mirror of
https://github.com/MacPaw/XADMaster.git
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85 lines
2.1 KiB
Objective-C
85 lines
2.1 KiB
Objective-C
/*
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* XADZipCryptHandle.m
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*
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* Copyright (c) 2017-present, MacPaw Inc. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#import "XADZipCryptHandle.h"
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#import "XADException.h"
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#import "CRC.h"
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@implementation XADZipCryptHandle
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static void UpdateKeys(XADZipCryptHandle *self,uint8_t b)
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{
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self->key0=XADCRC(self->key0,b,XADCRCTable_edb88320);
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self->key1+=self->key0&0xff;
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self->key1=self->key1*134775813+1;
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self->key2=XADCRC(self->key2,self->key1>>24,XADCRCTable_edb88320);
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}
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static uint8_t DecryptByte(XADZipCryptHandle *self)
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{
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uint16_t temp=self->key2|2;
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return (temp*(temp^1))>>8;
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}
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length password:(NSData *)passdata testByte:(uint8_t)testbyte
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{
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if((self=[super initWithInputBufferForHandle:handle length:length-12]))
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{
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password=[passdata retain];
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test=testbyte;
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}
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return self;
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}
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-(void)dealloc
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{
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[password release];
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[super dealloc];
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}
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-(void)resetByteStream
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{
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key0=305419896;
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key1=591751049;
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key2=878082192;
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int passlength=[password length];
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const uint8_t *passbytes=[password bytes];
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for(int i=0;i<passlength;i++) UpdateKeys(self,passbytes[i]);
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for(int i=0;i<12;i++)
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{
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uint8_t b=CSInputNextByte(input)^DecryptByte(self);
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UpdateKeys(self,b);
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if(i==11&&b!=test) [XADException raisePasswordException];
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}
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}
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-(uint8_t)produceByteAtOffset:(off_t)pos
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{
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uint8_t b=CSInputNextByte(input)^DecryptByte(self);
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//NSLog(@"%02x",b);
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UpdateKeys(self,b);
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return b;
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}
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@end
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