How can I calculate the SHA-256 hash of a string in Android?

Question

I\'m trying to get the SHA256 of a string in Android.

Here is the PHP code that I want to match:

echo bin2hex(mhash(MHASH_SHA256,\"asdf\"));
//output         


        

Answer 1

The PHP function bin2hex means that it takes a string of bytes and encodes it as a hexadecimal number.

In the Java code, you are trying to take a bunch of random bytes and decode them as a string using your platform's default character encoding. That isn't going to work, and if it did, it wouldn't produce the same results.

Here's a quick-and-dirty binary-to-hex conversion for Java:

static String bin2hex(byte[] data) {
    StringBuilder hex = new StringBuilder(data.length * 2);
    for (byte b : data)
        hex.append(String.format("%02x", b & 0xFF));
    return hex.toString();
}

This is quick to write, not necessarily quick to execute. If you are doing a lot of these, you should rewrite the function with a faster implementation.