sys/src/libsec/port/desCBC.c

   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 }