lib/hmac.c

   1 #include "hmac.h"
   2 #include <string.h>
   3 #include <ctype.h>
   4
   5 void hmacsha256_init(hmacsha256 *c, unsigned char *key, int keylen) {
   6   unsigned char realkey[64], outerkey[64], innerkey[64];
   7   SHA256_CTX keyc;
   8   int i;
   9
  10   memset(realkey, 0, sizeof(realkey));
  11   if(keylen > 64) {
  12     SHA256_Init(&keyc);
  13     SHA256_Update(&keyc, key, keylen);
  14     SHA256_Final(realkey, &keyc);
  15     keylen = 32;
  16   } else {
  17     memcpy(realkey, key, keylen);
  18   }
  19
  20   /* abusing the cache here, if we do sha256 in between that'll erase it */
  21   for(i=0;i<64;i++) {
  22     int r = realkey[i];
  23     innerkey[i] = r ^ 0x36;
  24     outerkey[i] = r ^ 0x5c;
  25   }
  26
  27   SHA256_Init(&c->outer);
  28   SHA256_Init(&c->inner);
  29   SHA256_Update(&c->outer, outerkey, 64);
  30   SHA256_Update(&c->inner, innerkey, 64);
  31 }
  32
  33 void hmacsha256_update(hmacsha256 *c, unsigned char *message, int messagelen) {
  34   SHA256_Update(&c->inner, message, messagelen);
  35 }
  36
  37 void hmacsha256_final(hmacsha256 *c, unsigned char *digest) {
  38   SHA256_Final(digest, &c->inner);
  39   SHA256_Update(&c->outer, digest, 32);
  40   SHA256_Final(digest, &c->outer);
  41 }
  42
  43 void hmacsha1_init(hmacsha1 *c, unsigned char *key, int keylen) {
  44   unsigned char realkey[64], outerkey[64], innerkey[64];
  45   SHA1_CTX keyc;
  46   int i;
  47
  48   memset(realkey, 0, sizeof(realkey));
  49   if(keylen > 64) {
  50     SHA1Init(&keyc);
  51     SHA1Update(&keyc, key, keylen);
  52     SHA1Final(realkey, &keyc);
  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 void hmacmd5_init(hmacmd5 *c, unsigned char *key, int keylen) {
  81   unsigned char realkey[64], outerkey[64], innerkey[64];
  82   MD5Context keyc;
  83   int i;
  84
  85   memset(realkey, 0, sizeof(realkey));
  86   if(keylen > 64) {
  87     MD5Init(&keyc);
  88     MD5Update(&keyc, key, keylen);
  89     MD5Final(realkey, &keyc);
  90   } else {
  91     memcpy(realkey, key, keylen);
  92   }
  93
  94   /* abusing the cache here, if we do sha1 in between that'll erase it */
  95   for(i=0;i<64;i++) {
  96     int r = realkey[i];
  97     innerkey[i] = r ^ 0x36;
  98     outerkey[i] = r ^ 0x5c;
  99   }
 100
 101   MD5Init(&c->outer);
 102   MD5Init(&c->inner);
 103   MD5Update(&c->outer, outerkey, 64);
 104   MD5Update(&c->inner, innerkey, 64);
 105 }
 106
 107 void hmacmd5_update(hmacmd5 *c, unsigned char *message, int messagelen) {
 108   MD5Update(&c->inner, message, messagelen);
 109 }
 110
 111 void hmacmd5_final(hmacmd5 *c, unsigned char *digest) {
 112   MD5Final(digest, &c->inner);
 113   MD5Update(&c->outer, digest, 16);
 114   MD5Final(digest, &c->outer);
 115 }
 116
 117 static const char *hexdigits = "0123456789abcdef";
 118
 119 char *hmac_printhex(unsigned char *data, char *out, size_t len) {
 120   size_t i;
 121   unsigned char *o = (unsigned char *)out;
 122
 123   for(i=0;i<len;i++) {
 124     *o++ = hexdigits[(*data & 0xf0) >> 4];
 125     *o++ = hexdigits[*data & 0x0f];
 126     data++;
 127   }
 128
 129   *o = '\0';
 130   return out;
 131 }
 132
 133 int hmac_strcmp(const char *a, const char *b) {
 134   int result = 1;
 135
 136   if(!a || !b)
 137     return 1;
 138
 139   if(strlen(a) != strlen(b))
 140     return 1;
 141
 142   while(*a)
 143     result&=(tolower(*a++) == tolower(*b++));
 144
 145   return !result;
 146 }
 147