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package org.bouncycastle.crypto.tls;
import java.math.BigInteger;
import org.bouncycastle.crypto.Mac;
import org.bouncycastle.crypto.agreement.srp.SRP6VerifierGenerator;
import org.bouncycastle.crypto.macs.HMac;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.SRP6GroupParameters;
import org.bouncycastle.util.Strings;
/**
* An implementation of {@link TlsSRPIdentityManager} that simulates the existence of "unknown" identities
* to obscure the fact that there is no verifier for them.
*/
public class SimulatedTlsSRPIdentityManager
implements TlsSRPIdentityManager
{
private static final byte[] PREFIX_PASSWORD = Strings.toByteArray("password");
private static final byte[] PREFIX_SALT = Strings.toByteArray("salt");
/**
* Create a {@link SimulatedTlsSRPIdentityManager} that implements the algorithm from RFC 5054 2.5.1.3
*
* @param group the {@link SRP6GroupParameters} defining the group that SRP is operating in
* @param seedKey the secret "seed key" referred to in RFC 5054 2.5.1.3
* @return an instance of {@link SimulatedTlsSRPIdentityManager}
*/
public static SimulatedTlsSRPIdentityManager getRFC5054Default(SRP6GroupParameters group, byte[] seedKey)
{
SRP6VerifierGenerator verifierGenerator = new SRP6VerifierGenerator();
verifierGenerator.init(group, TlsUtils.createHash(HashAlgorithm.sha1));
HMac mac = new HMac(TlsUtils.createHash(HashAlgorithm.sha1));
mac.init(new KeyParameter(seedKey));
return new SimulatedTlsSRPIdentityManager(group, verifierGenerator, mac);
}
protected SRP6GroupParameters group;
protected SRP6VerifierGenerator verifierGenerator;
protected Mac mac;
public SimulatedTlsSRPIdentityManager(SRP6GroupParameters group, SRP6VerifierGenerator verifierGenerator, Mac mac)
{
this.group = group;
this.verifierGenerator = verifierGenerator;
this.mac = mac;
}
public TlsSRPLoginParameters getLoginParameters(byte[] identity)
{
mac.update(PREFIX_SALT, 0, PREFIX_SALT.length);
mac.update(identity, 0, identity.length);
byte[] salt = new byte[mac.getMacSize()];
mac.doFinal(salt, 0);
mac.update(PREFIX_PASSWORD, 0, PREFIX_PASSWORD.length);
mac.update(identity, 0, identity.length);
byte[] password = new byte[mac.getMacSize()];
mac.doFinal(password, 0);
BigInteger verifier = verifierGenerator.generateVerifier(salt, identity, password);
return new TlsSRPLoginParameters(group, verifier, salt);
}
}
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