在 C++ 和 JAVA 中发现相同字符串的 SHA-1 不同

Question

SHA-1 for the same string is different is Java and C++

String to hash - 38902566

SHA-1 in java - 6ffc3d4038943971cd91db0cf0f3de8ecf1b2853 (confirmed online sha1 tool produces same)

SHA-1 in C++ - 093288D2933CE7D55295450EBFE711F3E1AE3BF2

Java implementation:

  MessageDigest md = MessageDigest.getInstance("SHA-1");
  byte[] messageDigest = md.digest(customerId.getBytes());
  BigInteger no = new BigInteger(1, messageDigest);

  String hashtext = no.toString(16);

  while (hashtext.length() < 32) {
    hashtext = "0" + hashtext;
  }
  return hashtext;

C++ implementation

int hash_SHA1(const char* cid, int len, char* digest)
{
    /* Creating Id Digest. */
    int rc = 0, i;
    unsigned char idDgst[21] = { '\0' };
    char buffer[3] = { '\0' };

    rc = SHA1(cid, len, idDgst) == NULL ? -1 : 0;
    for(i = 0; !rc && (i < sizeof(idDgst)-1); i++)
    {
        sprintf(buffer, "%02X", idDgst[i]);
        strncat(digest, buffer, 3);
    }
    return rc == 0;
}

C++ code was shared with me to implement in Java. What am I doing wrong here?

Answer 1

There was extra char getting appended to the input string from where the function was called in the C code. Giving the right input gave the exact same result. Thanks @Topaco, for validating the code.

Answer 2

Java can use 16-bit for each character in String. C++ - not.