SslUtils.java

package com.undatech.opaque.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class SslUtils {

    public static String signature(String algorithm, byte[] data) throws NoSuchAlgorithmException {
        MessageDigest digest =  MessageDigest.getInstance(algorithm);
        return SslUtils.toHexString(digest.digest(data)).trim();
    }
    
    /**
     * Converts a given sequence of bytes to a human-readable colon-separated Hex format. 
     * @param bytes
     * @return
     */
    public static String toHexString(byte[] bytes) {
        char[] hexArray = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
        char[] hexChars = new char[bytes.length * 3];
        int v, j;
        for ( j = 0; j < bytes.length - 1; j++ ) {
            v = bytes[j] & 0xFF;
            hexChars[j*3] = hexArray[v/16];
            hexChars[j*3 + 1] = hexArray[v%16];
            hexChars[j*3 + 2] = ":".charAt(0);
        }
        v = bytes[j] & 0xFF;
        hexChars[j*3] = hexArray[v/16];
        hexChars[j*3 + 1] = hexArray[v%16];
        return new String(hexChars);
    }

}