Commonly used hash functions

HashUtils.java

package com.calciumion.util;

import android.util.Base64;

import java.security.MessageDigest;
import java.security.SignatureException;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

/**
 * Commonly used hash functions
 * 
 * @author bowang
 * 
 */
public final class HashUtils {

	private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

	private HashUtils() {
		throw new AssertionError();
	}

	static final String hexString(byte[] raw) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < raw.length; i++) {
			sb.append(Integer.toString((raw[i] & 0xff) + 0x100, 16)
					.substring(1));
		}
		return sb.toString();
	}

	public static final String md5(String raw) {
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(raw.getBytes());
			return hexString(md.digest());
		} catch (Exception e) {
		}
		return null;
	}

	public static final String sha1(String raw) {
		return sha1(raw.getBytes());
	}

	public static final String sha1(byte[] bytes) {
		try {
			MessageDigest md = MessageDigest.getInstance("SHA1");
			md.update(bytes);
			return hexString(md.digest());
		} catch (Exception e) {
		}
		return null;
	}

	public static final String sha1Base64(byte[] bytes) {
		try {
			MessageDigest md = MessageDigest.getInstance("SHA1");
			md.update(bytes);
			return Base64.encodeToString(md.digest(), Base64.DEFAULT);
		} catch (Exception e) {
		}
		return null;
	}

	/**
	 * Computes RFC 2104-compliant HMAC signature.
	 * 
	 * @param raw
	 *            The data to be signed.
	 * @param key
	 *            The signing key.
	 * @return The Base64-encoded RFC 2104-compliant HMAC signature.
	 * @throws java.security.SignatureException
	 *             when signature generation fails
	 */
	public static String hmacsha1(String raw, String key)
			throws SignatureException {
		try {
			// get an hmac_sha1 key from the raw key bytes
			SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(),
					HMAC_SHA1_ALGORITHM);

			// get an hmac_sha1 Mac instance and initialize with the signing key
			Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
			mac.init(signingKey);

			// compute the hmac on input data bytes
			byte[] rawHmac = mac.doFinal(raw.getBytes());
			return hexString(rawHmac);
		} catch (Exception e) {
			throw new SignatureException("Failed to generate HMAC : "
					+ e.getMessage());
		}

	}

}