godot/core/io/file_access_encrypted.cpp

/*************************************************************************/
/*  file_access_encrypted.cpp                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
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/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/*************************************************************************/
#include "file_access_encrypted.h"
#include "aes256.h"
#include "md5.h"
#include "os/copymem.h"
#include "print_string.h"
#define COMP_MAGIC 0x43454447

#include "core/variant.h"
#include <stdio.h>

Error FileAccessEncrypted::open_and_parse(FileAccess *p_base,const Vector<uint8_t>& p_key,Mode p_mode) {

	//print_line("open and parse!");
	ERR_FAIL_COND_V(file!=NULL,ERR_ALREADY_IN_USE);
	ERR_FAIL_COND_V(p_key.size()!=32,ERR_INVALID_PARAMETER);

	pos=0;
	eofed=false;

	if (p_mode==MODE_WRITE_AES256) {

		data.clear();
		writing=true;
		file=p_base;
		mode=p_mode;
		key=p_key;

	} else if (p_mode==MODE_READ) {

		writing=false;
		key=p_key;
		uint32_t magic = p_base->get_32();
		print_line("MAGIC: "+itos(magic));
		ERR_FAIL_COND_V(magic!=COMP_MAGIC,ERR_FILE_UNRECOGNIZED);
		mode=Mode(p_base->get_32());
		ERR_FAIL_INDEX_V(mode,MODE_MAX,ERR_FILE_CORRUPT);
		ERR_FAIL_COND_V(mode==0,ERR_FILE_CORRUPT);
		print_line("MODE: "+itos(mode));
		unsigned char md5d[16];
		p_base->get_buffer(md5d,16);
		length=p_base->get_64();
		base=p_base->get_pos();
		ERR_FAIL_COND_V(p_base->get_len() < base+length, ERR_FILE_CORRUPT );
		int ds = length;
		if (ds % 16) {
			ds+=16-(ds % 16);
		}

		data.resize(ds);

		int blen = p_base->get_buffer(data.ptr(),ds);
		ERR_FAIL_COND_V(blen!=ds,ERR_FILE_CORRUPT);

		aes256_context ctx;
		aes256_init(&ctx,key.ptr());

		for(size_t i=0;i<ds;i+=16) {

			aes256_decrypt_ecb(&ctx,&data[i]);
		}

		aes256_done(&ctx);

		data.resize(length);

		MD5_CTX md5;
		MD5Init(&md5);
		MD5Update(&md5,data.ptr(),data.size());
		MD5Final(&md5);


		ERR_FAIL_COND_V(String::md5(md5.digest)!=String::md5(md5d),ERR_FILE_CORRUPT)		;


		file=p_base;
	}

	return OK;
}

Error FileAccessEncrypted::open_and_parse_password(FileAccess *p_base,const String& p_key,Mode p_mode){


	String cs = p_key.md5_text();
	ERR_FAIL_COND_V(cs.length()!=32,ERR_INVALID_PARAMETER);
	Vector<uint8_t> key;
	key.resize(32);
	for(int i=0;i<32;i++) {

		key[i]=cs[i];
	}

	return open_and_parse(p_base,key,p_mode);
}



Error FileAccessEncrypted::_open(const String& p_path, int p_mode_flags) {

	return OK;
}
void FileAccessEncrypted::close() {

	if (!file)
		return;

	if (writing) {

		Vector<uint8_t> compressed;
		size_t len = data.size();
		if (len % 16) {
			len+=16-(len % 16);
		}

		MD5_CTX md5;
		MD5Init(&md5);
		MD5Update(&md5,data.ptr(),data.size());
		MD5Final(&md5);

		compressed.resize(len);
		zeromem( compressed.ptr(), len );
		for(int i=0;i<data.size();i++) {
			compressed[i]=data[i];
		}

		aes256_context ctx;
		aes256_init(&ctx,key.ptr());

		for(size_t i=0;i<len;i+=16) {

			aes256_encrypt_ecb(&ctx,&compressed[i]);
		}

		aes256_done(&ctx);

		file->store_32(COMP_MAGIC);
		file->store_32(mode);


		file->store_buffer(md5.digest,16);
		file->store_64(data.size());

		file->store_buffer(compressed.ptr(),compressed.size());
		file->close();
		memdelete(file);
		file=NULL;
		data.clear();

	} else {

		file->close();
		memdelete(file);
		data.clear();
		file=NULL;
	}



}

bool FileAccessEncrypted::is_open() const{

	return file!=NULL;
}

void FileAccessEncrypted::seek(size_t p_position){

	if (p_position > (size_t)data.size())
		p_position=data.size();

	pos=p_position;
	eofed=false;

}


void FileAccessEncrypted::seek_end(int64_t p_position){

	seek( data.size() + p_position );
}
size_t FileAccessEncrypted::get_pos() const{

	return pos;
}
size_t FileAccessEncrypted::get_len() const{

	return data.size();
}

bool FileAccessEncrypted::eof_reached() const{

	return eofed;
}

uint8_t FileAccessEncrypted::get_8() const{

	ERR_FAIL_COND_V(writing,0);
	if (pos>=data.size()) {
		eofed=true;
		return 0;
	}

	uint8_t b = data[pos];
	pos++;
	return b;

}
int FileAccessEncrypted::get_buffer(uint8_t *p_dst, int p_length) const{

	ERR_FAIL_COND_V(writing,0);

	int to_copy=MIN(p_length,data.size()-pos);
	for(int i=0;i<to_copy;i++) {

		p_dst[i]=data[pos++];
	}

	if (to_copy<p_length) {
		eofed=true;
	}


	return to_copy;
}

Error FileAccessEncrypted::get_error() const{

	return eofed?ERR_FILE_EOF:OK;
}

void FileAccessEncrypted::store_buffer(const uint8_t *p_src,int p_length) {

	ERR_FAIL_COND(!writing);

	if (pos<data.size()) {

		for(int i=0;i<p_length;i++) {

			store_8(p_src[i]);
		}
	} else if (pos==data.size()) {

		data.resize(pos+p_length);
		for(int i=0;i<p_length;i++) {

			data[pos+i]=p_src[i];
		}
		pos+=p_length;
	}
}


void FileAccessEncrypted::store_8(uint8_t p_dest){

	ERR_FAIL_COND(!writing);

	if (pos<data.size()) {
		data[pos]=p_dest;
		pos++;
	} else if (pos==data.size()){
		data.push_back(p_dest);
		pos++;
	}
}

bool FileAccessEncrypted::file_exists(const String& p_name){

	FileAccess *fa = FileAccess::open(p_name,FileAccess::READ);
	if (!fa)
		return false;
	memdelete(fa);
	return true;
}

uint64_t FileAccessEncrypted::_get_modified_time(const String& p_file){


	return 0;
}

FileAccessEncrypted::FileAccessEncrypted() {

	file=NULL;
	pos=0;
	eofed=false;
	mode=MODE_MAX;
	writing=false;
}


FileAccessEncrypted::~FileAccessEncrypted() {

	if (file)
		close();
}