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246 lines
7.3 KiB
246 lines
7.3 KiB
![]()
4 years ago
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// modes.cpp - written and placed in the public domain by Wei Dai
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#include "pch.h"
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#ifndef CRYPTOPP_IMPORTS
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#include "modes.h"
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#ifndef NDEBUG
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#include "des.h"
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#endif
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NAMESPACE_BEGIN(CryptoPP)
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#ifndef NDEBUG
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void Modes_TestInstantiations()
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{
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CFB_Mode<DES>::Encryption m0;
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CFB_Mode<DES>::Decryption m1;
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OFB_Mode<DES>::Encryption m2;
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CTR_Mode<DES>::Encryption m3;
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ECB_Mode<DES>::Encryption m4;
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CBC_Mode<DES>::Encryption m5;
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}
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#endif
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void CFB_ModePolicy::Iterate(byte *output, const byte *input, CipherDir dir, size_t iterationCount)
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{
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assert(m_cipher->IsForwardTransformation()); // CFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
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assert(m_feedbackSize == BlockSize());
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unsigned int s = BlockSize();
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if (dir == ENCRYPTION)
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{
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m_cipher->ProcessAndXorBlock(m_register, input, output);
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m_cipher->AdvancedProcessBlocks(output, input+s, output+s, (iterationCount-1)*s, 0);
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memcpy(m_register, output+(iterationCount-1)*s, s);
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}
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else
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{
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memcpy(m_temp, input+(iterationCount-1)*s, s); // make copy first in case of in-place decryption
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m_cipher->AdvancedProcessBlocks(input, input+s, output+s, (iterationCount-1)*s, BlockTransformation::BT_ReverseDirection);
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m_cipher->ProcessAndXorBlock(m_register, input, output);
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memcpy(m_register, m_temp, s);
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}
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}
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void CFB_ModePolicy::TransformRegister()
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{
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assert(m_cipher->IsForwardTransformation()); // CFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
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m_cipher->ProcessBlock(m_register, m_temp);
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unsigned int updateSize = BlockSize()-m_feedbackSize;
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memmove_s(m_register, m_register.size(), m_register+m_feedbackSize, updateSize);
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memcpy_s(m_register+updateSize, m_register.size()-updateSize, m_temp, m_feedbackSize);
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}
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void CFB_ModePolicy::CipherResynchronize(const byte *iv, size_t length)
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{
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assert(length == BlockSize());
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CopyOrZero(m_register, iv, length);
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TransformRegister();
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}
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void CFB_ModePolicy::SetFeedbackSize(unsigned int feedbackSize)
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{
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if (feedbackSize > BlockSize())
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throw InvalidArgument("CFB_Mode: invalid feedback size");
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m_feedbackSize = feedbackSize ? feedbackSize : BlockSize();
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}
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void CFB_ModePolicy::ResizeBuffers()
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{
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CipherModeBase::ResizeBuffers();
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m_temp.New(BlockSize());
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}
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void OFB_ModePolicy::WriteKeystream(byte *keystreamBuffer, size_t iterationCount)
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{
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assert(m_cipher->IsForwardTransformation()); // OFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
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unsigned int s = BlockSize();
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m_cipher->ProcessBlock(m_register, keystreamBuffer);
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if (iterationCount > 1)
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m_cipher->AdvancedProcessBlocks(keystreamBuffer, NULL, keystreamBuffer+s, s*(iterationCount-1), 0);
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memcpy(m_register, keystreamBuffer+s*(iterationCount-1), s);
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}
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void OFB_ModePolicy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)
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{
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assert(length == BlockSize());
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CopyOrZero(m_register, iv, length);
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}
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void CTR_ModePolicy::SeekToIteration(lword iterationCount)
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{
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int carry=0;
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for (int i=BlockSize()-1; i>=0; i--)
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{
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unsigned int sum = m_register[i] + byte(iterationCount) + carry;
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m_counterArray[i] = (byte) sum;
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carry = sum >> 8;
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iterationCount >>= 8;
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}
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}
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void CTR_ModePolicy::IncrementCounterBy256()
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{
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IncrementCounterByOne(m_counterArray, BlockSize()-1);
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}
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void CTR_ModePolicy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
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{
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assert(m_cipher->IsForwardTransformation()); // CTR mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
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unsigned int s = BlockSize();
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unsigned int inputIncrement = input ? s : 0;
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while (iterationCount)
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{
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byte lsb = m_counterArray[s-1];
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size_t blocks = UnsignedMin(iterationCount, 256U-lsb);
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m_cipher->AdvancedProcessBlocks(m_counterArray, input, output, blocks*s, BlockTransformation::BT_InBlockIsCounter|BlockTransformation::BT_AllowParallel);
