Sample Java digest algorithm for encryption

This Java algorithm illustrates creating a digest token from an HTTP header.

This sample assumes:

• The web server supports Java
• The hash computation method is SHA1
• The secret key value is abc123
• The unencrypted HTTP header name is user_name

Change the Java code to use another hash computation mechanism (such as MD5), change the secret key value, or HTTP header name.

public class DigestTest
{
    private static final String MAC_ALG = "HmacSHA256";
       fKey  = {32 or more characters};
    public byte[] getDigest(String acct) {
        try {
            byte[] bkey = fKey.getBytes();
            byte[] data = acct.getBytes();
            Mac mac = null;
            try {
                mac = Mac.getInstance(MAC_ALG);
                mac.init(new SecretKeySpec(bkey, MAC_ALG));
            } catch (Exception e) {
                e.printStackTrace();
            }
            byte[] sig = mac.doFinal(data);
            String signature = new String(sig);
            System.out.println("value:" + acct);
            System.out.println("digested value:  " + signature);
            return sig;
        } catch (IllegalStateException e) {
            e.printStackTrace();
        }
        return null;
    }
    public static void main(String[] args) {
        BASE64Encoder encoder = new BASE64Encoder();
        DigestTest test = new DigestTest();
        String userName = "user_name";
        System.out.println("base 64 digest username: " + encoder.encode(test.getDigest(userName)));
    }
}