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Assets/BestHTTP/SecureProtocol/crypto/digests/ShakeDigest.cs

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+#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
+using System;
+using System.Diagnostics;
+
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Digests
+{
+    /// <summary>
+    /// Implementation of SHAKE based on following KeccakNISTInterface.c from http://keccak.noekeon.org/
+    /// </summary>
+    /// <remarks>
+    /// Following the naming conventions used in the C source code to enable easy review of the implementation.
+    /// </remarks>
+    public class ShakeDigest
+        : KeccakDigest, IXof
+    {
+        private static int CheckBitLength(int bitLength)
+        {
+            switch (bitLength)
+            {
+            case 128:
+            case 256:
+                return bitLength;
+            default:
+                throw new ArgumentException(bitLength + " not supported for SHAKE", "bitLength");
+            }
+        }
+
+        public ShakeDigest()
+            : this(128)
+        {
+        }
+
+        public ShakeDigest(int bitLength)
+            : base(CheckBitLength(bitLength))
+        {
+        }
+
+        public ShakeDigest(ShakeDigest source)
+            : base(source)
+        {
+        }
+
+        public override string AlgorithmName
+        {
+            get { return "SHAKE" + fixedOutputLength; }
+        }
+
+        public override int DoFinal(byte[] output, int outOff)
+        {
+            return DoFinal(output, outOff, GetDigestSize());
+        }
+
+        public virtual int DoFinal(byte[] output, int outOff, int outLen)
+        {
+            DoOutput(output, outOff, outLen);
+
+            Reset();
+
+            return outLen;
+        }
+
+        public virtual int DoOutput(byte[] output, int outOff, int outLen)
+        {
+            if (!squeezing)
+            {
+                Absorb(new byte[] { 0x0F }, 0, 4);
+            }
+
+            Squeeze(output, outOff, ((long)outLen) * 8);
+
+            return outLen;
+        }
+
+        /*
+         * TODO Possible API change to support partial-byte suffixes.
+         */
+        protected override int DoFinal(byte[] output, int outOff, byte partialByte, int partialBits)
+        {
+            return DoFinal(output, outOff, GetDigestSize(), partialByte, partialBits);
+        }
+
+        /*
+         * TODO Possible API change to support partial-byte suffixes.
+         */
+        protected virtual int DoFinal(byte[] output, int outOff, int outLen, byte partialByte, int partialBits)
+        {
+            if (partialBits < 0 || partialBits > 7)
+                throw new ArgumentException("must be in the range [0,7]", "partialBits");
+
+            int finalInput = (partialByte & ((1 << partialBits) - 1)) | (0x0F << partialBits);
+            Debug.Assert(finalInput >= 0);
+            int finalBits = partialBits + 4;
+
+            if (finalBits >= 8)
+            {
+                oneByte[0] = (byte)finalInput;
+                Absorb(oneByte, 0, 8);
+                finalBits -= 8;
+                finalInput >>= 8;
+            }
+
+            if (finalBits > 0)
+            {
+                oneByte[0] = (byte)finalInput;
+                Absorb(oneByte, 0, finalBits);
+            }
+
+            Squeeze(output, outOff, ((long)outLen) * 8);
+
+            Reset();
+
+            return outLen;
+        }
+
+        public override IMemoable Copy()
+        {
+            return new ShakeDigest(this);
+        }
+    }
+}
+#endif