mirror of
https://github.com/MacPaw/XADMaster.git
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79 lines
2 KiB
Objective-C
79 lines
2 KiB
Objective-C
/*
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* XADRAR15CryptHandle.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 "XADRAR15CryptHandle.h"
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#import "CRC.h"
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static inline uint16_t ror16(uint16_t val,int n) { return (val>>n)|(val<<(16-n)); }
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@implementation XADRAR15CryptHandle
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length password:(NSData *)passdata
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{
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if((self=[super initWithInputBufferForHandle:handle length:length]))
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{
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password=[passdata retain];
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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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int passlength=[password length];
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const uint8_t *passbytes=[password bytes];
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uint32_t crc=XADCalculateCRC(0xffffffff,passbytes,passlength,XADCRCTable_edb88320);
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key0=crc;
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key1=crc>>16;
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key2=key3=0;
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for(int i=0;i<passlength;i++)
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{
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uint8_t c=passbytes[i];
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key2^=c^XADCRCTable_edb88320[c];
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key3+=c+(XADCRCTable_edb88320[c]>>16);
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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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key0+=0x1234;
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key1^=XADCRCTable_edb88320[(key0>>1)&0xff];
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key2-=XADCRCTable_edb88320[(key0>>1)&0xff]>>16;
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key0^=key2;
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key3=ror16(key3&0xffff,1)^key1;
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key3=ror16(key3&0xffff,1);
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key0^=key3;
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if(CSInputAtEOF(input)) CSByteStreamEOF(self);
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return CSInputNextByte(input)^(key0>>8);
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}
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@end
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