net.siisise.security.HOTP Maven / Gradle / Ivy
/*
* Copyright 2023 okome.
*
* 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 net.siisise.security;
import java.math.BigInteger;
import net.siisise.security.digest.SHA1;
import net.siisise.security.mac.HMAC;
/**
* RFC 4226 HOTP
*/
public class HOTP implements OTP {
HMAC hmac;
byte[] K;
int Digit = 6;
/**
* Section 5.2.
* @param key K
* @param counter C
*/
int hotp(byte[] key, byte[] counter) {
hmac = new HMAC(new SHA1(), key);
byte[] hs = hmac.doFinal(counter);
byte[] Sbits = DT(hs);
int Snum = StToNum(Sbits); // Convert S to a number in
// 0...2^{31}-1
return Snum % (10^Digit);
// hs = Truncate(hs);
}
byte[] DT(byte[] hs) {
throw new UnsupportedOperationException();
}
int StToNum(byte[] sbits) {
BigInteger num = new BigInteger(sbits);
return num.intValue();
}
/**
* Section 5.3.
* @param hs
* @return
*/
byte[] Truncate(byte[] hs) {
throw new UnsupportedOperationException();
}
}