private byte[] CalculateExchangeHash(SequencePool sequencePool, SshConnectionInfo connectionInfo, Packet clientKexInitMsg, Packet serverKexInitMsg, ReadOnlySequence <byte> public_host_key, ECPoint q_c, ECPoint q_s, BigInteger sharedSecret)
{
/*
* string V_C, client's identification string (CR and LF excluded)
* string V_S, server's identification string (CR and LF excluded)
* string I_C, payload of the client's SSH_MSG_KEXINIT
* string I_S, payload of the server's SSH_MSG_KEXINIT
* string K_S, server's public host key
* string Q_C, client's ephemeral public key octet string
* string Q_S, server's ephemeral public key octet string
* mpint K, shared secret
*/
using Sequence sequence = sequencePool.RentSequence();
var writer = new SequenceWriter(sequence);
writer.WriteString(connectionInfo.ClientIdentificationString !);
writer.WriteString(connectionInfo.ServerIdentificationString !);
writer.WriteString(clientKexInitMsg.Payload);
writer.WriteString(serverKexInitMsg.Payload);
writer.WriteString(public_host_key);
writer.WriteString(q_c);
writer.WriteString(q_s);
writer.WriteMPInt(sharedSecret);
using IncrementalHash hash = IncrementalHash.CreateHash(_hashAlgorithmName);
foreach (var segment in sequence.AsReadOnlySequence())
{
hash.AppendData(segment.Span);
}
return(hash.GetHashAndReset());
}
private byte[] Hash(SequencePool sequencePool, BigInteger sharedSecret, byte[] exchangeHash, byte c, byte[] sessionId, int hashLength)
{
// https://tools.ietf.org/html/rfc4253#section-7.2
byte[] hashRv = new byte[hashLength];
int hashOffset = 0;
// TODO: handle 'If the key length needed is longer than the output of the HASH'
// HASH(K || H || c || session_id)
using Sequence sequence = sequencePool.RentSequence();
var writer = new SequenceWriter(sequence);
writer.WriteMPInt(sharedSecret);
writer.Write(exchangeHash);
writer.WriteByte(c);
writer.Write(sessionId);
using IncrementalHash hash = IncrementalHash.CreateHash(_hashAlgorithmName);
foreach (var segment in sequence.AsReadOnlySequence())
{
hash.AppendData(segment.Span);
}
byte[] K1 = hash.GetHashAndReset();
Append(hashRv, K1, ref hashOffset);
while (hashOffset != hashRv.Length)
{
// TODO: handle 'If the key length needed is longer than the output of the HASH'
// K3 = HASH(K || H || K1 || K2)
throw new NotSupportedException();
}
return(hashRv);
public void Transform(Span <byte> prefix, ReadOnlySequence <byte> data, Span <byte> suffix, Sequence output)
{
var writer = new SequenceWriter(output);
writer.Write(prefix);
writer.Write(data);
writer.Write(suffix);
}
public override void AppendPublicKey(ref SequenceWriter writer)
{
RSAParameters parameters = _rsa.ExportParameters(includePrivateParameters: false);
using var innerData = writer.SequencePool.RentSequence();
var innerWriter = new SequenceWriter(innerData);
innerWriter.WriteString(AlgorithmNames.SshRsa);
innerWriter.WriteMPInt(parameters.Exponent);
innerWriter.WriteMPInt(parameters.Modulus);
writer.WriteString(innerData.AsReadOnlySequence());
}
private static Packet CreatePublicKeyRequestMessage(SequencePool sequencePool, string userName, byte[] sessionId, PrivateKey privateKey)
{
/*
* byte SSH_MSG_USERAUTH_REQUEST
* string user name
* string service name
* string "publickey"
* boolean TRUE
* string public key algorithm name
* string public key to be used for authentication
* string signature
*/
using var packet = sequencePool.RentPacket();
var writer = packet.GetWriter();
writer.WriteByte(MessageNumber.SSH_MSG_USERAUTH_REQUEST);
writer.WriteString(userName);
writer.WriteString("ssh-connection");
writer.WriteString("publickey");
writer.WriteBoolean(true);
writer.WriteString(privateKey.Format);
privateKey.AppendPublicKey(ref writer);
{
/*
* string session identifier
* byte SSH_MSG_USERAUTH_REQUEST
* string user name
* string service name
* string "publickey"
* boolean TRUE
* string public key algorithm name
* string public key to be used for authentication
*/
using var signatureData = sequencePool.RentSequence();
var signatureWriter = new SequenceWriter(signatureData);
signatureWriter.WriteString(sessionId);
signatureWriter.WriteByte(MessageNumber.SSH_MSG_USERAUTH_REQUEST);
signatureWriter.WriteString(userName);
signatureWriter.WriteString("ssh-connection");
signatureWriter.WriteString("publickey");
signatureWriter.WriteBoolean(true);
signatureWriter.WriteString(privateKey.Format);
privateKey.AppendPublicKey(ref signatureWriter);
privateKey.AppendSignature(ref writer, signatureData.AsReadOnlySequence());
}
return(packet.Move());
}
public override void AppendSignature(ref SequenceWriter writer, ReadOnlySequence <byte> data)
{
using var innerData = writer.SequencePool.RentSequence();
var innerWriter = new SequenceWriter(innerData);
innerWriter.WriteString(AlgorithmNames.SshRsa);
int signatureLength = _rsa.KeySize / 8;
byte[] signature = new byte[signatureLength];
if (!_rsa.TrySignData(data.ToArray(), signature, HashAlgorithmName.SHA1, RSASignaturePadding.Pkcs1, out int bytesWritten) ||
bytesWritten != signatureLength)
{
throw new InvalidOperationException("Unable to sign data.");
}
innerWriter.WriteString(signature);
writer.WriteString(innerData.AsReadOnlySequence());
}
public abstract void AppendSignature(ref SequenceWriter writer, ReadOnlySequence <byte> data);
public abstract void AppendPublicKey(ref SequenceWriter writer);