diff options
Diffstat (limited to 'CPP/7zip/Crypto/ZipCrypto.cpp')
-rwxr-xr-x | CPP/7zip/Crypto/ZipCrypto.cpp | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/CPP/7zip/Crypto/ZipCrypto.cpp b/CPP/7zip/Crypto/ZipCrypto.cpp new file mode 100755 index 00000000..fc9f8ac2 --- /dev/null +++ b/CPP/7zip/Crypto/ZipCrypto.cpp @@ -0,0 +1,131 @@ +// Crypto/ZipCrypto.cpp + +#include "StdAfx.h" + +extern "C" +{ +#include "../../../C/7zCrc.h" +} + +#include "../Common/StreamUtils.h" + +#include "RandGen.h" +#include "ZipCrypto.h" + +namespace NCrypto { +namespace NZip { + +void CCipher::UpdateKeys(Byte b) +{ + Keys[0] = CRC_UPDATE_BYTE(Keys[0], b); + Keys[1] += Keys[0] & 0xff; + Keys[1] = Keys[1] * 134775813L + 1; + Keys[2] = CRC_UPDATE_BYTE(Keys[2], (Byte)(Keys[1] >> 24)); +} + +void CCipher::SetPassword(const Byte *password, UInt32 passwordLen) +{ + Keys[0] = 305419896L; + Keys[1] = 591751049L; + Keys[2] = 878082192L; + for (UInt32 i = 0; i < passwordLen; i++) + UpdateKeys(password[i]); +} + +Byte CCipher::DecryptByteSpec() +{ + UInt32 temp = Keys[2] | 2; + return (Byte)((temp * (temp ^ 1)) >> 8); +} + +Byte CCipher::DecryptByte(Byte b) +{ + Byte c = (Byte)(b ^ DecryptByteSpec()); + UpdateKeys(c); + return c; +} + +Byte CCipher::EncryptByte(Byte b) +{ + Byte c = (Byte)(b ^ DecryptByteSpec()); + UpdateKeys(b); + return c; +} + +void CCipher::DecryptHeader(Byte *buf) +{ + for (unsigned i = 0; i < kHeaderSize; i++) + buf[i] = DecryptByte(buf[i]); +} + +void CCipher::EncryptHeader(Byte *buf) +{ + for (unsigned i = 0; i < kHeaderSize; i++) + buf[i] = EncryptByte(buf[i]); +} + +STDMETHODIMP CEncoder::CryptoSetPassword(const Byte *data, UInt32 size) +{ + _cipher.SetPassword(data, size); + return S_OK; +} + +STDMETHODIMP CEncoder::CryptoSetCRC(UInt32 crc) +{ + _crc = crc; + return S_OK; +} + +STDMETHODIMP CEncoder::Init() +{ + return S_OK; +} + +HRESULT CEncoder::WriteHeader(ISequentialOutStream *outStream) +{ + Byte header[kHeaderSize]; + g_RandomGenerator.Generate(header, kHeaderSize - 2); + + header[kHeaderSize - 1] = Byte(_crc >> 24); + header[kHeaderSize - 2] = Byte(_crc >> 16); + + _cipher.EncryptHeader(header); + return WriteStream(outStream, header, kHeaderSize); +} + +STDMETHODIMP_(UInt32) CEncoder::Filter(Byte *data, UInt32 size) +{ + UInt32 i; + for (i = 0; i < size; i++) + data[i] = _cipher.EncryptByte(data[i]); + return i; +} + +STDMETHODIMP CDecoder::CryptoSetPassword(const Byte *data, UInt32 size) +{ + _cipher.SetPassword(data, size); + return S_OK; +} + +HRESULT CDecoder::ReadHeader(ISequentialInStream *inStream) +{ + Byte header[kHeaderSize]; + RINOK(ReadStream_FAIL(inStream, header, kHeaderSize)); + _cipher.DecryptHeader(header); + return S_OK; +} + +STDMETHODIMP CDecoder::Init() +{ + return S_OK; +} + +STDMETHODIMP_(UInt32) CDecoder::Filter(Byte *data, UInt32 size) +{ + UInt32 i; + for (i = 0; i < size; i++) + data[i] = _cipher.DecryptByte(data[i]); + return i; +} + +}} |