sys/src/libsec/port/desCBC.c

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