diff --git a/crypto/src/crypto/digests/ShakeDigest.cs b/crypto/src/crypto/digests/ShakeDigest.cs
new file mode 100644
index 000000000..fd7d85681
--- /dev/null
+++ b/crypto/src/crypto/digests/ShakeDigest.cs
@@ -0,0 +1,111 @@
+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)
+ {
+ Absorb(new byte[]{ 0x0F }, 0, 4);
+
+ Squeeze(output, outOff, ((long)outLen) * 8);
+
+ Reset();
+
+ 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);
+ }
+ }
+}
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