bouncy castle chacha20-poly1305

shadowsocks-csharp/Encryption/AEAD/AEADBouncyCastleEncryptor.cs

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+using System;
+using System.Collections.Generic;
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Crypto.Modes;
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace Shadowsocks.Encryption.AEAD
+{
+    public class AEADBouncyCastleEncryptor : AEADEncryptor
+    {
+        IAeadCipher aead;
+        bool enc;
+        public AEADBouncyCastleEncryptor(string method, string password) : base(method, password)
+        {
+            aead = cipherFamily switch
+            {
+                CipherFamily.AesGcm => new GcmBlockCipher(new AesEngine()),
+                CipherFamily.Chacha20Poly1305 => new ChaCha20Poly1305(),
+                _ => throw new NotSupportedException(),
+            };
+        }
+
+        #region Cipher Info
+        private static readonly Dictionary<string, CipherInfo> _ciphers = new Dictionary<string, CipherInfo>
+        {
+            {"aes-128-gcm", new CipherInfo("aes-128-gcm", 16, 16, 12, 16, CipherFamily.AesGcm)},
+            {"aes-192-gcm", new CipherInfo("aes-192-gcm", 24, 24, 12, 16, CipherFamily.AesGcm)},
+            {"aes-256-gcm", new CipherInfo("aes-256-gcm", 32, 32, 12, 16, CipherFamily.AesGcm)},
+            {"chacha20-ietf-poly1305", new CipherInfo("chacha20-ietf-poly1305",32, 32, 12, 16, CipherFamily.Chacha20Poly1305)},
+        };
+
+        protected override Dictionary<string, CipherInfo> GetCiphers()
+        {
+            return _ciphers;
+        }
+
+        public static Dictionary<string, CipherInfo> SupportedCiphers()
+        {
+            return _ciphers;
+        }
+        #endregion
+
+        public override void InitCipher(byte[] salt, bool isEncrypt)
+        {
+            base.InitCipher(salt, isEncrypt);
+            enc = isEncrypt;
+        }
+
+        public override int CipherDecrypt(Span<byte> plain, ReadOnlySpan<byte> cipher)
+        {
+            return CipherUpdate(cipher, plain);
+        }
+
+        public override int CipherEncrypt(ReadOnlySpan<byte> plain, Span<byte> cipher)
+        {
+            return CipherUpdate(plain, cipher);
+        }
+
+        private int CipherUpdate(ReadOnlySpan<byte> i, Span<byte> o)
+        {
+            byte[] t = new byte[o.Length];
+            byte[] n = new byte[nonce.Length];
+            nonce.CopyTo(n, 0);
+            aead.Init(enc, new AeadParameters(new KeyParameter(sessionKey), tagLen * 8, n));
+
+            int r = aead.ProcessBytes(i.ToArray(), 0, i.Length, t, 0);
+            r += aead.DoFinal(t, r);
+            t.CopyTo(o);
+            return r;
+        }
+    }
+}