lib/hmac.c

   1 #include "hmac.h"
   2 #include <string.h>
   3
   4 void hmacsha256_init(hmacsha256 *c, unsigned char *key, int keylen) {
   5   unsigned char realkey[64], outerkey[64], innerkey[64];
   6   SHA256_CTX keyc;
   7   int i;
   8
   9   memset(realkey, 0, sizeof(realkey));
  10   if(keylen > 64) {
  11     SHA256_Init(&keyc);
  12     SHA256_Update(&keyc, key, keylen);
  13     SHA256_Final(realkey, &keyc);
  14     keylen = 32;
  15   } else {
  16     memcpy(realkey, key, keylen);
  17   }
  18
  19   /* abusing the cache here, if we do sha256 in between that'll erase it */
  20   for(i=0;i<64;i++) {
  21     int r = realkey[i];
  22     innerkey[i] = r ^ 0x36;
  23     outerkey[i] = r ^ 0x5c;
  24   }
  25
  26   SHA256_Init(&c->outer);
  27   SHA256_Init(&c->inner);
  28   SHA256_Update(&c->outer, outerkey, 64);
  29   SHA256_Update(&c->inner, innerkey, 64);
  30 }
  31
  32 void hmacsha256_update(hmacsha256 *c, unsigned char *message, int messagelen) {
  33   SHA256_Update(&c->inner, message, messagelen);
  34 }
  35
  36 void hmacsha256_final(hmacsha256 *c, unsigned char *digest) {
  37   SHA256_Final(digest, &c->inner);
  38   SHA256_Update(&c->outer, digest, 32);
  39   SHA256_Final(digest, &c->outer);
  40 }
  41
  42 void hmacsha1_init(hmacsha1 *c, unsigned char *key, int keylen) {
  43   unsigned char realkey[64], outerkey[64], innerkey[64];
  44   SHA1_CTX keyc;
  45   int i;
  46
  47   memset(realkey, 0, sizeof(realkey));
  48   if(keylen > 64) {
  49     SHA1Init(&keyc);
  50     SHA1Update(&keyc, key, keylen);
  51     SHA1Final(realkey, &keyc);
  52     keylen = 20;
  53   } else {
  54     memcpy(realkey, key, keylen);
  55   }
  56
  57   /* abusing the cache here, if we do sha1 in between that'll erase it */
  58   for(i=0;i<64;i++) {
  59     int r = realkey[i];
  60     innerkey[i] = r ^ 0x36;
  61     outerkey[i] = r ^ 0x5c;
  62   }
  63
  64   SHA1Init(&c->outer);
  65   SHA1Init(&c->inner);
  66   SHA1Update(&c->outer, outerkey, 64);
  67   SHA1Update(&c->inner, innerkey, 64);
  68 }
  69
  70 void hmacsha1_update(hmacsha1 *c, unsigned char *message, int messagelen) {
  71   SHA1Update(&c->inner, message, messagelen);
  72 }
  73
  74 void hmacsha1_final(hmacsha1 *c, unsigned char *digest) {
  75   SHA1Final(digest, &c->inner);
  76   SHA1Update(&c->outer, digest, 20);
  77   SHA1Final(digest, &c->outer);
  78 }
  79
  80 static const char *hexdigits = "0123456789abcdef";
  81
  82 char *hmac_printhex(unsigned char *data, char *out, size_t len) {
  83   size_t i;
  84   char *o = out;
  85
  86   for(i=0;i<len;i++) {
  87     *o++ = hexdigits[(*data & 0xf0) >> 4];
  88     *o++ = hexdigits[*data & 0x0f];
  89     data++;
  90   }
  91
  92   *o = '\0';
  93   return out;
  94 }