Workshop o mikrokontrolérech na SKSP 2024.
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/*
* HMAC-SHA1 Message Authentication Code (RFC 2202)
*
* (c) 2008--2009 Martin Mares <mj@ucw.cz>
*
* This software may be freely distributed and used according to the terms
* of the GNU Lesser General Public License.
*/
#include <ucw/lib.h>
#include <ucw/sha1.h>
#include <string.h>
void
sha1_hmac_init(sha1_hmac_context *hd, const byte *key, uint keylen)
{
byte keybuf[SHA1_BLOCK_SIZE], buf[SHA1_BLOCK_SIZE];
// Hash the key if necessary
if (keylen <= SHA1_BLOCK_SIZE)
{
memcpy(keybuf, key, keylen);
bzero(keybuf + keylen, SHA1_BLOCK_SIZE - keylen);
}
else
{
sha1_hash_buffer(keybuf, key, keylen);
bzero(keybuf + SHA1_SIZE, SHA1_BLOCK_SIZE - SHA1_SIZE);
}
// Initialize the inner digest
sha1_init(&hd->ictx);
for (int i=0; i < SHA1_BLOCK_SIZE; i++)
buf[i] = keybuf[i] ^ 0x36;
sha1_update(&hd->ictx, buf, SHA1_BLOCK_SIZE);
// Initialize the outer digest
sha1_init(&hd->octx);
for (int i=0; i < SHA1_BLOCK_SIZE; i++)
buf[i] = keybuf[i] ^ 0x5c;
sha1_update(&hd->octx, buf, SHA1_BLOCK_SIZE);
}
void
sha1_hmac_update(sha1_hmac_context *hd, const byte *data, uint datalen)
{
// Just update the inner digest
sha1_update(&hd->ictx, data, datalen);
}
byte *sha1_hmac_final(sha1_hmac_context *hd)
{
// Finish the inner digest
byte *isha = sha1_final(&hd->ictx);
// Finish the outer digest
sha1_update(&hd->octx, isha, SHA1_SIZE);
return sha1_final(&hd->octx);
}
void
sha1_hmac(byte *outbuf, const byte *key, uint keylen, const byte *data, uint datalen)
{
sha1_hmac_context hd;
sha1_hmac_init(&hd, key, keylen);
sha1_hmac_update(&hd, data, datalen);
byte *osha = sha1_hmac_final(&hd);
memcpy(outbuf, osha, SHA1_SIZE);
}
#ifdef TEST
#include <stdio.h>
#include <ucw/string.h>
static uint rd(char *dest)
{
char buf[1024];
if (!fgets(buf, sizeof(buf), stdin))
die("fgets()");
*strchr(buf, '\n') = 0;
if (buf[0] == '0' && buf[1] == 'x')
{
const char *e = hex_to_mem(dest, buf+2, 1024, 0);
ASSERT(!*e);
return (e-buf-2)/2;
}
else
{
strcpy(dest, buf);
return strlen(dest);
}
}
int main(void)
{
char key[1024], data[1024];
byte hmac[SHA1_SIZE];
uint kl = rd(key);
uint dl = rd(data);
sha1_hmac(hmac, key, kl, data, dl);
mem_to_hex(data, hmac, SHA1_SIZE, 0);
puts(data);
return 0;
}
#endif