1 files changed, 81 insertions, 0 deletions
diff --git a/zip/ZipArchive/ZipCrc32Cryptograph.cpp b/zip/ZipArchive/ZipCrc32Cryptograph.cpp
new file mode 100644
index 0000000..50a0e2b
--- /dev/null
+++ b/zip/ZipArchive/ZipCrc32Cryptograph.cpp
@@ -0,0 +1,81 @@
+////////////////////////////////////////////////////////////////////////////////
+// This source file is part of the ZipArchive library source distribution and
+// is Copyrighted 2000 - 2007 by Artpol Software - Tadeusz Dracz
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+// 
+// For the licensing details refer to the License.txt file.
+//
+// Web Site: http://www.artpol-software.com
+////////////////////////////////////////////////////////////////////////////////
+
+#include "stdafx.h"
+#include "ZipCrc32Cryptograph.h"
+
+bool CZipCrc32Cryptograph::InitDecode(CZipAutoBuffer& password, CZipFileHeader& currentFile, CZipStorage& storage)
+{
+	CryptInitKeys(password);
+	CZipAutoBuffer buf(ZIPARCHIVE_ENCR_HEADER_LEN);
+	storage.Read(buf, ZIPARCHIVE_ENCR_HEADER_LEN, false);
+	BYTE b = 0;
+	for (int i = 0; i < ZIPARCHIVE_ENCR_HEADER_LEN; i++)
+	{
+		b = buf[i]; // only temporary
+		CryptDecode((char&)b);
+	}
+	// check the last byte
+	return currentFile.IsDataDescriptor() ?
+		(BYTE(currentFile.m_uModTime >> 8) == b) : (BYTE(currentFile.m_uCrc32 >> 24) == b);
+}
+
+void CZipCrc32Cryptograph::InitEncode(CZipAutoBuffer& password, CZipFileHeader& currentFile, CZipStorage& storage)
+{
+	CZipAutoBuffer buf(ZIPARCHIVE_ENCR_HEADER_LEN);
+	// use pseudo-crc since we don't know it yet	
+	CryptInitKeys(password);
+	srand(UINT(time(NULL)));
+	// genereate pseudo-random sequence
+	char c;
+	char* buffer = (char*)buf;
+	for (int i = 0; i < ZIPARCHIVE_ENCR_HEADER_LEN - 2; i++)
+	{
+		int t1 = rand();
+		c = (char)((t1 >> 6) & 0xFF);
+		if (!c)
+			c = (char)(t1 & 0xFF);
+		CryptEncode(c);
+		buffer[i] = c;
+
+	}
+	long iCrc = (long)currentFile.m_uModTime << 16;	
+	c = (char)((iCrc >> 16) & 0xFF);
+	CryptEncode(c);
+	buffer[ZIPARCHIVE_ENCR_HEADER_LEN - 2] = c;
+	c = (char)((iCrc >> 24) & 0xFF);
+	CryptEncode(c);
+	buffer[ZIPARCHIVE_ENCR_HEADER_LEN - 1] = c;
+	storage.Write(buf, ZIPARCHIVE_ENCR_HEADER_LEN, false);
+	currentFile.m_uComprSize += ZIPARCHIVE_ENCR_HEADER_LEN;
+}
+
+void CZipCrc32Cryptograph::CryptInitKeys(CZipAutoBuffer& password)
+{
+	m_keys[0] = 305419896L;
+	m_keys[1] = 591751049L;
+	m_keys[2] = 878082192L;
+	for (DWORD i = 0; i < password.GetSize(); i++)
+		CryptUpdateKeys(password[i]);
+}
+
+void CZipCrc32Cryptograph::CryptUpdateKeys(char c)
+{	
+	m_keys[0] = CryptCRC32(m_keys[0], c);
+	m_keys[1] += m_keys[0] & 0xff;
+	m_keys[1] = m_keys[1] * 134775813L + 1;
+	c = char(m_keys[1] >> 24);
+	m_keys[2] = CryptCRC32(m_keys[2], c);
+}
+