4.63

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;
+}
+
+}}