/* * hmac.c	For the sake of illustration we provide the following *		sample code for the implementation of HMAC-MD5 as well *		as some corresponding test vectors (the code is based *		on MD5 code as described in [MD5]). * *   This library is free software; you can redistribute it and/or *   modify it under the terms of the GNU Lesser General Public *   License as published by the Free Software Foundation; either *   version 2.1 of the License, or (at your option) any later version. * *   This library is distributed in the hope that it will be useful, *   but WITHOUT ANY WARRANTY; without even the implied warranty of *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *   Lesser General Public License for more details. * *   You should have received a copy of the GNU Lesser General Public *   License along with this library; if not, write to the Free Software *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA * * Copyright 2000  The FreeRADIUS server project *//*** Function: hmac_md5*/#include <string.h>#include "md5.h"#include "libradius.h"/*unsigned char*  text;                pointer to data streamint             text_len;            length of data streamunsigned char*  key;                 pointer to authentication keyint             key_len;             length of authentication keyunsigned char*  digest;              caller digest to be filled in*/voidlrad_hmac_md5(const unsigned char *text, int text_len,	      const unsigned char *key, int key_len,	      unsigned 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                                      */        unsigned char tk[16];        int i;        /* if key is longer than 64 bytes reset it to key=MD5(key) */        if (key_len > 64) {                MD5_CTX      tctx;                MD5Init(&tctx);                MD5Update(&tctx, key, key_len);                MD5Final(tk, &tctx);                key = tk;                key_len = 16;        }        /*         * the HMAC_MD5 transform looks like:         *         * MD5(K XOR opad, MD5(K XOR ipad, text))         *         * where K is an n byte key         * ipad is the byte 0x36 repeated 64 times         * opad is the byte 0x5c repeated 64 times         * and text is the data being protected         */        /* start out by storing key in pads */        memset( k_ipad, 0, sizeof(k_ipad));        memset( k_opad, 0, sizeof(k_opad));        memcpy( k_ipad, key, key_len);        memcpy( k_opad, key, key_len);        /* XOR key with ipad and opad values */        for (i = 0; i < 64; i++) {                k_ipad[i] ^= 0x36;                k_opad[i] ^= 0x5c;        }        /*         * perform inner MD5         */        MD5Init(&context);                   /* init context for 1st                                              * pass */        MD5Update(&context, k_ipad, 64);      /* start with inner pad */        MD5Update(&context, text, text_len); /* then text of datagram */        MD5Final(digest, &context);          /* finish up 1st pass */        /*         * perform outer MD5         */        MD5Init(&context);                   /* init context for 2nd                                              * pass */        MD5Update(&context, k_opad, 64);     /* start with outer pad */        MD5Update(&context, digest, 16);     /* then results of 1st                                              * hash */        MD5Final(digest, &context);          /* finish up 2nd pass */}/*Test Vectors (Trailing '\0' of a character string not included in test):  key =         0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b  key_len =     16 bytes  data =        "Hi There"  data_len =    8  bytes  digest =      0x9294727a3638bb1c13f48ef8158bfc9d  key =         "Jefe"  data =        "what do ya want for nothing?"  data_len =    28 bytes  digest =      0x750c783e6ab0b503eaa86e310a5db738  key =         0xAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA  key_len       16 bytes  data =        0xDDDDDDDDDDDDDDDDDDDD...                ..DDDDDDDDDDDDDDDDDDDD...                ..DDDDDDDDDDDDDDDDDDDD...                ..DDDDDDDDDDDDDDDDDDDD...                ..DDDDDDDDDDDDDDDDDDDD  data_len =    50 bytes  digest =      0x56be34521d144c88dbb8c733f0e8b3f6*/#ifdef TESTING/* *  cc -DTESTING -I ../include/ hmac.c md5.c -o hmac * *  ./hmac Jefe "what do ya want for nothing?" */#include <stdio.h>#include <stdlib.h>int main(int argc, char **argv){  unsigned char digest[16];  char *key;  int key_len;  char *text;  int text_len;  int i;  key = argv[1];  key_len = strlen(key);  text = argv[2];  text_len = strlen(text);  lrad_hmac_md5(text, text_len, key, key_len, digest);  for (i = 0; i < 16; i++) {    printf("%02x", digest[i]);  }  printf("\n");  exit(0);  return 0;}#endif