using Org.BouncyCastle.Math; using Org.BouncyCastle.Tls.Crypto; using Org.BouncyCastle.Utilities; using Org.BouncyCastle.Utilities.IO; using System; using System.IO; namespace Org.BouncyCastle.Tls { public class TlsSrpKeyExchange : AbstractTlsKeyExchange { protected TlsSrpIdentity m_srpIdentity; protected TlsSrpConfigVerifier m_srpConfigVerifier; protected TlsCertificate m_serverCertificate; protected byte[] m_srpSalt; protected TlsSrp6Client m_srpClient; protected TlsSrpLoginParameters m_srpLoginParameters; protected TlsCredentialedSigner m_serverCredentials; protected TlsSrp6Server m_srpServer; protected BigInteger m_srpPeerCredentials; public override bool RequiresServerKeyExchange => true; private static int CheckKeyExchange(int keyExchange) { if ((uint)(keyExchange - 21) <= 2) return keyExchange; throw new ArgumentException("unsupported key exchange algorithm", "keyExchange"); } public TlsSrpKeyExchange(int keyExchange, TlsSrpIdentity srpIdentity, TlsSrpConfigVerifier srpConfigVerifier) : base(CheckKeyExchange(keyExchange)) { m_srpIdentity = srpIdentity; m_srpConfigVerifier = srpConfigVerifier; } public TlsSrpKeyExchange(int keyExchange, TlsSrpLoginParameters srpLoginParameters) : base(CheckKeyExchange(keyExchange)) { m_srpLoginParameters = srpLoginParameters; } public override void SkipServerCredentials() { if (m_keyExchange != 21) throw new TlsFatalAlert(80); } public override void ProcessServerCredentials(TlsCredentials serverCredentials) { if (m_keyExchange == 21) throw new TlsFatalAlert(80); m_serverCredentials = TlsUtilities.RequireSignerCredentials(serverCredentials); } public override void ProcessServerCertificate(Certificate serverCertificate) { if (m_keyExchange == 21) throw new TlsFatalAlert(80); m_serverCertificate = serverCertificate.GetCertificateAt(0); } public override byte[] GenerateServerKeyExchange() { TlsSrpConfig config = m_srpLoginParameters.Config; m_srpServer = m_context.Crypto.CreateSrp6Server(config, m_srpLoginParameters.Verifier); BigInteger b = m_srpServer.GenerateServerCredentials(); BigInteger[] explicitNG = config.GetExplicitNG(); ServerSrpParams serverSrpParams = new ServerSrpParams(explicitNG[0], explicitNG[1], m_srpLoginParameters.Salt, b); DigestInputBuffer digestInputBuffer = new DigestInputBuffer(); serverSrpParams.Encode(digestInputBuffer); if (m_serverCredentials != null) TlsUtilities.GenerateServerKeyExchangeSignature(m_context, m_serverCredentials, digestInputBuffer); return digestInputBuffer.ToArray(); } public override void ProcessServerKeyExchange(Stream input) { DigestInputBuffer digestInputBuffer = null; Stream input2 = input; if (m_keyExchange != 21) { digestInputBuffer = new DigestInputBuffer(); input2 = new TeeInputStream(input, digestInputBuffer); } ServerSrpParams serverSrpParams = ServerSrpParams.Parse(input2); if (digestInputBuffer != null) TlsUtilities.VerifyServerKeyExchangeSignature(m_context, input, m_serverCertificate, digestInputBuffer); TlsSrpConfig tlsSrpConfig = new TlsSrpConfig(); tlsSrpConfig.SetExplicitNG(new BigInteger[2] { serverSrpParams.N, serverSrpParams.G }); if (!m_srpConfigVerifier.Accept(tlsSrpConfig)) throw new TlsFatalAlert(71); m_srpSalt = serverSrpParams.S; m_srpPeerCredentials = ValidatePublicValue(serverSrpParams.N, serverSrpParams.B); m_srpClient = m_context.Crypto.CreateSrp6Client(tlsSrpConfig); } public override void ProcessClientCredentials(TlsCredentials clientCredentials) { throw new TlsFatalAlert(80); } public override void GenerateClientKeyExchange(Stream output) { byte[] srpIdentity = m_srpIdentity.GetSrpIdentity(); byte[] srpPassword = m_srpIdentity.GetSrpPassword(); TlsSrpUtilities.WriteSrpParameter(m_srpClient.GenerateClientCredentials(m_srpSalt, srpIdentity, srpPassword), output); m_context.SecurityParameters.m_srpIdentity = Arrays.Clone(srpIdentity); } public override void ProcessClientKeyExchange(Stream input) { m_srpPeerCredentials = ValidatePublicValue(m_srpLoginParameters.Config.GetExplicitNG()[0], TlsSrpUtilities.ReadSrpParameter(input)); m_context.SecurityParameters.m_srpIdentity = Arrays.Clone(m_srpLoginParameters.Identity); } public override TlsSecret GeneratePreMasterSecret() { BigInteger n = (m_srpServer != null) ? m_srpServer.CalculateSecret(m_srpPeerCredentials) : m_srpClient.CalculateSecret(m_srpPeerCredentials); return m_context.Crypto.CreateSecret(BigIntegers.AsUnsignedByteArray(n)); } protected static BigInteger ValidatePublicValue(BigInteger N, BigInteger val) { val = val.Mod(N); if (val.Equals(BigInteger.Zero)) throw new TlsFatalAlert(47); return val; } } }