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，以便使用之前提供的公钥进行验证。

我很难获得签名来验证我的移动应用程序上是否由OpenSSL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。

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;

}

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。然后我接受那个字符串然后签名。

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))
  }

一切似乎都是正确的（我手动验证了私钥/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);
    }

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自己和其他排列，但在这个阶段我只是在猜测。如果有人成功地做过这种事情，我将不胜感激。

Answer 1

好的，所以我不确切地知道为什么这与RSA_sign方法有什么不同，但在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我决定阅读PHP源代码以了解它们是如何做到的。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。我希望这有助于某人。

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;

}

未在Java

1 个答案: