org.jose4j.jwe.CipherStrengthSupport Maven / Gradle / Ivy
/*
* Copyright 2012-2017 Brian Campbell
*
* 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.jose4j.jwe;
import org.jose4j.lang.ByteUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.crypto.Cipher;
import java.security.NoSuchAlgorithmException;
/**
*/
public class CipherStrengthSupport
{
private static final Logger log = LoggerFactory.getLogger(CipherStrengthSupport.class);
public static boolean isAvailable(String algorithm, int keyByteLength)
{
boolean isAvailable;
int bitKeyLength = ByteUtil.bitLength(keyByteLength);
try
{
int maxAllowedKeyLength = Cipher.getMaxAllowedKeyLength(algorithm);
isAvailable = (bitKeyLength <= maxAllowedKeyLength);
if (!isAvailable)
{
log.debug("max allowed key length for {} is {}", algorithm, maxAllowedKeyLength);
}
}
catch (NoSuchAlgorithmException e)
{
log.debug("Unknown/unsupported algorithm, {} {}", algorithm, e);
isAvailable = false;
}
return isAvailable;
}
}