mirror of
https://github.com/shadps4-emu/ext-cryptopp.git
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343 lines
10 KiB
C++
343 lines
10 KiB
C++
// xts.cpp - written and placed in the public domain by Jeffrey Walton
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#include "pch.h"
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#include "xts.h"
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#include "misc.h"
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#include "modes.h"
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#if defined(CRYPTOPP_DEBUG)
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# include "aes.h"
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# include "threefish.h"
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#endif
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ANONYMOUS_NAMESPACE_BEGIN
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using CryptoPP::byte;
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using CryptoPP::word32;
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using CryptoPP::word64;
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using CryptoPP::GetWord;
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using CryptoPP::PutWord;
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using CryptoPP::IsPowerOf2;
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using CryptoPP::BIG_ENDIAN_ORDER;
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using CryptoPP::LITTLE_ENDIAN_ORDER;
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// Borrowed from CMAC, but little-endian representation
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inline void GF_Double(byte *k, unsigned int len)
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{
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#if defined(_M_X64) || defined(_M_ARM64) || defined(_LP64) || defined(__LP64__)
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word64 carry = 0, x;
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for (size_t i=0, idx=0; i<len/8; ++i, idx+=8)
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{
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x = GetWord<word64>(false, LITTLE_ENDIAN_ORDER, k+idx);
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word64 y = (x >> 63); x = (x << 1) + carry;
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PutWord<word64>(false, LITTLE_ENDIAN_ORDER, k+idx, x);
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carry = y;
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}
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#else
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word32 carry = 0, x;
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for (size_t i=0, idx=0; i<len/4; ++i, idx+=4)
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{
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x = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, k+idx);
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word32 y = (x >> 31); x = (x << 1) + carry;
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PutWord<word32>(false, LITTLE_ENDIAN_ORDER, k+idx, x);
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carry = y;
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}
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#endif
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#if CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS
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CRYPTOPP_ASSERT(IsPowerOf2(len));
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CRYPTOPP_ASSERT(len >= 8);
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CRYPTOPP_ASSERT(len <= 128);
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// Special case the dominant case
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if (carry && len == 16)
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{
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k[0] ^= 0x87;
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return;
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}
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if (carry)
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{
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switch (len)
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{
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case 8:
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{
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const size_t LEIDX = 8-1;
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k[LEIDX-7] ^= 0x1b;
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break;
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}
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case 16:
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{
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const size_t LEIDX = 16-1;
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k[LEIDX-15] ^= 0x87;
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break;
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}
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case 32:
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{
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// https://crypto.stackexchange.com/q/9815/10496
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// Polynomial x^256 + x^10 + x^5 + x^2 + 1
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const size_t LEIDX = 32-1;
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k[LEIDX-30] ^= 4;
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k[LEIDX-31] ^= 0x25;
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break;
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}
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case 64:
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{
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// https://crypto.stackexchange.com/q/9815/10496
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// Polynomial x^512 + x^8 + x^5 + x^2 + 1
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const size_t LEIDX = 64-1;
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k[LEIDX-62] ^= 1;
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k[LEIDX-63] ^= 0x25;
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break;
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}
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case 128:
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{
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// https://crypto.stackexchange.com/q/9815/10496
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// Polynomial x^1024 + x^19 + x^6 + x + 1
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const size_t LEIDX = 128-1;
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k[LEIDX-125] ^= 8;
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k[LEIDX-126] ^= 0x00;
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k[LEIDX-127] ^= 0x43;
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break;
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}
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default:
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CRYPTOPP_ASSERT(0);
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}
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}
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#else
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CRYPTOPP_ASSERT(len == 16);
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if (carry)
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{
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k[0] ^= 0x87;
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return;
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}
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#endif // CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS
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}
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#if defined(CRYPTOPP_DEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)
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using CryptoPP::AES;
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using CryptoPP::XTS_Mode;
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using CryptoPP::Threefish512;
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void Modes_TestInstantiations()
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{
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XTS_Mode<AES>::Encryption m0;
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XTS_Mode<AES>::Decryption m1;
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XTS_Mode<AES>::Encryption m2;
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XTS_Mode<AES>::Decryption m3;
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#if CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS
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XTS_Mode<Threefish512>::Encryption m4;
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XTS_Mode<Threefish512>::Decryption m5;
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#endif
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}
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#endif
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ANONYMOUS_NAMESPACE_END
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NAMESPACE_BEGIN(CryptoPP)
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void XTS_ModeBase::SetKey(const byte *key, size_t length, const NameValuePairs ¶ms)
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{
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CRYPTOPP_ASSERT(length % 2 == 0);
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#if (CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS == 0)
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CRYPTOPP_ASSERT(BlockSize() == 16);
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if (BlockSize() != 16)
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throw InvalidArgument(AlgorithmName() + ": block size of underlying block cipher is not 16");
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#endif
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const size_t klen = length/2;
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AccessBlockCipher().SetKey(key+0, klen, params);
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AccessTweakCipher().SetKey(key+klen, klen, params);
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ResizeBuffers();
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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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void XTS_ModeBase::Resynchronize(const byte *iv, int ivLength)
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{
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BlockOrientedCipherModeBase::Resynchronize(iv, ivLength);
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GetTweakCipher().ProcessBlock(m_register);
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}
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void XTS_ModeBase::Resynchronize(word64 sector, ByteOrder order)
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{
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SecByteBlock iv(GetTweakCipher().BlockSize());
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PutWord<word64>(false, order, iv, sector);
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std::memset(iv+8, 0x00, iv.size()-8);
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BlockOrientedCipherModeBase::Resynchronize(iv, iv.size());
