Java and JavaScript same sha256 hex

Question

To get a Java SHA256 hash I use the following method:

public String getSha256(String text, String encoding){
    String sha = "";
    try {
        MessageDigest md = MessageDigest.getInstance("SHA-256");

        md.update(text.getBytes(encoding));
        byte[] digest = md.digest();
        sha = new String(digest);
        sha = sha.replace("\n", "");
    } catch (NoSuchAlgorithmException | UnsupportedEncodingException ex) {
        Logger.getLogger(Utils.class.getName()).log(Level.SEVERE, null, ex);
    }
    return sha;
}

Like so:

String testValue = getSha256("test", "UTF-8");

Then to get the HEX value out of it I do the following:

public String getHexFromString(String text){
    String hex = "";
    try {
        byte[] myBytes = text.getBytes("UTF-8");
        hex = DatatypeConverter.printHexBinary(myBytes);
    } catch (UnsupportedEncodingException ex) {
        Logger.getLogger(Utils.class.getName()).log(Level.SEVERE, null, ex);
    }
    return hex;
}

System.out.print(getHexFromString(testValue));

The result of this is:

C5B8E280A0C390EFBFBDCB864C7D65C5A12FC3AAC2A0C3855AC39015C2A3C2BF4F1B2B0BE2809A2CC3915D6C15C2B0C3B008

In javascript I do the following (using this library):

var hash = sjcl.hash.sha256.hash("test");
console.log(sjcl.codec.hex.fromBits(hash));

And the result is:

9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08

How can I get same hex in Java and Javascript?

What am I doing wrong, is it the Java or Javascript code?

sha = new String(digest); - don't do this. The digest is arbitrary binary data. You should convert digest to hex, rather than converting it into a string and then calling your getHexFromString code. That's almost certainly part of the problem. — Jon Skeet
– Jon Skeet, Commented Mar 12, 2017 at 22:46
@JonSkeet thanks, this solved the issue :) ... also thanks for answering my other questions longer ago, somehow you are the right guy at the right place, ill remember that :P — Alpha2k
– Alpha2k, Commented Mar 13, 2017 at 0:30

Alpha2k · Accepted Answer · 2017-03-13 00:28:04Z

2

@JonSkeet was right, changed the method, it now looks like this:

public String getSha256Hex(String text, String encoding){
    String shaHex = "";
    try {
        MessageDigest md = MessageDigest.getInstance("SHA-256");

        md.update(text.getBytes(encoding));
        byte[] digest = md.digest();

        shaHex = DatatypeConverter.printHexBinary(digest);
    } catch (NoSuchAlgorithmException | UnsupportedEncodingException ex) {
        Logger.getLogger(Utils.class.getName()).log(Level.SEVERE, null, ex);
    }
    return shaHex;
}

And the result is:

9F86D081884C7D659A2FEAA0C55AD015A3BF4F1B2B0B822CD15D6C15B0F00A08

The only difference is that the Java hex is upper case, but thats a minor thing to solve.

answered Mar 13, 2017 at 0:28

Alpha2k

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