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/* From RFC2104 */
/*
** Function: hmac_md5
*/
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#include "compat.h"
#include "md5.h"
/*
* unsigned char* text; pointer to data stream/
* int text_len; length of data stream
* unsigned char* key; pointer to authentication key
* int key_len; length of authentication key
* caddr_t digest; caller digest to be filled in
*/
void
smb2_hmac_md5(unsigned char *text, int text_len, unsigned char *key, unsigned int key_len,
unsigned char *digest)
{
struct MD5Context 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) {
struct MD5Context 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
* 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);
memmove(k_ipad, key, key_len);
memmove(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 */
}
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