115 lines
2.2 KiB
C++
115 lines
2.2 KiB
C++
// Crypto/ZipCrypto.cpp
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#include "StdAfx.h"
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#include "../../../C/7zCrc.h"
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#include "../Common/StreamUtils.h"
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#include "RandGen.h"
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#include "ZipCrypto.h"
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namespace NCrypto {
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namespace NZip {
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#define UPDATE_KEYS(b) { \
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key0 = CRC_UPDATE_BYTE(key0, b); \
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key1 = (key1 + (key0 & 0xFF)) * 0x8088405 + 1; \
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key2 = CRC_UPDATE_BYTE(key2, (Byte)(key1 >> 24)); } \
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#define DECRYPT_BYTE_1 UInt32 temp = key2 | 2;
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#define DECRYPT_BYTE_2 ((Byte)((temp * (temp ^ 1)) >> 8))
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STDMETHODIMP CCipher::CryptoSetPassword(const Byte *data, UInt32 size)
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{
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UInt32 key0 = 0x12345678;
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UInt32 key1 = 0x23456789;
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UInt32 key2 = 0x34567890;
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for (UInt32 i = 0; i < size; i++)
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UPDATE_KEYS(data[i]);
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KeyMem0 = key0;
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KeyMem1 = key1;
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KeyMem2 = key2;
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return S_OK;
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}
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STDMETHODIMP CCipher::Init()
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{
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return S_OK;
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}
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HRESULT CEncoder::WriteHeader_Check16(ISequentialOutStream *outStream, UInt16 crc)
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{
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Byte h[kHeaderSize];
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/* PKZIP before 2.0 used 2 byte CRC check.
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PKZIP 2.0+ used 1 byte CRC check. It's more secure.
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We also use 1 byte CRC. */
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g_RandomGenerator.Generate(h, kHeaderSize - 1);
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// h[kHeaderSize - 2] = (Byte)(crc);
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h[kHeaderSize - 1] = (Byte)(crc >> 8);
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RestoreKeys();
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Filter(h, kHeaderSize);
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return WriteStream(outStream, h, kHeaderSize);
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}
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STDMETHODIMP_(UInt32) CEncoder::Filter(Byte *data, UInt32 size)
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{
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UInt32 key0 = this->Key0;
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UInt32 key1 = this->Key1;
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UInt32 key2 = this->Key2;
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for (UInt32 i = 0; i < size; i++)
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{
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Byte b = data[i];
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DECRYPT_BYTE_1
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data[i] = (Byte)(b ^ DECRYPT_BYTE_2);
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UPDATE_KEYS(b);
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}
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this->Key0 = key0;
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this->Key1 = key1;
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this->Key2 = key2;
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return size;
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}
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HRESULT CDecoder::ReadHeader(ISequentialInStream *inStream)
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{
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return ReadStream_FAIL(inStream, _header, kHeaderSize);
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}
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void CDecoder::Init_BeforeDecode()
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{
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RestoreKeys();
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Filter(_header, kHeaderSize);
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}
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STDMETHODIMP_(UInt32) CDecoder::Filter(Byte *data, UInt32 size)
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{
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UInt32 key0 = this->Key0;
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UInt32 key1 = this->Key1;
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UInt32 key2 = this->Key2;
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for (UInt32 i = 0; i < size; i++)
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{
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DECRYPT_BYTE_1
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Byte b = (Byte)(data[i] ^ DECRYPT_BYTE_2);
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UPDATE_KEYS(b);
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data[i] = b;
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}
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this->Key0 = key0;
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this->Key1 = key1;
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this->Key2 = key2;
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return size;
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}
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}}
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