Get Hash of SHA1

SHA1.java

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

public class SHA1 {

    private MessageDigest md;
    private byte[] buffer, digest;
    private String hash = "";

    public String getHash(String message) throws NoSuchAlgorithmException {
        buffer = message.getBytes();
        md = MessageDigest.getInstance("SHA1");
        md.update(buffer);
        digest = md.digest();

        for (byte aux : digest) {
            int b = aux & 0xff;
            if (Integer.toHexString(b).length() == 1) {
                hash += "0";
            }
            hash += Integer.toHexString(b);
        }
        return hash;
    }
}