hmac.c

   1 #include "quakedef.h"
   2 #include "hmac.h"
   3
   4 qboolean hmac(
   5         hashfunc_t hfunc, int hlen, int hblock,
   6         unsigned char *out,
   7         unsigned char *in, int n,
   8         unsigned char *key, int k
   9 )
  10 {
  11         static unsigned char hashbuf[32];
  12         static unsigned char k_xor_ipad[128];
  13         static unsigned char k_xor_opad[128];
  14         static unsigned char catbuf[4096];
  15         int i;
  16
  17         if(sizeof(hashbuf) < (size_t) hlen)
  18                 return false;
  19         if(sizeof(k_xor_ipad) < (size_t) hblock)
  20                 return false;
  21         if(sizeof(k_xor_ipad) < (size_t) hlen)
  22                 return false;
  23         if(sizeof(catbuf) < (size_t) hblock + (size_t) hlen)
  24                 return false;
  25         if(sizeof(catbuf) < (size_t) hblock + (size_t) n)
  26                 return false;
  27
  28         if(k > hblock)
  29         {
  30                 // hash the key if it is too long
  31                 hfunc(k_xor_opad, key, k);
  32                 key = k_xor_opad;
  33                 k = hlen;
  34         }
  35
  36         if(k < hblock)
  37         {
  38                 // zero pad the key if it is too short
  39                 if(key != k_xor_opad)
  40                         memcpy(k_xor_opad, key, k);
  41                 for(i = k; i < hblock; ++i)
  42                         k_xor_opad[i] = 0;
  43                 key = k_xor_opad;
  44                 k = hblock;
  45         }
  46
  47         for(i = 0; i < hblock; ++i)
  48         {
  49                 k_xor_ipad[i] = key[i] ^ 0x36;
  50                 k_xor_opad[i] = key[i] ^ 0x5c;
  51         }
  52
  53         memcpy(catbuf, k_xor_ipad, hblock);
  54         memcpy(catbuf + hblock, in, n);
  55         hfunc(hashbuf, catbuf, hblock + n);
  56         memcpy(catbuf, k_xor_opad, hblock);
  57         memcpy(catbuf + hblock, hashbuf, hlen);
  58         hfunc(out, catbuf, hblock + hlen);
  59         return true;
  60 }