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using System;
using System.IO;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Tls.Crypto;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Tls
{
/// <summary>An implementation of <see cref="TlsSrpIdentityManager"/> that simulates the existence of "unknown"
/// identities to obscure the fact that there is no verifier for them.</summary>
public class SimulatedTlsSrpIdentityManager
: TlsSrpIdentityManager
{
private static readonly byte[] PrefixPassword = Strings.ToByteArray("password");
private static readonly byte[] PrefixSalt = Strings.ToByteArray("salt");
/// <summary>Create a <see cref="SimulatedTlsSrpIdentityManager"/> that implements the algorithm from RFC 5054
/// 2.5.1.3.</summary>
/// <param name="crypto"><see cref="TlsCrypto"/></param>
/// <param name="group">the <see cref="Srp6Group"/> defining the group that SRP is operating in.</param>
/// <param name="seedKey">the secret "seed key" referred to in RFC 5054 2.5.1.3.</param>
/// <returns>an instance of <see cref="SimulatedTlsSrpIdentityManager"/>.</returns>
/// <exception cref="IOException"/>
public static SimulatedTlsSrpIdentityManager GetRfc5054Default(TlsCrypto crypto, Srp6Group group, byte[] seedKey)
{
TlsMac mac = crypto.CreateHmac(MacAlgorithm.hmac_sha1);
mac.SetKey(seedKey, 0, seedKey.Length);
TlsSrpConfig srpConfig = new TlsSrpConfig();
srpConfig.SetExplicitNG(new BigInteger[]{ group.N, group.G });
return new SimulatedTlsSrpIdentityManager(group, crypto.CreateSrp6VerifierGenerator(srpConfig), mac);
}
protected readonly Srp6Group m_group;
protected readonly TlsSrp6VerifierGenerator m_verifierGenerator;
protected readonly TlsMac m_mac;
public SimulatedTlsSrpIdentityManager(Srp6Group group, TlsSrp6VerifierGenerator verifierGenerator, TlsMac mac)
{
this.m_group = group;
this.m_verifierGenerator = verifierGenerator;
this.m_mac = mac;
}
public virtual TlsSrpLoginParameters GetLoginParameters(byte[] identity)
{
m_mac.Update(PrefixSalt, 0, PrefixSalt.Length);
m_mac.Update(identity, 0, identity.Length);
byte[] salt = m_mac.CalculateMac();
m_mac.Update(PrefixPassword, 0, PrefixPassword.Length);
m_mac.Update(identity, 0, identity.Length);
byte[] password = m_mac.CalculateMac();
BigInteger verifier = m_verifierGenerator.GenerateVerifier(salt, identity, password);
TlsSrpConfig srpConfig = new TlsSrpConfig();
srpConfig.SetExplicitNG(new BigInteger[]{ m_group.N, m_group.G });
return new TlsSrpLoginParameters(identity, srpConfig, verifier, salt);
}
}
}
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