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if ((m_counterArray[s-1] = lsb + (byte)blocks) == 0)
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IncrementCounterBy256();
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output += blocks*s;
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input += blocks*inputIncrement;
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iterationCount -= blocks;
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}
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}
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void CTR_ModePolicy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)
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{
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assert(length == BlockSize());
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CopyOrZero(m_register, iv, length);
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m_counterArray = m_register;
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}
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void BlockOrientedCipherModeBase::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms)
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{
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m_cipher->SetKey(key, length, params);
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ResizeBuffers();
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if (IsResynchronizable())
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{
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size_t ivLength;
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const byte *iv = GetIVAndThrowIfInvalid(params, ivLength);
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Resynchronize(iv, (int)ivLength);
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}
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}
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void ECB_OneWay::ProcessData(byte *outString, const byte *inString, size_t length)
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{
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assert(length%BlockSize()==0);
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m_cipher->AdvancedProcessBlocks(inString, NULL, outString, length, BlockTransformation::BT_AllowParallel);
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}
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void CBC_Encryption::ProcessData(byte *outString, const byte *inString, size_t length)
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{
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if (!length)
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return;
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assert(length%BlockSize()==0);
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unsigned int blockSize = BlockSize();
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m_cipher->AdvancedProcessBlocks(inString, m_register, outString, blockSize, BlockTransformation::BT_XorInput);
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if (length > blockSize)
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m_cipher->AdvancedProcessBlocks(inString+blockSize, outString, outString+blockSize, length-blockSize, BlockTransformation::BT_XorInput);
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memcpy(m_register, outString + length - blockSize, blockSize);
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}
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void CBC_CTS_Encryption::ProcessLastBlock(byte *outString, const byte *inString, size_t length)
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{
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if (length <= BlockSize())
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{
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if (!m_stolenIV)
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throw InvalidArgument("CBC_Encryption: message is too short for ciphertext stealing");
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// steal from IV
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memcpy(outString, m_register, length);
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outString = m_stolenIV;
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}
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else
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{
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// steal from next to last block
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xorbuf(m_register, inString, BlockSize());
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m_cipher->ProcessBlock(m_register);
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inString += BlockSize();
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length -= BlockSize();
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memcpy(outString+BlockSize(), m_register, length);
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}
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// output last full ciphertext block
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xorbuf(m_register, inString, length);
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m_cipher->ProcessBlock(m_register);
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memcpy(outString, m_register, BlockSize());
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}
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void CBC_Decryption::ProcessData(byte *outString, const byte *inString, size_t length)
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{
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if (!length)
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return;
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assert(length%BlockSize()==0);
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unsigned int blockSize = BlockSize();
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memcpy(m_temp, inString+length-blockSize, blockSize); // save copy now in case of in-place decryption
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if (length > blockSize)
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m_cipher->AdvancedProcessBlocks(inString+blockSize, inString, outString+blockSize, length-blockSize, BlockTransformation::BT_ReverseDirection|BlockTransformation::BT_AllowParallel);
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m_cipher->ProcessAndXorBlock(inString, m_register, outString);
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m_register.swap(m_temp);
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}
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void CBC_CTS_Decryption::ProcessLastBlock(byte *outString, const byte *inString, size_t length)
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{
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const byte *pn, *pn1;
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bool stealIV = length <= BlockSize();
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if (stealIV)
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{
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pn = inString;
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pn1 = m_register;
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}
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else
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{
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pn = inString + BlockSize();
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pn1 = inString;
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length -= BlockSize();
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}
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// decrypt last partial plaintext block
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memcpy(m_temp, pn1, BlockSize());
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m_cipher->ProcessBlock(m_temp);
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xorbuf(m_temp, pn, length);
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if (stealIV)
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memcpy(outString, m_temp, length);
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else
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{
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memcpy(outString+BlockSize(), m_temp, length);
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// decrypt next to last plaintext block
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memcpy(m_temp, pn, length);
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m_cipher->ProcessBlock(m_temp);
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xorbuf(outString, m_temp, m_register, BlockSize());
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}
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}
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NAMESPACE_END
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#endif
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