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发表于 2012-4-1 14:44:41
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1.the format of encrypted file
> > > can_v1_5/can_tl_bsp.vhd as an example.
> > > a)the first 8 bytes XlxV38EB is version code
> > > b)the first 8bytes of line2 is the length of the ciphertext.，it means
> > > that the next segment of ciphertext is after 3230H
> > > c)from 18h bytes is ciphertext which is made by the Zlib compress then
> > > DES encrypted.
> > > ----------------------
> > > 00000000h: 58 6C 78 56 33 38 45 42 20 20 20 20 66 61 30 30 ;
> > > XlxV38EB fa00
> > > 00000010h: 20 20 20 20 33 32 33 30 39 1E 5F B2 14 42 33 C1 ;
> > > 32309._?B3?
> > > 00000020h: 82 40 EA 28 A0 8D 8C E9 8B 75 8B 0E 7C C4 6E BA ;
> > > ?@??????u?|?n?
> > > 00000030h: B0 2F 08 7C 51 C0 B0 45 01 D5 BD B8 73 A1 A1 09 ; ?.|Q腊E.战?s
> > > .
> > > 00000040h: 71 2A 81 FA A7 9E 99 CA 9C BE 15 7C 44 D1 E9 C1 ; q*????????.|D
> > > 验?
> > > 00000050h: D5 A8 81 9B 1E 3A 19 47 4A 49 AA 87 1C E2 E2 46 ; 炸??.:.GJI??.
> > > 忖F
> > > 。。。。。。。。。。。。。。
> > > 。。。。。。。。。。。。。。。
> > > 00003220h: 0F DD 81 68 7A B1 C5 92 FD 7C 77 FB 73 96 46 82 ; .??hz迸??|w?s
> > > ?F?
> > > 00003230h: A4 63 0B F1 64 17 1D D5 18 19 B2 E8 1D 23 DF 0F ; ?c.?d..?.
> > > 茶.#?
> > > 00003240h: 24 11 C2 D4 D0 90 38 7D 58 6C 78 56 33 38 45 42 ; $.略??8}
> > > XlxV38EB
> > > 00003250h: 20 20 20 20 36 38 64 37 20 20 20 20 31 34 66 63 ;
> > > 68d7 14fc
> > > 00003260h: D5 F9 A3 5C F9 7D D7 4A 72 09 19 86 03 62 C4 2C ; 争?\?}?Jr..?
> > > b?
> > > 00003270h: FE DC 28 58 7E 1F 91 2F 0F CD A8 DB 8E A0 FF 37 ; ??(X~.?.通???
> > > 7
> > > 00003280h: 01 F4 62 07 CE BA 6E 3C BB 67 4C B0 D9 E8 AE E3 ; .?b.魏n<?gL百
> > > 璁
>
> > > 2.how to decrypt
> > > 1)With DES, each 8bytes block is encrypted under same DES key。
> > > if the ciphertext can't be divided evenly,don't process these left
> > > bytes。
> > > 2)the DES key of Xilinx IPCOREis same 8f c2 d3 a0 XX XX XX XX，which
> > > be recover by below couple dates。
> > > ciphertext 39 1E 5F B2 14 42 33 C1
> > > plaintext75 41 73 32 dd 59 ea 0c
>
> > > 3)XOR with the initial date 0d 9b 9e 4f b6 2a f1 37
> > > 4)then we get 78 73 32 dd xx xx xx xx
> > > 5)replace the initial XOR date by this 8 bytes39 1E 5F B2 14 42 33 C1，
> > > 6)go to 2
> > > 7）combine to a file
>
> > > 3.download ZLIB fromhttp://www.zlib.net/
> > > 1）call the unpress function inf(file1,file2);
> > > 2）the we got the source code file2 as below:
>
> > > -- $Id: can_tl_bsp.vhd,v 1.1.2.2 2007/05/28 13:39:29 snori Exp $
> > > -------------------------------------------------------------------------------
> > > -------------------------------------------------------------------------------
> > > -------------------------------------------------------------------------------
> > > -- Copyright(C) 2007 by Xilinx, Inc. All rights reserved.
