diff --git a/src/Tmds.Ssh/Curve25519KeyExchange.cs b/src/Tmds.Ssh/Curve25519KeyExchange.cs
index eb859738..63e9f151 100644
--- a/src/Tmds.Ssh/Curve25519KeyExchange.cs
+++ b/src/Tmds.Ssh/Curve25519KeyExchange.cs
@@ -62,7 +62,7 @@ public override async Task<KeyExchangeOutput> TryExchangeAsync(KeyExchangeContex
         return CalculateKeyExchangeOutput(input, sequencePool, sharedSecret, exchangeHash, _hashAlgorithmName);
     }
 
-    private static byte[] CalculateExchangeHash(SequencePool sequencePool, SshConnectionInfo connectionInfo, ReadOnlyPacket clientKexInitMsg, ReadOnlyPacket serverKexInitMsg, byte[] public_host_key, byte[] q_c, byte[] q_s, byte[] sharedSecret, HashAlgorithmName hashAlgorithmName)
+    protected static byte[] CalculateExchangeHash(SequencePool sequencePool, SshConnectionInfo connectionInfo, ReadOnlyPacket clientKexInitMsg, ReadOnlyPacket serverKexInitMsg, byte[] public_host_key, byte[] q_c, byte[] q_s, byte[] sharedSecret, HashAlgorithmName hashAlgorithmName)
     {
         /*
             string   V_C, client's identification string (CR and LF excluded)
@@ -105,7 +105,7 @@ private static byte[] DeriveSharedSecret(AsymmetricKeyParameter privateKey, Asym
         return sharedSecret.ToMPIntByteArray();
     }
 
-    private static Packet CreateEcdhInitMessage(SequencePool sequencePool, ReadOnlySpan<byte> q_c)
+    protected static Packet CreateEcdhInitMessage(SequencePool sequencePool, ReadOnlySpan<byte> q_c)
     {
         using var packet = sequencePool.RentPacket();
         var writer = packet.GetWriter();
@@ -114,7 +114,7 @@ private static Packet CreateEcdhInitMessage(SequencePool sequencePool, ReadOnlyS
         return packet.Move();
     }
 
-    private static (
+    protected static (
         SshKey public_host_key,
         byte[] q_s,
         ReadOnlySequence<byte> exchange_hash_signature)
diff --git a/src/Tmds.Ssh/SNtruPrime761X25519Sha512KeyExchange.cs b/src/Tmds.Ssh/SNtruPrime761X25519Sha512KeyExchange.cs
index 9f8b6d67..d8bf68c8 100644
--- a/src/Tmds.Ssh/SNtruPrime761X25519Sha512KeyExchange.cs
+++ b/src/Tmds.Ssh/SNtruPrime761X25519Sha512KeyExchange.cs
@@ -1,4 +1,6 @@
-using System.Buffers;
+// This file is part of Tmds.Ssh which is released under MIT.
+// See file LICENSE for full license details.
+
 using System.Security.Cryptography;
 using Microsoft.Extensions.Logging;
 using Org.BouncyCastle.Crypto;
@@ -11,7 +13,7 @@
 
 namespace Tmds.Ssh;
 
-sealed class SNtruPrime761X25519Sha512KeyExchange : KeyExchange
+sealed class SNtruPrime761X25519Sha512KeyExchange : Curve25519KeyExchange
 {
     private readonly SNtruPrimeParameters _sntruPrimeParameters = SNtruPrimeParameters.sntrup761;
     private readonly HashAlgorithmName _hashAlgorithmName = HashAlgorithmName.SHA512;
@@ -68,38 +70,6 @@ public override async Task<KeyExchangeOutput> TryExchangeAsync(KeyExchangeContex
         return CalculateKeyExchangeOutput(input, sequencePool, sharedSecret, exchangeHash, _hashAlgorithmName);
     }
 
-    private static byte[] CalculateExchangeHash(SequencePool sequencePool, SshConnectionInfo connectionInfo, ReadOnlyPacket clientKexInitMsg, ReadOnlyPacket serverKexInitMsg, byte[] public_host_key, byte[] q_c, byte[] q_s, byte[] sharedSecret, HashAlgorithmName hashAlgorithmName)
-    {
-        /*
-            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
-            string   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.WriteString(sharedSecret);
-
-        using IncrementalHash hash = IncrementalHash.CreateHash(hashAlgorithmName);
-        foreach (var segment in sequence.AsReadOnlySequence())
-        {
-            hash.AppendData(segment.Span);
-        }
-        return hash.GetHashAndReset();
-    }
-
-
     private static byte[] DeriveSharedSecret(AsymmetricKeyParameter sntrup761PrivateKey, AsymmetricKeyParameter x25519PrivateKey, byte[] q_s)
     {
         var sntrup761Extractor = new SNtruPrimeKemExtractor((SNtruPrimePrivateKeyParameters)sntrup761PrivateKey);
@@ -118,31 +88,4 @@ private static byte[] DeriveSharedSecret(AsymmetricKeyParameter sntrup761Private
         rawSecretAgreement.AsSpan().Clear();
         return sharedSecret;
     }
-
-    private static Packet CreateEcdhInitMessage(SequencePool sequencePool, ReadOnlySpan<byte> q_c)
-    {
-        using var packet = sequencePool.RentPacket();
-        var writer = packet.GetWriter();
-        writer.WriteMessageId(MessageId.SSH_MSG_KEX_ECDH_INIT);
-        writer.WriteString(q_c);
-        return packet.Move();
-    }
-
-    private static (
-        SshKey public_host_key,
-        byte[] q_s,
-        ReadOnlySequence<byte> exchange_hash_signature)
-        ParceEcdhReply(ReadOnlyPacket packet)
-    {
-        var reader = packet.GetReader();
-        reader.ReadMessageId(MessageId.SSH_MSG_KEX_ECDH_REPLY);
-        SshKey public_host_key = reader.ReadSshKey();
-        byte[] q_s = reader.ReadStringAsByteArray();
-        ReadOnlySequence<byte> exchange_hash_signature = reader.ReadStringAsBytes();
-        reader.ReadEnd();
-        return (
-            public_host_key,
-            q_s,
-            exchange_hash_signature);
-    }
 }