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GetTweakCipher().ProcessBlock(m_register);
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}
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void XTS_ModeBase::ResizeBuffers()
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{
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BlockOrientedCipherModeBase::ResizeBuffers();
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m_workspace.New(GetBlockCipher().BlockSize());
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}
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void XTS_ModeBase::ProcessData(byte *outString, const byte *inString, size_t length)
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{
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const unsigned int blockSize = GetBlockCipher().BlockSize();
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// data unit is multiple of 16 bytes
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CRYPTOPP_ASSERT(length % blockSize == 0);
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// now encrypt the data unit, AES_BLK_BYTES at a time
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for (size_t i=0; i<length; i+=blockSize)
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{
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// merge the tweak into the input block
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xorbuf(m_workspace, inString+i, m_register, blockSize);
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// encrypt one block, merge the tweak into the output block
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GetBlockCipher().AdvancedProcessBlocks(m_workspace, m_register, outString+i, blockSize, 0);
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// Multiply T by alpha
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GF_Double(m_register, m_register.size());
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}
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}
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size_t XTS_ModeBase::ProcessLastBlock(byte *outString, size_t outLength, const byte *inString, size_t inLength)
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{
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if (IsForwardTransformation())
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return ProcessLastPlainBlock(outString, outLength, inString, inLength);
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else
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return ProcessLastCipherBlock(outString, outLength, inString, inLength);
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}
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size_t XTS_ModeBase::ProcessLastPlainBlock(byte *outString, size_t outLength, const byte *inString, size_t inLength)
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{
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// ensure output buffer is large enough
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CRYPTOPP_ASSERT(outLength >= inLength);
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// need at least a full AES block
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CRYPTOPP_ASSERT(inLength >= BlockSize());
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const unsigned int blockSize = GetBlockCipher().BlockSize();
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const unsigned int blocks = inLength / blockSize;
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const unsigned int tail = inLength % blockSize;
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outLength = inLength;
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if (tail == 0)
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{
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// Allow ProcessData to handle all the full blocks
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ProcessData(outString, inString, inLength);
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return inLength;
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}
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else if (blocks > 1)
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{
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// Allow ProcessData to handle full blocks except one
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const size_t head = (blocks-1)*blockSize;
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ProcessData(outString, inString, inLength-head);
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outString += head;
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inString += head; inLength -= head;
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}
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///// handle the full block /////
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// merge the tweak into the input block
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xorbuf(m_workspace, inString, m_register, blockSize);
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// encrypt one block, merge the tweak into the output block
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GetBlockCipher().AdvancedProcessBlocks(m_workspace, m_register, outString, blockSize, 0);
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// Multiply T by alpha
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GF_Double(m_register, m_register.size());
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///// handle final partial block /////
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inString += blockSize;
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outString += blockSize;
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const size_t len = inLength-blockSize;
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// copy in the final plaintext bytes
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std::memcpy(m_workspace, inString, len);
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// and copy out the final ciphertext bytes
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std::memcpy(outString, outString-blockSize, len);
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// "steal" ciphertext to complete the block
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std::memcpy(m_workspace+len, outString-blockSize+len, blockSize-len);
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// merge the tweak into the input block
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xorbuf(m_workspace, m_register, blockSize);
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// encrypt the final block, merge the tweak into the output block
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GetBlockCipher().AdvancedProcessBlocks(m_workspace, m_register, outString-blockSize, blockSize, 0);
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return outLength;
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}
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size_t XTS_ModeBase::ProcessLastCipherBlock(byte *outString, size_t outLength, const byte *inString, size_t inLength)
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{
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// ensure output buffer is large enough
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CRYPTOPP_ASSERT(outLength >= inLength);
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// need at least a full AES block
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CRYPTOPP_ASSERT(inLength >= BlockSize());
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const unsigned int blockSize = GetBlockCipher().BlockSize();
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const unsigned int blocks = inLength / blockSize;
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const unsigned int tail = inLength % blockSize;
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outLength = inLength;
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if (tail == 0)
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{
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// Allow ProcessData to handle all the full blocks
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ProcessData(outString, inString, inLength);
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return inLength;
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}
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else if (blocks > 1)
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{
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// Allow ProcessData to handle full blocks except one
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const size_t head = (blocks-1)*blockSize;
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ProcessData(outString, inString, inLength-head);
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outString += head;
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inString += head; inLength -= head;
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}
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SecByteBlock poly1(m_register);
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SecByteBlock poly2(m_register);
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GF_Double(poly2, poly2.size());
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///// handle final partial block /////
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inString += blockSize;
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outString += blockSize;
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const size_t len = inLength-blockSize;
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// merge the tweak into the input block
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xorbuf(m_workspace, inString-blockSize, poly2, blockSize);
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// encrypt one block, merge the tweak into the output block
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GetBlockCipher().AdvancedProcessBlocks(m_workspace, poly2, m_workspace, blockSize, 0);
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// copy in the final plaintext bytes
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std::memcpy(outString-blockSize, inString, len);
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// and copy out the final ciphertext bytes
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std::memcpy(outString, m_workspace, len);
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// "steal" ciphertext to complete the block
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std::memcpy(outString-blockSize+len, m_workspace+len, blockSize-len);
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///// handle the full previous block /////
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inString -= blockSize;
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outString -= blockSize;
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// merge the tweak into the output block
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xorbuf(m_workspace, outString, poly1, blockSize);
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// encrypt one block, merge the tweak into the input block
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GetBlockCipher().AdvancedProcessBlocks(m_workspace, poly1, outString, blockSize, 0);
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return outLength;
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}
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NAMESPACE_END
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