83 lines
2.4 KiB
C
83 lines
2.4 KiB
C
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/****************************************************************
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* *
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* Copyright 2001, 2007 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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/* la_encrypt.c : for given encryption function number, and an input sequence of bytes,
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the program computes the checksum of the sequence.
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used in : la_create.c,lp_licensed.c,lm_verify
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*/
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#include "mdef.h"
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#include "la_encrypt.h"
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static void la_encrypt_table (uint4 poly, uint4 tbl[]);
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static uint4 la_encrypt_value (
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uint4 tbl[], /* polynomial coefficients */
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uint4 cs, /* checksum initial value */
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unsigned char *c, /* string to compute the check sum for */
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int len); /* string length */
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bool la_encrypt (
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short n , /* encryption function number */
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char *q , /* input sequence */
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int len, /* sequence length */
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uint4 bcs[]) /* result, binary form */
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{
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static uint4 poly0[10] = {0xEDB88320, 0xA001A001, 0x00008408, 0x00000000, 0xA001A001, 1, 1, 1, 1, 1};
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static uint4 init0[10] = {0xFFFFFFFF, 0x00000000, 0x0000FFFF, 0xFFFFFFFF, 0x00000000, 0, 0, 0, 0, 0};
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static uint4 poly1[10] = {0xA001A001, 0x00008408, 0xEDB88320, 0xEDB88320, 0x0000A001, 1, 1, 1, 1, 1};
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static uint4 init1[10] = {0x00000000, 0x0000FFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0, 0, 0, 0, 0};
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uint4 crctbl[16];
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if (n<5)
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{
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la_encrypt_table(poly0[n],crctbl) ;
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bcs[0] = la_encrypt_value(crctbl,init0[n],(uchar_ptr_t)q,len) ;
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la_encrypt_table(poly1[n],crctbl) ;
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bcs[1] = la_encrypt_value(crctbl,init1[n],(uchar_ptr_t)q,len) ;
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}
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return n<5 ;
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}
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static void la_encrypt_table (uint4 poly, uint4 tbl[])
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{
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uint4 k, t, x;
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int i;
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for ( k= 0 ; k!=16 ; k++ )
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{
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t= k ;
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for ( i= 0 ; i!=4 ; i++ )
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{
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x= t & 1 ;
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t= t>>1 ;
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if (x==1) t ^= poly ;
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}
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tbl[k]= t ;
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}
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}
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static uint4 la_encrypt_value (
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uint4 tbl[], /* polynomial coefficients */
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uint4 cs, /* checksum initial value */
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unsigned char *c, /* string to compute the check sum for */
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int len) /* string length */
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{
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while ( len!=0 )
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{
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cs ^= (int4)*c ; /* least signif. byte of cs differred with *c */
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cs = ( cs >> 4 ) ^ tbl[cs & 0xF] ;
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cs = ( cs >> 4 ) ^ tbl[cs & 0xF] ;
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c++ ; len-- ;
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}
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return cs ;
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}
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