/**
* JBoss, Home of Professional Open Source
* Copyright Red Hat, Inc., and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.aerogear.security.otp.api;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.ByteBuffer;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
public class Hmac {
public static final String ALGORITHM = "RAW";
private final Hash hash;
private final byte[] secret;
private final long currentInterval;
public Hmac(Hash hash, byte[] secret, long currentInterval) {
this.hash = hash;
this.secret = secret;
this.currentInterval = currentInterval;
}
public byte[] digest() throws NoSuchAlgorithmException, InvalidKeyException {
byte[] challenge = ByteBuffer.allocate(8).putLong(currentInterval).array();
Mac mac = Mac.getInstance(hash.toString());
SecretKeySpec macKey = new SecretKeySpec(secret, ALGORITHM);
mac.init(macKey);
return mac.doFinal(challenge);
}
}