Ierative Java SHA-1 versus Python solution

I have a specific problem with hashing algorithms in Java. I have 2 clients, one is working in python and the other is working in Java (I know I could solve everything using only python, but now I almost need to use java).

Clients should compare pasted passwords in the same way (i.e.: if the PIN generates a hash on java clients , then the same hash should be generated by the python client.

I am reading here: Iterative hashing returns different values ​​in Python and Java

And studied the official docs here: https://docs.oracle.com/javase/7/docs/api/java/security/MessageDigest.html

And it turned out that python allows seamless iterative coding, while java does not. I tried to solve the problem using the .clone () method as follows (java code):

        // creation of SHA-1 instance:
        MessageDigest message = MessageDigest.getInstance("SHA-1");
        // construction of the string to hash:
        String secretMessage = "0" + myPassWord + mySalt;
        // updating the instance:
        message.update(secretMessage.getBytes());
        // cloning the instance:
        MessageDigest messageClone = (MessageDigest) message.clone();
        // digesting the clone: the result is of type byte[]:
        byteResult = messageClone.digest();
        // construction of the previousHash: this will be used in the 
        // next run of SHA-1 hashing. Python runs everything in lowercase.
        // the hash is rendered as HEX characters String:
        prevHash = (DatatypeConverter.printHexBinary(byteResult)).toLowerCase();
        secretMessage = prevHash + "1" + myPassWord + mySalt;
        message.update(secretMessage.getBytes());
        // compute the final digest:
        byteResult = message.digest();
        // print it:
        System.out.println(DatatypeConverter.printHexBinary(byteResult));

      

        
        
        
      

    

Now, running System.out.println on the first iteration (index "0"), the hashes match.

Unfortunately, something goes wrong on the next index, and I can't, for love's sake, understand what it is. I suspect it has something to do with how python converts strings and inserts it into the secretMessage variable.

For your information, here is the code in python:

digest2 = ""
for i in range (0, 2):
    digest2 = sha1(digest2 + str(i) + password_to_hash + salt).hexdigest()
    print digest2