org.dromara.hutool.crypto.digest.otp.HOTP Maven / Gradle / Ivy
/*
* Copyright (c) 2013-2024 Hutool Team and hutool.cn
*
* 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.dromara.hutool.crypto.digest.otp;
import org.dromara.hutool.core.codec.binary.Base32;
import org.dromara.hutool.core.util.RandomUtil;
import org.dromara.hutool.crypto.digest.mac.HMac;
import org.dromara.hutool.crypto.digest.mac.HmacAlgorithm;
/**
* HMAC-based one-time passwords (HOTP) 基于HMAC算法一次性密码生成器，
* 规范见：RFC 4226.
*
* 基于事件同步，通过某一特定的事件次序及相同的种子值作为输入，通过HASH算法运算出一致的密码。
*
* 参考：https://github.com/jchambers/java-otp
*
* @author Looly
*/
public class HOTP {
/**
* 数子量级
*/
private static final int[] MOD_DIVISORS = {1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000};
/**
* 默认密码长度.
*/
public static final int DEFAULT_PASSWORD_LENGTH = 6;
/**
* 默认HMAC算法.
*/
public static final HmacAlgorithm HOTP_HMAC_ALGORITHM = HmacAlgorithm.HmacSHA1;
private final HMac mac;
private final int passwordLength;
private final int modDivisor;
private final byte[] buffer;
/**
* 构造，使用默认密码长度和默认HMAC算法(HmacSHA1)
*
* @param key 共享密码，RFC 4226要求最少128位
*/
public HOTP(final byte[] key) {
this(DEFAULT_PASSWORD_LENGTH, key);
}
/**
* 构造，使用默认HMAC算法(HmacSHA1)
*
* @param passwordLength 密码长度，可以是6,7,8
* @param key 共享密码，RFC 4226要求最少128位
*/
public HOTP(final int passwordLength, final byte[] key) {
this(passwordLength, HOTP_HMAC_ALGORITHM, key);
}
/**
* 构造
*
* @param passwordLength 密码长度，可以是6,7,8
* @param algorithm HMAC算法枚举
* @param key 共享密码，RFC 4226要求最少128位
*/
public HOTP(final int passwordLength, final HmacAlgorithm algorithm, final byte[] key) {
if(passwordLength >= MOD_DIVISORS.length){
throw new IllegalArgumentException("Password length must be < " + MOD_DIVISORS.length);
}
this.mac = new HMac(algorithm, key);
this.modDivisor = MOD_DIVISORS[passwordLength];
this.passwordLength = passwordLength;
this.buffer = new byte[8];
}
/**
* 生成一次性密码
*
* @param counter 事件计数的值，8 字节的整数，称为移动因子（moving factor），
* 可以是基于计次的动移动因子，也可以是计时移动因子
* @return 一次性密码的int值
*/
public synchronized int generate(final long counter) {
// C 的整数值需要用二进制的字符串表达，比如某个事件计数为 3，
// 则C是 "11"（此处省略了前面的二进制的数字0）
this.buffer[0] = (byte) ((counter & 0xff00000000000000L) >>> 56);
this.buffer[1] = (byte) ((counter & 0x00ff000000000000L) >>> 48);
this.buffer[2] = (byte) ((counter & 0x0000ff0000000000L) >>> 40);
this.buffer[3] = (byte) ((counter & 0x000000ff00000000L) >>> 32);
this.buffer[4] = (byte) ((counter & 0x00000000ff000000L) >>> 24);
this.buffer[5] = (byte) ((counter & 0x0000000000ff0000L) >>> 16);
this.buffer[6] = (byte) ((counter & 0x000000000000ff00L) >>> 8);
this.buffer[7] = (byte) (counter & 0x00000000000000ffL);
final byte[] digest = this.mac.digest(this.buffer);
return truncate(digest);
}
/**
* 生成共享密钥的Base32表示形式
*
* @param numBytes 将生成的种子字节数量。
* @return 共享密钥
* @since 5.7.4
*/
public static String generateSecretKey(final int numBytes) {
return Base32.encode(RandomUtil.getSHA1PRNGRandom(RandomUtil.randomBytes(256)).generateSeed(numBytes));
}
/**
* 获取密码长度，可以是6,7,8
*
* @return 密码长度，可以是6,7,8
*/
public int getPasswordLength() {
return this.passwordLength;
}
/**
* 获取HMAC算法
*
* @return HMAC算法
*/
public String getAlgorithm() {
return this.mac.getAlgorithm();
}
/**
* 截断
*
* @param digest HMAC的hash值
* @return 截断值
*/
private int truncate(final byte[] digest) {
final int offset = digest[digest.length - 1] & 0x0f;
return ((digest[offset] & 0x7f) << 24 |
(digest[offset + 1] & 0xff) << 16 |
(digest[offset + 2] & 0xff) << 8 |
(digest[offset + 3] & 0xff)) %
this.modDivisor;
}
}