DataStudy/Assets/Plugins/Best HTTP/Source/Connections/TLS/Crypto/Impl/FastCbcBlockCipher.cs

#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
#pragma warning disable
using System;

using BestHTTP.Connections.TLS.Crypto.Impl;
using BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto;
using BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto.Parameters;

namespace BestHTTP.Connections.TLS.Crypto
{
    /**
    * implements Cipher-Block-Chaining (CBC) mode on top of a simple cipher.
    */
    [BestHTTP.PlatformSupport.IL2CPP.Il2CppSetOption(BestHTTP.PlatformSupport.IL2CPP.Option.NullChecks, false)]
    [BestHTTP.PlatformSupport.IL2CPP.Il2CppSetOption(BestHTTP.PlatformSupport.IL2CPP.Option.ArrayBoundsChecks, false)]
    [BestHTTP.PlatformSupport.IL2CPP.Il2CppSetOption(BestHTTP.PlatformSupport.IL2CPP.Option.DivideByZeroChecks, false)]
    [BestHTTP.PlatformSupport.IL2CPP.Il2CppEagerStaticClassConstructionAttribute]
    public class FastCbcBlockCipher
        : IBlockCipher
    {
        private byte[] IV, cbcV, cbcNextV;
        private int blockSize;
        private IBlockCipher cipher;
        private bool encrypting;

        /**
        * Basic constructor.
        *
        * @param cipher the block cipher to be used as the basis of chaining.
        */
        public FastCbcBlockCipher(
            IBlockCipher cipher)
        {
            this.cipher = cipher;
            this.blockSize = cipher.GetBlockSize();

            this.IV = new byte[blockSize];
            this.cbcV = new byte[blockSize];
            this.cbcNextV = new byte[blockSize];
        }

        /**
        * return the underlying block cipher that we are wrapping.
        *
        * @return the underlying block cipher that we are wrapping.
        */
        public IBlockCipher GetUnderlyingCipher()
        {
            return cipher;
        }

        /**
        * Initialise the cipher and, possibly, the initialisation vector (IV).
        * If an IV isn't passed as part of the parameter, the IV will be all zeros.
        *
        * @param forEncryption if true the cipher is initialised for
        *  encryption, if false for decryption.
        * @param param the key and other data required by the cipher.
        * @exception ArgumentException if the parameters argument is
        * inappropriate.
        */
        public void Init(
            bool forEncryption,
            ICipherParameters parameters)
        {
            bool oldEncrypting = this.encrypting;

            this.encrypting = forEncryption;

            if (parameters is FastParametersWithIV)
            {
                FastParametersWithIV ivParam = (FastParametersWithIV)parameters;
                byte[] iv = ivParam.GetIV();

                if (iv.Length != blockSize)
                {
                    throw new ArgumentException("initialisation vector must be the same length as block size");
                }

                Array.Copy(iv, 0, IV, 0, iv.Length);

                parameters = ivParam.Parameters;
            }

            Reset();

            // if null it's an IV changed only.
            if (parameters != null)
            {
                cipher.Init(encrypting, parameters);
            }
            else if (oldEncrypting != encrypting)
            {
                throw new ArgumentException("cannot change encrypting state without providing key.");
            }
        }

        /**
        * return the algorithm name and mode.
        *
        * @return the name of the underlying algorithm followed by "/CBC".
        */
        public string AlgorithmName
        {
            get { return cipher.AlgorithmName + "/CBC"; }
        }

        public bool IsPartialBlockOkay
        {
            get { return false; }
        }

        /**
        * return the block size of the underlying cipher.
        *
        * @return the block size of the underlying cipher.
        */
        public int GetBlockSize()
        {
            return cipher.GetBlockSize();
        }

