com.theicenet.cryptography.keyagreement.pake.srp.v6a.RFC5054SRP6ClientService Maven / Gradle / Ivy
/*
* Copyright 2019-2021 the original author or authors.
*
* 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
*
* https://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.theicenet.cryptography.keyagreement.pake.srp.v6a;
import static com.theicenet.cryptography.util.ByteArraysUtil.toBigInteger;
import static com.theicenet.cryptography.util.ByteArraysUtil.toUnsignedByteArray;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6ClientUtil.computeA;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6ClientUtil.computeX;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6CommonUtil.computeK;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6CommonUtil.computeM2;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6CommonUtil.computeU;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6CommonUtil.generatePrivateValue;
import static com.theicenet.cryptography.keyagreement.pake.srp.v6a.SRP6CommonUtil.isValidPublicValue;
import static com.theicenet.cryptography.util.SecureEqualUtil.areEqual;
import com.theicenet.cryptography.digest.DigestAlgorithm;
import com.theicenet.cryptography.digest.DigestService;
import com.theicenet.cryptography.digest.JCADigestService;
import com.theicenet.cryptography.keyagreement.SRP6ClientService;
import com.theicenet.cryptography.random.SecureRandomDataService;
import java.math.BigInteger;
import org.apache.commons.lang.Validate;
/**
* Implementation for SRP6 v6a 'client' service according to Specification RFC 5054.
*
* @see Specification: RFC 5054
* @see Specification: RFC 2945
* @see Secure Remote Password protocol
*
* @implNote This implementation is unconditionally thread-safe as required by the API interface.
*
* @author Juan Fidalgo
* @since 1.1.0
*/
public class RFC5054SRP6ClientService implements SRP6ClientService {
private final SRP6StandardGroup standardGroup;
private final DigestService digestService;
private final SecureRandomDataService secureRandomDataService;
/**
* @param standardGroup N,g standard group to use for this SRP6 RFC 5054 specification instance
* @param digestAlgorithm hashing algorithm to use for this SRP6 RFC 5054 specification instance
* @param secureRandomDataService service to generate secure random data
*/
public RFC5054SRP6ClientService(
SRP6StandardGroup standardGroup,
DigestAlgorithm digestAlgorithm,
SecureRandomDataService secureRandomDataService) {
Validate.notNull(standardGroup);
Validate.notNull(digestAlgorithm);
Validate.notNull(secureRandomDataService);
this.standardGroup = standardGroup;
this.digestService = new JCADigestService(digestAlgorithm);
this.secureRandomDataService = secureRandomDataService;
}
/**
* Generates a random SRP client's private value 'a' which is, according to the specification,
* of at least 256 bits in length.
*
* Based on the generated client's private value 'a' it computes the client's public value 'A'
* according to the standard routine:
*
* A = (g^a) mod N
*
* @implNote This implementation ensures that the produced 'A' satisfies that
*
* A mod N != 0
*
* as required by the API interface.
*/
@Override
public SRP6ClientValuesA computeValuesA() {
BigInteger clientPrivateValueA;
BigInteger clientPublicValueA;
do {
// Generate client's private value a
clientPrivateValueA =
generatePrivateValue(
standardGroup.getN(),
secureRandomDataService);
// Generate client's public value A
clientPublicValueA =
computeA(
standardGroup.getN(),
standardGroup.getG(),
clientPrivateValueA);
} while (!isValidPublicValue(standardGroup.getN(), clientPublicValueA)); // loop till the client's public value A is valid
return
new SRP6ClientValuesA(
toUnsignedByteArray(clientPrivateValueA),
toUnsignedByteArray(clientPublicValueA));
}
/**
* Computes the client's pre-master secret 'S' according to the standard routine:
*
* S = ((B - (k * (g^x))) ^ (a + (u * x))) mod N
*/
@Override
public byte[] computeS(
byte[] salt,
byte[] identity,
byte[] password,
byte[] clientPrivateValueA,
byte[] clientPublicValueA,
byte[] serverPublicValueB) {
Validate.notNull(salt);
Validate.notNull(identity);
Validate.notNull(password);
Validate.notNull(clientPrivateValueA);
Validate.notNull(clientPublicValueA);
Validate.notNull(serverPublicValueB);
final BigInteger k = computeK(digestService, standardGroup.getN(), standardGroup.getG());
final BigInteger x = computeX(digestService, salt, identity, password);
final BigInteger u =
computeU(
digestService,
standardGroup.getN(),
toBigInteger(clientPublicValueA),
toBigInteger(serverPublicValueB));
return
toUnsignedByteArray(
SRP6ClientUtil.computeS(
standardGroup.getN(),
standardGroup.getG(),
k,
x,
u,
toBigInteger(clientPrivateValueA),
toBigInteger(serverPublicValueB)));
}
/**
* Computes the client's evidence message 'M1' according to the standard routine:
*
* M1 = H( A | B | S )
*/
@Override
public byte[] computeM1(byte[] clientPublicValueA, byte[] serverPublicValueB, byte[] s) {
Validate.notNull(clientPublicValueA);
Validate.notNull(serverPublicValueB);
Validate.notNull(s);
return
toUnsignedByteArray(
SRP6CommonUtil.computeM1(
digestService,
standardGroup.getN(),
toBigInteger(clientPublicValueA),
toBigInteger(serverPublicValueB),
toBigInteger(s)));
}
/**
* Computes the server's evidence message 'M2' according to the standard routine:
*
* M2 = H( A | M1 | S )
*
* and compares the resulting value with what is passed in `receivedM2` to determine if the
* received server's evidence message 'M2' is valid or not
*/
@Override
public boolean isValidReceivedM2(
byte[] clientPublicValueA,
byte[] s,
byte[] m1,
byte[] receivedM2) {
Validate.notNull(clientPublicValueA);
Validate.notNull(s);
Validate.notNull(m1);
Validate.notNull(receivedM2);
final BigInteger m2 =
computeM2(
digestService,
standardGroup.getN(),
toBigInteger(clientPublicValueA),
toBigInteger(m1),
toBigInteger(s));
return areEqual(toUnsignedByteArray(m2), receivedM2);
}
/**
* Computes the common session 'Key' according to the standard routine:
*
* Key = H(S)
*/
@Override
public byte[] computeSessionKey(byte[] s) {
Validate.notNull(s);
return
toUnsignedByteArray(
SRP6CommonUtil.computeSessionKey(
digestService,
standardGroup.getN(),
toBigInteger(s)));
}
}
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