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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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.elasticsearch.common.hash;
import org.elasticsearch.ElasticsearchException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Objects;
public class MessageDigests {
private static ThreadLocal createThreadLocalMessageDigest(final String digest) {
return new ThreadLocal() {
@Override
protected MessageDigest initialValue() {
try {
return MessageDigest.getInstance(digest);
} catch (NoSuchAlgorithmException e) {
throw new ElasticsearchException("unexpected exception creating MessageDigest instance for [" + digest + "]", e);
}
}
};
}
private static final ThreadLocal MD5_DIGEST = createThreadLocalMessageDigest("MD5");
private static final ThreadLocal SHA_1_DIGEST = createThreadLocalMessageDigest("SHA-1");
private static final ThreadLocal SHA_256_DIGEST = createThreadLocalMessageDigest("SHA-256");
public static MessageDigest md5() {
return get(MD5_DIGEST);
}
public static MessageDigest sha1() {
return get(SHA_1_DIGEST);
}
public static MessageDigest sha256() {
return get(SHA_256_DIGEST);
}
private static MessageDigest get(ThreadLocal messageDigest) {
MessageDigest instance = messageDigest.get();
instance.reset();
return instance;
}
private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();
public static String toHexString(byte[] bytes) {
Objects.requireNonNull(bytes);
StringBuilder sb = new StringBuilder(2 * bytes.length);
for (int i = 0; i < bytes.length; i++) {
byte b = bytes[i];
sb.append(HEX_DIGITS[b >> 4 & 0xf]).append(HEX_DIGITS[b & 0xf]);
}
return sb.toString();
}
}