        /**
        * Process one block of input from the array in and write it to
        * the out array.
        *
        * @param in the array containing the input data.
        * @param inOff offset into the in array the data starts at.
        * @param out the array the output data will be copied into.
        * @param outOff the offset into the out array the output will start at.
        * @exception DataLengthException if there isn't enough data in in, or
        * space in out.
        * @exception InvalidOperationException if the cipher isn't initialised.
        * @return the number of bytes processed and produced.
        */
        public int ProcessBlock(
            byte[] input,
            int inOff,
            byte[] output,
            int outOff)
        {
            return (encrypting)
                ? EncryptBlock(input, inOff, output, outOff)
                : DecryptBlock(input, inOff, output, outOff);
        }

        /**
        * reset the chaining vector back to the IV and reset the underlying
        * cipher.
        */
        public void Reset()
        {
            Array.Copy(IV, 0, cbcV, 0, IV.Length);
            Array.Clear(cbcNextV, 0, cbcNextV.Length);

            cipher.Reset();
        }

        /**
        * Do the appropriate chaining step for CBC mode encryption.
        *
        * @param in the array containing the data to be encrypted.
        * @param inOff offset into the in array the data starts at.
        * @param out the array the encrypted data will be copied into.
        * @param outOff the offset into the out array the output will start at.
        * @exception DataLengthException if there isn't enough data in in, or
        * space in out.
        * @exception InvalidOperationException if the cipher isn't initialised.
        * @return the number of bytes processed and produced.
        */
        private unsafe int EncryptBlock(
            byte[] input,
            int inOff,
            byte[] outBytes,
            int outOff)
        {
            if ((inOff + blockSize) > input.Length)
            {
                throw new DataLengthException("input buffer too short");
            }

            /*
            * XOR the cbcV and the input,
            * then encrypt the cbcV
            */
            //for (int i = 0; i < blockSize; i++)
            //{
            //    cbcV[i] ^= input[inOff + i];
            //}
            fixed (byte* pinput = input, pcbcV = cbcV)
            {
                ulong* pulongInput = (ulong*)&pinput[inOff], pulongcbcV = (ulong*)pcbcV;

                for (int i = 0; i < blockSize / 8; i++)
                    pulongcbcV[i] ^= pulongInput[i];
            }

            int length = cipher.ProcessBlock(cbcV, 0, outBytes, outOff);

            /*
            * copy ciphertext to cbcV
            */
            Array.Copy(outBytes, outOff, cbcV, 0, cbcV.Length);

            return length;
        }

        /**
        * Do the appropriate chaining step for CBC mode decryption.
        *
        * @param in the array containing the data to be decrypted.
        * @param inOff offset into the in array the data starts at.
        * @param out the array the decrypted data will be copied into.
        * @param outOff the offset into the out array the output will start at.
        * @exception DataLengthException if there isn't enough data in in, or
        * space in out.
        * @exception InvalidOperationException if the cipher isn't initialised.
        * @return the number of bytes processed and produced.
        */
        private unsafe int DecryptBlock(
            byte[] input,
            int inOff,
            byte[] outBytes,
            int outOff)
        {
            if ((inOff + blockSize) > input.Length)
            {
                throw new DataLengthException("input buffer too short");
            }

            Array.Copy(input, inOff, cbcNextV, 0, blockSize);

            int length = cipher.ProcessBlock(input, inOff, outBytes, outOff);

            /*
            * XOR the cbcV and the output
            */
            //for (int i = 0; i < blockSize; i++)
            //{
            //    outBytes[outOff + i] ^= cbcV[i];
            //}
            fixed (byte* poutBytes = outBytes, pcbcV = cbcV)
            {
                ulong* pulongBytes = (ulong*)&poutBytes[outOff], pulongcbcV = (ulong*)pcbcV;

                for (int i = 0; i < blockSize / 8; i++)
                    pulongBytes[i] ^= pulongcbcV[i];
            }

            /*
            * swap the back up buffer into next position
            */
            byte[] tmp;

            tmp = cbcV;
            cbcV = cbcNextV;
            cbcNextV = tmp;

            return length;
        }
    }

}
#pragma warning restore
#endif