3.13

7zip/Crypto/Zip/ZipCrypto.cpp

@@ -0,0 +1,65 @@
+// Crypto/ZipCrypto.cpp
+
+#include "StdAfx.h"
+
+#include "ZipCipher.h"
+#include "Common/Crc.h"
+
+namespace NCrypto {
+namespace NZip {
+
+inline UINT32 CRC32(UINT32 c, BYTE  b)
+{
+  return CCRC::Table[(c ^ b) & 0xFF] ^ (c >> 8);
+}
+
+void CCipher::UpdateKeys(BYTE b)
+{
+  Keys[0] = CRC32(Keys[0], b);
+  Keys[1] += Keys[0] & 0xff;
+  Keys[1] = Keys[1] * 134775813L + 1;
+  Keys[2] = CRC32(Keys[2], Keys[1] >> 24);
+}
+
+void CCipher::SetPassword(const BYTE *password, UINT32 passwordLength)
+{
+  Keys[0] = 305419896L;
+  Keys[1] = 591751049L;
+  Keys[2] = 878082192L;
+  for (UINT32 i = 0; i < passwordLength; i++)
+    UpdateKeys(password[i]);
+}
+
+BYTE CCipher::DecryptByteSpec()
+{
+  UINT32 temp = Keys[2] | 2;
+  return (temp * (temp ^ 1)) >> 8;
+}
+
+BYTE CCipher::DecryptByte(BYTE encryptedByte)
+{
+  BYTE c = encryptedByte ^ DecryptByteSpec();
+  UpdateKeys(c);
+  return c;
+}
+
+BYTE CCipher::EncryptByte(BYTE b)
+{
+  BYTE c = b ^ DecryptByteSpec();
+  UpdateKeys(b);
+  return c;
+}
+
+void CCipher::DecryptHeader(BYTE *buffer)
+{
+  for (int i = 0; i < 12; i++)
+    buffer[i] = DecryptByte(buffer[i]);
+}
+
+void CCipher::EncryptHeader(BYTE *buffer)
+{
+  for (int i = 0; i < 12; i++)
+    buffer[i] = EncryptByte(buffer[i]);
+}
+
+}}