Add an ARC4 implementation

CMakeLists.txt

@@ -20,7 +20,8 @@ macro(suboption _var _comment _type _default)
 endmacro()
 
 option(STRICT_USE "Abort if there are missing optional dependencies"  OFF)
-option(USE_LZMA "Build lzma decompression support" ON)
+option(USE_ARC4 "Build ARC4 decryption support" ON)
+option(USE_LZMA "Build LZMA decompression support" ON)
 set(WITH_CONV CACHE STRING "The library to use for charset conversions")
 option(DEBUG_EXTRA "Expensive debug options" OFF)
 option(SET_WARNING_FLAGS "Adjust compiler warning flags" ON)
@@ -117,6 +118,10 @@ endif()
 
 unset(LIBRARIES)
 
+if(USE_ARC4)
+	set(INNOEXTRACT_HAVE_ARC4 1)
+endif()
+
 if(USE_LZMA)
 	find_package(LZMA REQUIRED)
 	check_link_library(LZMA LZMA_LIBRARIES)
@@ -298,6 +303,8 @@ set(INNOEXTRACT_SOURCES
 	
 	src/crypto/adler32.hpp
 	src/crypto/adler32.cpp
+	src/crypto/arc4.hpp if INNOEXTRACT_HAVE_ARC4
+	src/crypto/arc4.cpp if INNOEXTRACT_HAVE_ARC4
 	src/crypto/checksum.hpp
 	src/crypto/checksum.cpp
 	src/crypto/crc32.hpp
@@ -446,6 +453,10 @@ elseif(NOT DEBUG AND NOT CMAKE_BUILD_TYPE STREQUAL "Release")
 	set(BUILD_TYPE_SUFFIX "${BUILD_TYPE_SUFFIX} without debug output")
 endif()
 message(" - Build type: ${CMAKE_BUILD_TYPE}${BUILD_TYPE_SUFFIX}")
+print_configuration("ARC4 decryption" FIRST
+	INNOEXTRACT_HAVE_ARC4 "enabled"
+	1                     "disabled"
+)
 print_configuration("LZMA decompression" FIRST
 	INNOEXTRACT_HAVE_LZMA "enabled"
 	1                     "disabled"

README.md

@@ -43,6 +43,7 @@ Build options:
 
 | Option                   | Default   | Description |
 |:------------------------ |:---------:|:----------- |
+| `USE_ARC4`               | `ON`      | Build ARC4 decryption support.
 | `USE_LZMA`               | `ON`      | Use `liblzma`.
 | `WITH_CONV`              | *not set* | The charset conversion library to use. Valid values are `iconv`, `win32` and `builtin`^1. If not set, a library appropriate for the target platform will be chosen.
 | `CMAKE_BUILD_TYPE`       | `Release` | Set to `Debug` to enable debug output.

src/configure.hpp.in

@@ -33,6 +33,7 @@
 #cmakedefine01 INNOEXTRACT_HAVE_STD_UNIQUE_PTR
 
 // Optional dependencies
+#cmakedefine01 INNOEXTRACT_HAVE_ARC4
 #cmakedefine01 INNOEXTRACT_HAVE_LZMA
 #cmakedefine01 INNOEXTRACT_HAVE_ICONV
 #cmakedefine01 INNOEXTRACT_HAVE_WIN32_CONV

src/crypto/arc4.cpp

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2018 Daniel Scharrer
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the author(s) be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ */
+
+#include "crypto/arc4.hpp"
+
+#include <algorithm>
+
+#include "util/endian.hpp"
+
+namespace crypto {
+
+void arc4::init(const char * key, size_t length) {
+	
+	a = b = 0;
+	
+	for(size_t i = 0; i < sizeof(state); i++){
+		state[i] = (unsigned char)i;
+	}
+	
+	size_t j = 0;
+	for(size_t i = 0; i < sizeof(state); i++) {
+		j = (j + state[i] +  (unsigned char)key[i % length]) % sizeof(state);
+		std::swap(state[i], state[j]);
+	}
+	
+}
+
+void arc4::update() {
+	
+	a = (a + 1) % sizeof(state);
+	b = (b + state[a]) % sizeof(state);
+	
+	std::swap(state[a], state[b]);
+	
+}
+
+void arc4::discard(size_t length) {
+	
+	for(size_t i = 0; i < length; i++) {
+		update();
+	}
+	
+}
+
+void arc4::crypt(const char * in, char * out, size_t length) {
+	
+	for(size_t i = 0; i < length; i++) {
+		update();
+		out[i] = char(state[size_t(state[a] + state[b]) % sizeof(state)] ^ (unsigned char)in[i]);
+	}
+	
+}
+
+} // namespace crypto

src/crypto/arc4.hpp

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2018 Daniel Scharrer
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the author(s) be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ */
+
+/*!
+ * \file
+ *
+ * Alledged RC4 en-/decryption routines.
+ */
+#ifndef INNOEXTRACT_CRYPTO_ARC4_HPP
+#define INNOEXTRACT_CRYPTO_ARC4_HPP
+
+#include <stddef.h>
+
+#include <boost/cstdint.hpp>
+
+#include "configure.hpp"
+
+#if INNOEXTRACT_HAVE_ARC4
+
+namespace crypto {
+
+//! Alledged RC4 en-/decryption calculation
+struct arc4 {
+	
+	void init(const char * key, size_t length);
+	
+	void discard(size_t length);
+	
+	void crypt(const char * in, char * out, size_t length);
+	
+private:
+	
+	void update();
+	
+	unsigned char state[256];
+	size_t a, b;
+	
+};
+
+} // namespace crypto
+
+#endif // INNOEXTRACT_HAVE_ARC4
+
+#endif // INNOEXTRACT_CRYPTO_ARC4_HPP
+