mdw@git.distorted.org.uk Git - ezmlm/blob - cookie.c

   1 #include "cookie.h"
   2 #include "str.h"
   3 #include "uint32.h"
   4 #include "surfpcs.h"
   5
   6 void cookie(hash,key,keylen,date,addr,action)
   7 char *hash;
   8 char *key;
   9 unsigned int keylen;
  10 char *date;
  11 char *addr;
  12 char *action;
  13 {
  14   surfpcs s;
  15   uint32 seed[32];
  16   unsigned char out[32];
  17   int i;
  18   int j;
  19
  20 /*
  21 step 1: create seed from key. note that this doesn't have to be
  22 cryptographic; it simply has to avoid destroying the user's entropy.
  23 if speed turns out to be a problem, switch to a CRC.
  24 */
  25   for (i = 0;i < 32;++i) seed[i] = 0;
  26   for (j = 0;j < 4;++j) {
  27     surfpcs_init(&s,seed);
  28     surfpcs_add(&s,key,keylen);
  29     surfpcs_out(&s,out);
  30     for (i = 0;i < 32;++i) seed[i] = (seed[i] << 8) + out[i];
  31   }
  32
  33 /*
  34 step 2: apply SURF.
  35 */
  36   surfpcs_init(&s,seed);
  37   surfpcs_add(&s,date,str_len(date) + 1);
  38   surfpcs_add(&s,addr,str_len(addr) + 1);
  39   surfpcs_add(&s,action,1);
  40   surfpcs_out(&s,out);
  41
  42 /*
  43 step 3: extract a readable cookie from the SURF output.
  44 */
  45   for (i = 0;i < 20;++i)
  46     hash[i] = 'a' + (out[i] & 15);
  47 }