUtil.Base64Encode(signed);
    }

我真的走到了死胡同，我已经尝试了所有各种更改 RSA_sign 方法以单独使用 NID_sha256 和其他排列，但在这个阶段我只是猜测。如果有人以前成功做过这种事情，我将不胜感激。

Answer 1

好的，所以我不完全知道为什么这与 RSA_sign 方法有任何不同，但在 PHP 中测试 openssl_verify() 和 openssl_sign() 并且这些函数为在 Java 中创建的签名生成正确的结果后，我决定阅读通过PHP源代码弄清楚他们是怎么做到的。无论如何，PHP 使用带有 EVP_ 前缀的函数(根据 OpenSSL 文档的高级加密函数)。不管怎样，我调整到 Objective C 代码来代替使用这些函数，现在我的签名在所有语言中都是匹配的。我希望这对某人有所帮助。

RCT_EXPORT_METHOD(signDataWithKey:(NSString *)dataToSign
                  privateKey:(NSString *)privateKey
                  callback:(RCTResponseSenderBlock)callback)
{
  int retEr;
  char* text = (char*) [dataToSign UTF8String];
  unsigned char *data;
  unsigned long dataLen;

  // converting nsstring base64 private key to openssl RSA key

  BIO *mem = NULL;
  EVP_PKEY *pkey;
  char *private_key = (char*)[privateKey UTF8String];

  EVP_MD_CTX md_ctx;

  NSLog(@"Processing private key %s", private_key);


  mem = BIO_new_mem_buf(private_key, strlen(private_key));
  if (mem == NULL)
  {
    char buffer[120];
    ERR_error_string(ERR_get_error(), buffer);
    NSLog(@"Error loading private key %s", buffer);
  }

  // CHANGED
  pkey = PEM_read_bio_PrivateKey(mem, NULL, NULL, NULL);

  BIO_free (mem);
  if (pkey == NULL)
  {
    char buffer[120];
    ERR_error_string(ERR_get_error(), buffer);
    NSLog(@"OpenSSL error: %s", buffer);
  } else {
    NSLog(@"Successfully loaded private key");
  }
  // end of convertion

  data = (unsigned char *) text;
  dataLen = strlen(text);


  //// creating signature
  // sha256
  unsigned char hash[SHA256_DIGEST_LENGTH];
  unsigned char sign[4096];
  int signLen;



  SHA256(data, dataLen, hash);

  unsigned char *shaString = sha256_hash_string(hash);

  NSData* plainData = [NSData dataWithBytes:(const void *)shaString length:strlen(shaString)];
  NSString *base64String = [plainData base64EncodedStringWithOptions:0];

  NSLog(@"Base64 checksum %@", base64String);

  NSLog(@"SHA256 of %s is %s end", text, shaString);

  // CHANGED - Using EVP to sign now.
  EVP_SignInit(&md_ctx, EVP_sha256());
  EVP_SignUpdate(&md_ctx, shaString, strlen(shaString));
  retEr = EVP_SignFinal(&md_ctx, sign, &signLen, pkey);


  //  OLD METHOD
  //retEr = RSA_sign(NID_sha256WithRSAEncryption, shaString, strlen(shaString), sign, &signLen, rsa_private);


  NSData* signatureData = [NSData dataWithBytes:(const void *)sign length:signLen];
  NSString *base64Signature = [signatureData base64EncodedStringWithOptions:0];
  NSLog(@"Got signed data %@", base64Signature);


  //  printf("Signature len gth = %d\n", signLen);
  NSLog(@"RSA_sign: %@ signature length = %u", (retEr == 1) ? @"RSA_sign success": @"RSA_sign error", signLen);

  NSLog(@"Got signed data %@", base64Signature);


  EVP_PKEY_free(pkey);
  callback(@[base64Signature]);
}

unsigned char *sha256_hash_string (unsigned char hash[SHA256_DIGEST_LENGTH])
{
  unsigned char *outputBuffer = calloc(65, sizeof(char));

  int i = 0;

  for(i = 0; i < SHA256_DIGEST_LENGTH; i++)
  {
    sprintf(outputBuffer + (i * 2), "%02x", hash[i]);
  }

  outputBuffer[64] = 0;

  return outputBuffer;

}