/*
* ModeShape (http://www.modeshape.org)
*
* 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.modeshape.common.text;
import java.security.NoSuchAlgorithmException;
import org.modeshape.common.util.Base64;
import org.modeshape.common.util.CheckArg;
import org.modeshape.common.util.SecureHash;
import org.modeshape.common.util.SecureHash.Algorithm;
/**
* A text encoder that performs a secure hash of the input text and returns that hash as the encoded text. This encoder can be
* configured to use different secure hash algorithms and to return a fixed number of characters from the hash.
*/
public class SecureHashTextEncoder implements TextEncoder {
private final Algorithm algorithm;
private final int maxLength;
/**
* Create an encoder that uses the supplied algorithm and returns only the supplied number of characters in the hash.
*
* @param algorithm the algorithm that should be used
* @throws IllegalArgumentException if the algorithm is null
*/
public SecureHashTextEncoder( Algorithm algorithm ) {
this(algorithm, Integer.MAX_VALUE);
}
/**
* Create an encoder that uses the supplied algorithm and returns only the supplied number of characters in the hash.
*
* @param algorithm the algorithm that should be used
* @param maxLength the maximumLength, or a non-positive number (or {@link Integer#MAX_VALUE}) if the full hash should be used
* @throws IllegalArgumentException if the algorithm is null
*/
public SecureHashTextEncoder( Algorithm algorithm,
int maxLength ) {
CheckArg.isNotNull(algorithm, "algorithm");
this.algorithm = algorithm;
this.maxLength = maxLength < 1 ? Integer.MAX_VALUE : maxLength;
}
/**
* Get the maximum length of the encoded string, or {@link Integer#MAX_VALUE} if there is no maximum.
*
* @return the maximum encoded string length; always positive
*/
public int getMaxLength() {
return maxLength;
}
/**
* Return the secure hash algorithm used by this encoder.
*
* @return the algorithm; never null
*/
public Algorithm getAlgorithm() {
return algorithm;
}
/**
* {@inheritDoc}
*
* @see org.modeshape.common.text.TextEncoder#encode(java.lang.String)
*/
@Override
public String encode( String text ) {
try {
byte[] hash = SecureHash.getHash(algorithm, text.getBytes());
String result = Base64.encodeBytes(hash);
return result.length() < maxLength ? result : result.substring(0, maxLength);
} catch (NoSuchAlgorithmException e) {
return text;
}
}
}