hmac_md5.c

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#include "global.h"
#include "md5.h"
#include "str.h"
#include "byte.h"

 
void hmac_md5(char *text,int text_len,char * key,int key_len,char *digest)
{
   MD5_CTX context;
   unsigned char k_ipad[65];    /* inner padding - key XORd with ipad */
   unsigned char k_opad[65];    /* outer padding - key XORd with opad */
   char tk[16];
   int i;
 
   if (key_len > 64) {
     MD5Init(&context);
     MD5Update(&context,(unsigned char *) key,key_len);
     MD5Final((unsigned char *) tk,&context);
     key = tk;
     key_len = 16;
   }
 
   byte_zero((char *)k_ipad,sizeof(k_ipad));
   byte_zero((char *)k_opad,sizeof(k_opad));
   byte_copy((char *)k_ipad,key_len,key);
   byte_copy((char *)k_opad,key_len,key);
 
   for (i = 0; i < 64; i++) {
      k_ipad[i] ^= 0x36;
      k_opad[i] ^= 0x5c;
   }
 
   MD5Init(&context);                                      /* init context for 1st pass */
   MD5Update(&context,k_ipad,64);                          /* start with inner pad */
   MD5Update(&context,(unsigned char *) text,text_len);    /* then text of datagram */
   MD5Final((unsigned char *) digest,&context);            /* finish up 1st pass */
 
   MD5Init(&context);                                      /* init context for 2nd pass */
   MD5Update(&context,k_opad,64);                          /* start with outer pad */
   MD5Update(&context,(unsigned char *) digest,16);        /* then results of 1st hash */
   MD5Final((unsigned char *) digest,&context);            /* finish up 2nd pass */
}