AeSimpleSHA256.java

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package Lib;

import java.io.UnsupportedEncodingException; 
import java.math.BigInteger;
import java.security.MessageDigest; 
import java.security.NoSuchAlgorithmException; 
import java.security.spec.InvalidKeySpecException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;

/**
 *
 * @author Tom
 */
public class AeSimpleSHA256 {
    
     /**
     * Converts a byte array into a hexadecimal string.
     *
     * @param   array       the byte array to convert
     * @return              a length*2 character string encoding the byte array
     */
    public static String toHex(byte[] array)
    {
        BigInteger bi = new BigInteger(1, array);
        String hex = bi.toString(16);
        int paddingLength = (array.length * 2) - hex.length();
        if(paddingLength > 0)
            return String.format("%0" + paddingLength + "d", 0) + hex;
        else
            return hex;
    }
    
    /**
     * Converts a string of hexadecimal characters into a byte array.
     *
     * @param   hex         the hex string
     * @return              the hex string decoded into a byte array
     */
    public static byte[] fromHex(String hex)
    {
        byte[] binary = new byte[hex.length() / 2];
        for(int i = 0; i < binary.length; i++)
        {
            binary[i] = (byte)Integer.parseInt(hex.substring(2*i, 2*i+2), 16);
        }
        return binary;
    }
    
    public static String getHash(String password, byte[] salt)
            throws NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeySpecException{
        byte[] hash = pbkdf2(password.toCharArray(), salt, 1000, 32);
        return toHex(hash);
    }    
    
    /**
     *  Computes the PBKDF2 hash of a password.
     *
     * @param   password    the password to hash.
     * @param   salt        the salt
     * @param   iterations  the iteration count (slowness factor)
     * @param   bytes       the length of the hash to compute in bytes
     * @return              the PBDKF2 hash of the password
     */
    public static byte[] pbkdf2(char[] password, byte[] salt, int iterations, int bytes)
        throws NoSuchAlgorithmException, InvalidKeySpecException
    {
        PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * 8);
        SecretKeyFactory skf = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
        return skf.generateSecret(spec).getEncoded();
    }
    
    public static String SHA256 (String text)
            throws NoSuchAlgorithmException, UnsupportedEncodingException{
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(text.getBytes("iso-8859-1"), 0, text.length());
        byte[] sha256Hash = md.digest();
        return toHex(sha256Hash);
    }
}