> > > -- This text/file contains proprietary, confidential
> > > -- information of Xilinx, Inc., is distributed under
> > > -- license from Xilinx, Inc., and may be used, copied
> > > -- and/or disclosed only pursuant to the terms of a valid
> > > -- license agreement with Xilinx, Inc. Xilinx hereby
>
> > > 。。。。。。。。。。。。。。。
> > > 。。。。。。。。。。。。。。。
>
> > > smcomb: process(state, RXE_COUNTER_I, SM_STUFFBIT_PD,SM_STUFFBIT,
> > > BSOFF_COUNTER_I, TEC_INC8_I, EMU_TEC_BOFF_LT1,
> > > EMU_REC_ERRACT,BTL_RXBIT,IC_MSR_LBACK,IC_MSR_SLEEP,
> > > TX_HPB_EMPTY,TX_FIFO_EMPTY)
> > > begin
>
> > > -- Enable Stuff Module when State = ID and after the 3rd bit
> > > -- after SOF been received.
> > > if (state = ID and RXE_COUNTER_I = C3) then
> > > RXE_SM_EN <= '1';
> > > else
> > > RXE_SM_EN <= '0';
> > > end if;
>
> > > -- Reset CRC when State = EOF
> > > -- When RXE_CRC_RST = '1', the CRC register is reset.
> > > -- Reset when State = EOF and RXE_COUNTER_I = CO
> > > -- (After ACK field)
> > > -- Reset when in ERRACT and ERRPASS and RXE_COUNTER_I = C0. It is
> > > possible
> > > -- that Reset could be asserted for multiple cycles.
>
> > > if ((state = EOF and RXE_COUNTER_I = C0) or
> > > ((state = ERRACT or state = ERRPASS) and RXE_COUNTER_I = C1)
> > > or state = BOFF) then
> > > RXE_CRC_RST <= '1';
> > > else
> > > RXE_CRC_RST <= '0';
> > > end if;
>
> > this is COMMON knowledge for long time already
> > i wrote a zlib based encoder many many years ago for a study 
>
> > but thank you for making it public-public!
>
> > Antti
>
> Hello Antti,
>
> can you point me to your encoder please ?
>
> Thanks!
>
> /HB
Hi HB, it's easy to make a decoder like below
//Initial XOR seeds
xorseed={0x0d,0x9b,0x9e,0x4f,0xb6,0x2a,0xf1,0x37};
....
do
{
//read and process 8 bytes every time
unRead = fread(crypt, SIZE, 8, encryptfile);
//Call DES decrypt function
DES(&crypt[i*SIZE],&decrypt[i*SIZE], 8, deskey, DECRYPT);
// decrypted results XOR with the initial XOR seeds
decrypt[i*SIZE]^=xorseed[0];
decrypt[i*SIZE+1]^=xorseed[1];
decrypt[i*SIZE+2]^=xorseed[2];
decrypt[i*SIZE+3]^=xorseed[3];
decrypt[i*SIZE+4]^=xorseed[4];
decrypt[i*SIZE+5]^=xorseed[5];
decrypt[i*SIZE+6]^=xorseed[6];
decrypt[i*SIZE+7]^=xorseed[7];
//Update the XOR seeds by last encrypted 8 bytes
xorseed[0]=crypt[i*SIZE];
xorseed[1]=crypt[i*SIZE+1];
xorseed[2]=crypt[i*SIZE+2];
xorseed[3]=crypt[i*SIZE+3];
xorseed[4]=crypt[i*SIZE+4];
xorseed[5]=crypt[i*SIZE+5];
xorseed[6]=crypt[i*SIZE+6];
xorseed[7]=crypt[i*SIZE+7];
//write to a file or keep in memory
fwrite(decrypt, SIZE, unRead, compressfile);
} (!feof(cryptfile) && unRead != 0);
..........
//Call ZLIB uncompress
inf(compressfile,plaintextfile); |
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