tdesCBC.c - plan9port - [fork] Plan 9 from user space
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       ---
       tdesCBC.c (1097B)
       ---
            1 #include "os.h"
            2 #include <mp.h>
            3 #include <libsec.h>
            4 
            5 /* Because of the way that non multiple of 8 */
            6 /* buffers are handled, the decryptor must */
            7 /* be fed buffers of the same size as the */
            8 /* encryptor */
            9 
           10 
           11 /* If the length is not a multiple of 8, I encrypt */
           12 /* the overflow to be compatible with lacy's cryptlib */
           13 void
           14 desCBCencrypt(uchar *p, int len, DESstate *s)
           15 {
           16         uchar *p2, *ip, *eip;
           17 
           18         for(; len >= 8; len -= 8){
           19                 p2 = p;
           20                 ip = s->ivec;
           21                 for(eip = ip+8; ip < eip; )
           22                         *p2++ ^= *ip++;
           23                 block_cipher(s->expanded, p, 0);
           24                 memmove(s->ivec, p, 8);
           25                 p += 8;
           26         }
           27 
           28         if(len > 0){
           29                 ip = s->ivec;
           30                 block_cipher(s->expanded, ip, 0);
           31                 for(eip = ip+len; ip < eip; )
           32                         *p++ ^= *ip++;
           33         }
           34 }
           35 
           36 void
           37 desCBCdecrypt(uchar *p, int len, DESstate *s)
           38 {
           39         uchar *ip, *eip, *tp;
           40         uchar tmp[8];
           41 
           42         for(; len >= 8; len -= 8){
           43                 memmove(tmp, p, 8);
           44                 block_cipher(s->expanded, p, 1);
           45                 tp = tmp;
           46                 ip = s->ivec;
           47                 for(eip = ip+8; ip < eip; ){
           48                         *p++ ^= *ip;
           49                         *ip++ = *tp++;
           50                 }
           51         }
           52 
           53         if(len > 0){
           54                 ip = s->ivec;
           55                 block_cipher(s->expanded, ip, 0);
           56                 for(eip = ip+len; ip < eip; )
           57                         *p++ ^= *ip++;
           58         }
           59 }