io.jsonwebtoken.impl.crypto.MacProvider Maven / Gradle / Ivy
/*
* Copyright (C) 2014 jsonwebtoken.io
*
* 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 io.jsonwebtoken.impl.crypto;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.lang.Assert;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.SecureRandom;
public abstract class MacProvider extends SignatureProvider {
protected MacProvider(SignatureAlgorithm alg, Key key) {
super(alg, key);
Assert.isTrue(alg.isHmac(), "SignatureAlgorithm must be a HMAC SHA algorithm.");
}
/**
* Generates a new secure-random 512 bit secret key suitable for creating and verifying HMAC signatures. This is a
* convenience method that immediately delegates to {@link #generateKey(SignatureAlgorithm)} using {@link
* SignatureAlgorithm#HS512} as the method argument.
*
* @return a new secure-random 512 bit secret key suitable for creating and verifying HMAC signatures.
* @see #generateKey(SignatureAlgorithm)
* @see #generateKey(SignatureAlgorithm, SecureRandom)
* @since 0.5
*/
public static SecretKey generateKey() {
return generateKey(SignatureAlgorithm.HS512);
}
/**
* Generates a new secure-random secret key of a length suitable for creating and verifying HMAC signatures
* according to the specified {@code SignatureAlgorithm} using JJWT's default {@link
* SignatureProvider#DEFAULT_SECURE_RANDOM SecureRandom instance}. This is a convenience method that immediately
* delegates to {@link #generateKey(SignatureAlgorithm, SecureRandom)}.
*
* @param alg the desired signature algorithm
* @return a new secure-random secret key of a length suitable for creating and verifying HMAC signatures according
* to the specified {@code SignatureAlgorithm} using JJWT's default {@link SignatureProvider#DEFAULT_SECURE_RANDOM
* SecureRandom instance}.
* @see #generateKey()
* @see #generateKey(SignatureAlgorithm, SecureRandom)
* @since 0.5
*/
public static SecretKey generateKey(SignatureAlgorithm alg) {
return generateKey(alg, SignatureProvider.DEFAULT_SECURE_RANDOM);
}
/**
* Generates a new secure-random secret key of a length suitable for creating and verifying HMAC signatures
* according to the specified {@code SignatureAlgorithm} using the specified SecureRandom number generator. This
* implementation returns secure-random key sizes as follows:
*
* Signature Algorithm Generated Key Size
* HS256 256 bits (32 bytes) HS384 384 bits (48 bytes)
* HS512 256 bits (64 bytes)
*
* @param alg the signature algorithm that will be used with the generated key
* @param random the secure random number generator used during key generation
* @return a new secure-random secret key of a length suitable for creating and verifying HMAC signatures according
* to the specified {@code SignatureAlgorithm} using the specified SecureRandom number generator.
* @see #generateKey()
* @see #generateKey(SignatureAlgorithm)
* @since 0.5
*/
public static SecretKey generateKey(SignatureAlgorithm alg, SecureRandom random) {
Assert.isTrue(alg.isHmac(), "SignatureAlgorithm argument must represent an HMAC algorithm.");
byte[] bytes;
switch (alg) {
case HS256:
bytes = new byte[32];
break;
case HS384:
bytes = new byte[48];
break;
default:
bytes = new byte[64];
}
random.nextBytes(bytes);
return new SecretKeySpec(bytes, alg.getJcaName());
}
}