Der Lanwirt

public static final String Sha1(final String s) {
	try
	{
		MessageDigest digest = java.security.MessageDigest
				.getInstance("SHA-1");
		digest.update(s.getBytes());
		byte messageDigest[] = digest.digest();
		StringBuffer hexString = new StringBuffer();
		for (int i = 0; i < messageDigest.length; i++)
		{
			String h = Integer.toHexString(0xFF & messageDigest[i]);
			while (h.length() < 2)
			h = "0" + h;
			hexString.append(h);
		}
		return hexString.toString();
	}
	catch (NoSuchAlgorithmException e)
	{
		e.printStackTrace();
	}
	return "";
}

Quelle: http://www.kospol.gr/204/create-md5-hashes-in-android/