name.martingeisse.common.util.HmacUtil.java Source code

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Here is the source code for name.martingeisse.common.util.HmacUtil.java

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/**
 * Copyright (c) 2010 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.common.util;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;

/**
 * Utility methods to deal with HMACs.
 */
public class HmacUtil {

    /**
     * Use this constant for the "algorithm" parameter for SHA256.
     */
    public static final String ALGORITHM_SHA256 = "HmacSHA256";

    /**
     * Base function to generate a HMAC.
     * 
     * @param payload the payload data
     * @param secret the secret to sign the HMAC
     * @param algorithm the HMAC algorithm to use
     * @return the HMAC
     */
    public static byte[] generateHmac(byte[] payload, byte[] secret, String algorithm) {
        try {
            final Mac mac = Mac.getInstance(algorithm);
            mac.init(new SecretKeySpec(secret, algorithm));
            return mac.doFinal(payload);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } catch (InvalidKeyException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Generates a HMAC, assuming UTF-8 encoding for all strings.
     * 
     * @param payload the payload data
     * @param secret the secret to sign the HMAC
     * @param algorithm the HMAC algorithm to use
     * @return the HMAC
     */
    public static byte[] generateHmac(String payload, String secret, String algorithm) {
        Charset utf8 = StandardCharsets.UTF_8;
        return generateHmac(payload.getBytes(utf8), secret.getBytes(utf8), algorithm);
    }

    /**
     * Generates a HMAC, assuming UTF-8 encoding for all strings, and base64-encodes
     * the result.
     * 
     * @param payload the payload data
     * @param secret the secret to sign the HMAC
     * @param algorithm the HMAC algorithm to use
     * @return the HMAC, base64 encoded
     */
    public static String generateHmacBase64(String payload, String secret, String algorithm) {
        return Base64.encodeBase64String(generateHmac(payload, secret, algorithm));
    }

}