com.hazelcast.internal.util.UuidUtil Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2021, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.internal.util;
import java.security.SecureRandom;
import java.util.Random;
import java.util.UUID;
/**
* Util class to generate type 4 (pseudo randomly generated) {@link UUID}.
*
* Creates {@link UUID} of different quality of randomness,
* which are based on cryptographically weak {@link Random}
* and strong {@link SecureRandom} pseudo random number generators.
*/
public final class UuidUtil {
/**
* The nil UUID is special form of UUID that is specified to have all
* 128 bits set to zero as described in the RFC 4122.
*/
public static final UUID NIL_UUID = new UUID(0, 0);
private UuidUtil() {
}
/**
* Static factory to retrieve a type 4 (pseudo randomly generated) UUID based string.
*
* The {@code UUID} string is generated using a cryptographically weak pseudo random number generator.
*
* @return A randomly generated {@code UUID} base string
*/
public static String newUnsecureUuidString() {
return newUnsecureUUID().toString();
}
/**
* Static factory to retrieve a type 4 (pseudo randomly generated) UUID based string.
*
* The {@code UUID} string is generated using a cryptographically strong pseudo random number generator.
*
* @return A randomly generated {@code UUID} base string
*/
public static String newSecureUuidString() {
return newSecureUUID().toString();
}
/**
* Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
*
* The {@code UUID} is generated using a cryptographically weak pseudo random number generator.
*
* @return A randomly generated {@code UUID}
*/
public static UUID newUnsecureUUID() {
return getUUID(ThreadLocalRandomProvider.get());
}
/**
* Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
*
* The {@code UUID} is generated using a cryptographically strong pseudo random number generator.
*
* @return A randomly generated {@code UUID}
*/
public static UUID newSecureUUID() {
return getUUID(ThreadLocalRandomProvider.getSecure());
}
@SuppressWarnings("checkstyle:magicnumber")
private static UUID getUUID(Random random) {
byte[] data = new byte[16];
random.nextBytes(data);
// clear version
data[6] &= 0x0f;
// set to version 4
data[6] |= 0x40;
// clear variant
data[8] &= 0x3f;
// set to IETF variant
data[8] |= 0x80;
long mostSigBits = 0;
long leastSigBits = 0;
assert data.length == 16 : "data must be 16 bytes in length";
for (int i = 0; i < 8; i++) {
mostSigBits = (mostSigBits << 8) | (data[i] & 0xff);
}
for (int i = 8; i < 16; i++) {
leastSigBits = (leastSigBits << 8) | (data[i] & 0xff);
}
return new UUID(mostSigBits, leastSigBits);
}
}