OpenSSL签名未在Java中进行验证

I have a mobile application written in Objective C (iOS) which I need to generate signatures for the server to verify using the public key provided previously.

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，以便使用之前提供的公钥进行验证。

I'm struggling to get signatures to verify that are created by OpenSSL on my mobile application. I have Java to Java communication working and creating valid signatures, I just cannot get OpenSSL to create ones that are valid. There is a possibility my Java algorithm is incorrect but at this stage I'm fairly new to this.

我很难获得签名来验证OpenSSL是否在我的移动应用程序上创建。我有Java到Java通信工作和创建有效的签名，我只是不能让OpenSSL创建有效的。我的Java算法有可能是不正确的，但在这个阶段我对此很新。

Here is my OpenSSL code for generating a signature:

这是我用于生成签名的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;

}

You will see that I am actually using the string representation of the SHA256 hash - not the binary - this is on purpose. I then take that string and then sign it.

您将看到我实际上正在使用SHA256哈希的字符串表示 - 而不是二进制 - 这是故意的。然后，我接受该字符串，然后签名。

Now here is the Java code to verify the signature:

现在这里是验证签名的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))
  }

Everything seems to be correct (I have manually validated the Private Key/Public Key pairs) and if I sign the same data using Java it will then verify (as follows):

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）：

  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);
    }

I'm really at a dead end here, I've tried all the various changing the RSA_sign method to use NID_sha256 on its own and other permutations, but at this stage I'm just guessing. I would appreciate some assistance if someone has done this kind of thing successfully before.

我真的在这里死路一条，我已经尝试了所有各种改变RSA_sign方法以使用NID_sha256本身和其他排列，但在这个阶段我只是在猜测。如果有人之前已成功完成此类事情，我将不胜感激。

1 个解决方案

#1

OK so I don't exactly know why this is any different from the RSA_sign method but after testing openssl_verify() and openssl_sign() in PHP and those functions were producing the correct results for the signatures created in Java I decided to read through the PHP source code to figure out how they do it. Anyway, PHP uses functions with EVP_ prefix (high level cryptographic functions according to OpenSSL documentation). Anyway, I adjusted to Objective C code to instead use these functions and now my signatures are matching in all languages. I hope this helps someone.

好的，所以我不知道为什么这与RSA_sign方法有什么不同，但是在PHP中测试了openssl_verify（）和openssl_sign（）并且这些函数为Java创建的签名产生了正确的结果后我决定通读PHP源代码，以弄清楚他们是如何做到的。无论如何，PHP使用具有EVP_前缀的函数（根据OpenSSL文档的高级加密函数）。无论如何，我调整了Objective C代码来改为使用这些函数，现在我的签名在所有语言中都是匹配的。我希望这可以帮助别人。

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;

}