1 files changed, 54 insertions, 0 deletions
diff --git a/crypto/src/tls/crypto/impl/bc/BcX25519.cs b/crypto/src/tls/crypto/impl/bc/BcX25519.cs
new file mode 100644
index 000000000..c26bc5155
--- /dev/null
+++ b/crypto/src/tls/crypto/impl/bc/BcX25519.cs
@@ -0,0 +1,54 @@
+using System;
+
+using Org.BouncyCastle.Math.EC.Rfc7748;
+
+namespace Org.BouncyCastle.Tls.Crypto.Impl.BC
+{
+    /// <summary>Support class for X25519 using the BC light-weight library.</summary>
+    public class BcX25519
+        : TlsAgreement
+    {
+        protected readonly BcTlsCrypto m_crypto;
+        protected readonly byte[] m_privateKey = new byte[X25519.ScalarSize];
+        protected readonly byte[] m_peerPublicKey = new byte[X25519.PointSize];
+
+        public BcX25519(BcTlsCrypto crypto)
+        {
+            this.m_crypto = crypto;
+        }
+
+        public virtual byte[] GenerateEphemeral()
+        {
+            m_crypto.SecureRandom.NextBytes(m_privateKey);
+
+            byte[] publicKey = new byte[X25519.PointSize];
+            X25519.ScalarMultBase(m_privateKey, 0, publicKey, 0);
+            return publicKey;
+        }
+
+        public virtual void ReceivePeerValue(byte[] peerValue)
+        {
+            if (peerValue == null || peerValue.Length != X25519.PointSize)
+                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
+
+            Array.Copy(peerValue, 0, m_peerPublicKey, 0, X25519.PointSize);
+        }
+
+        public virtual TlsSecret CalculateSecret()
+        {
+            try
+            {
+                byte[] secret = new byte[X25519.PointSize];
+                if (!X25519.CalculateAgreement(m_privateKey, 0, m_peerPublicKey, 0, secret, 0))
+                    throw new TlsFatalAlert(AlertDescription.handshake_failure);
+
+                return m_crypto.AdoptLocalSecret(secret);
+            }
+            finally
+            {
+                Array.Clear(m_privateKey, 0, m_privateKey.Length);
+                Array.Clear(m_peerPublicKey, 0, m_peerPublicKey.Length);
+            }
+        }
+    }
+}