#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR) #pragma warning disable using System; using System.Diagnostics; using BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto; using BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto.Parameters; namespace BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto.Modes { /** * A Cipher Text Stealing (CTS) mode cipher. CTS allows block ciphers to * be used to produce cipher text which is the same outLength as the plain text. */ public class CtsBlockCipher : BufferedBlockCipher { private readonly int blockSize; /** * Create a buffered block cipher that uses Cipher Text Stealing * * @param cipher the underlying block cipher this buffering object wraps. */ public CtsBlockCipher( IBlockCipher cipher) { // TODO Should this test for acceptable ones instead? if (cipher is OfbBlockCipher || cipher is CfbBlockCipher) throw new ArgumentException("CtsBlockCipher can only accept ECB, or CBC ciphers"); this.cipher = cipher; blockSize = cipher.GetBlockSize(); buf = new byte[blockSize * 2]; bufOff = 0; } /** * return the size of the output buffer required for an update of 'length' bytes. * * @param length the outLength of the input. * @return the space required to accommodate a call to update * with length bytes of input. */ public override int GetUpdateOutputSize( int length) { int total = length + bufOff; int leftOver = total % buf.Length; if (leftOver == 0) { return total - buf.Length; } return total - leftOver; } /** * return the size of the output buffer required for an update plus a * doFinal with an input of length bytes. * * @param length the outLength of the input. * @return the space required to accommodate a call to update and doFinal * with length bytes of input. */ public override int GetOutputSize( int length) { return length + bufOff; } /** * process a single byte, producing an output block if necessary. * * @param in the input byte. * @param out the space for any output that might be produced. * @param outOff the offset from which the output will be copied. * @return the number of output bytes copied to out. * @exception DataLengthException if there isn't enough space in out. * @exception InvalidOperationException if the cipher isn't initialised. */ public override int ProcessByte( byte input, byte[] output, int outOff) { int resultLen = 0; if (bufOff == buf.Length) { resultLen = cipher.ProcessBlock(buf, 0, output, outOff); Debug.Assert(resultLen == blockSize); Array.Copy(buf, blockSize, buf, 0, blockSize); bufOff = blockSize; } buf[bufOff++] = input; return resultLen; } /** * process an array of bytes, producing output if necessary. * * @param in the input byte array. * @param inOff the offset at which the input data starts. * @param length the number of bytes to be copied out of the input array. * @param out the space for any output that might be produced. * @param outOff the offset from which the output will be copied. * @return the number of output bytes copied to out. * @exception DataLengthException if there isn't enough space in out. * @exception InvalidOperationException if the cipher isn't initialised. */ public override int ProcessBytes( byte[] input, int inOff, int length, byte[] output, int outOff) { if (length < 0) { throw new ArgumentException("Can't have a negative input outLength!"); } int blockSize = GetBlockSize(); int outLength = GetUpdateOutputSize(length); if (outLength > 0) { if ((outOff + outLength) > output.Length) { throw new DataLengthException("output buffer too short"); } } int resultLen = 0; int gapLen = buf.Length - bufOff; if (length > gapLen) { Array.Copy(input, inOff, buf, bufOff, gapLen); resultLen += cipher.ProcessBlock(buf, 0, output, outOff); Array.Copy(buf, blockSize, buf, 0, blockSize); bufOff = blockSize; length -= gapLen; inOff += gapLen; while (length > blockSize) { Array.Copy(input, inOff, buf, bufOff, blockSize); resultLen += cipher.ProcessBlock(buf, 0, output, outOff + resultLen); Array.Copy(buf, blockSize, buf, 0, blockSize); length -= blockSize; inOff += blockSize; } } Array.Copy(input, inOff, buf, bufOff, length); bufOff += length; return resultLen; } /** * Process the last block in the buffer. * * @param out the array the block currently being held is copied into. * @param outOff the offset at which the copying starts. * @return the number of output bytes copied to out. * @exception DataLengthException if there is insufficient space in out for * the output. * @exception InvalidOperationException if the underlying cipher is not * initialised. * @exception InvalidCipherTextException if cipher text decrypts wrongly (in * case the exception will never Get thrown). */ public override int DoFinal( byte[] output, int outOff) { if (bufOff + outOff > output.Length) { throw new DataLengthException("output buffer too small in doFinal"); } int blockSize = cipher.GetBlockSize(); int length = bufOff - blockSize; byte[] block = new byte[blockSize]; if (forEncryption) { cipher.ProcessBlock(buf, 0, block, 0); if (bufOff < blockSize) { throw new DataLengthException("need at least one block of input for CTS"); } for (int i = bufOff; i != buf.Length; i++) { buf[i] = block[i - blockSize]; } for (int i = blockSize; i != bufOff; i++) { buf[i] ^= block[i - blockSize]; } IBlockCipher c = (cipher is CbcBlockCipher) ? ((CbcBlockCipher)cipher).GetUnderlyingCipher() : cipher; c.ProcessBlock(buf, blockSize, output, outOff); Array.Copy(block, 0, output, outOff + blockSize, length); } else { byte[] lastBlock = new byte[blockSize]; IBlockCipher c = (cipher is CbcBlockCipher) ? ((CbcBlockCipher)cipher).GetUnderlyingCipher() : cipher; c.ProcessBlock(buf, 0, block, 0); for (int i = blockSize; i != bufOff; i++) { lastBlock[i - blockSize] = (byte)(block[i - blockSize] ^ buf[i]); } Array.Copy(buf, blockSize, block, 0, length); cipher.ProcessBlock(block, 0, output, outOff); Array.Copy(lastBlock, 0, output, outOff + blockSize, length); } int offset = bufOff; Reset(); return offset; } } } #pragma warning restore #endif