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/*
* md5crypt - MD5 based authentication routines
*/
#include "ntp_types.h"
#include "ntp_string.h"
#include "md5.h"
#include "ntp_stdlib.h"
extern u_long cache_keyid;
extern char *cache_key;
extern int cache_keylen;
/*
* Stat counters, imported from data base module
*/
extern U_LONG authencryptions;
extern U_LONG authdecryptions;
extern U_LONG authkeyuncached;
extern U_LONG authnokey;
/*
* For our purposes an NTP packet looks like:
*
* a variable amount of encrypted data, multiple of 8 bytes, followed by:
* NOCRYPT_OCTETS worth of unencrypted data, followed by:
* BLOCK_OCTETS worth of ciphered checksum.
*/
#define NOCRYPT_OCTETS 4
#define BLOCK_OCTETS 16
#define NOCRYPT_LONGS ((NOCRYPT_OCTETS)/sizeof(U_LONG))
#define BLOCK_LONGS ((BLOCK_OCTETS)/sizeof(U_LONG))
static MD5_CTX ctx;
/*
* Do first stage of a two stage authenticator generation.
*/
void
MD5auth1crypt(keyno, pkt, length)
u_long keyno;
U_LONG *pkt;
int length; /* length of all encrypted data */
{
authencryptions++;
if (keyno != cache_keyid) {
authkeyuncached++;
if (!authhavekey(keyno)) {
authnokey++;
return;
}
}
MD5Init(&ctx);
MD5Update(&ctx, cache_key, cache_keylen);
MD5Update(&ctx, (char *)pkt, length - 8);
/* just leave the partially computed value in the static MD5_CTX */
}
/*
* Do second state of a two stage authenticator generation.
*/
int
MD5auth2crypt(keyno, pkt, length)
u_long keyno;
U_LONG *pkt;
int length; /* total length of encrypted area */
{
/*
* Don't bother checking the keys. The first stage would have
* handled that. Finish up the generation by also including the
* last 8 bytes of the data area.
*/
MD5Update(&ctx, (char *)(pkt) + length - 8, 8);
MD5Final(&ctx);
memmove((char *) &pkt[NOCRYPT_LONGS + length/sizeof(U_LONG)],
(char *) ctx.digest,
BLOCK_OCTETS);
return (4 + BLOCK_OCTETS);
}
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