126 lines
2.8 KiB
C
126 lines
2.8 KiB
C
/*
|
|
* auth12crypt.c - routines to support two stage NTP encryption
|
|
*/
|
|
#include "ntp_stdlib.h"
|
|
|
|
/*
|
|
* For our purposes an NTP packet looks like:
|
|
*
|
|
* a variable amount of encrypted data, multiple of 8 bytes, which
|
|
* is encrypted in pass 1, followed by:
|
|
* an 8 byte chunk of data which is encrypted in pass 2
|
|
* NOCRYPT_OCTETS worth of unencrypted data, followed by:
|
|
* BLOCK_OCTETS worth of ciphered checksum.
|
|
*/
|
|
#define NOCRYPT_OCTETS 4
|
|
#define BLOCK_OCTETS 8
|
|
|
|
#define NOCRYPT_LONGS ((NOCRYPT_OCTETS)/sizeof(U_LONG))
|
|
#define BLOCK_LONGS ((BLOCK_OCTETS)/sizeof(U_LONG))
|
|
|
|
/*
|
|
* Imported from the key data base module
|
|
*/
|
|
extern u_long cache_keyid; /* cached key ID */
|
|
extern u_char DEScache_ekeys[]; /* cached decryption keys */
|
|
extern u_char DESzeroekeys[]; /* zero key decryption keys */
|
|
|
|
/*
|
|
* Stat counters, from the database module
|
|
*/
|
|
extern U_LONG authencryptions;
|
|
extern U_LONG authkeyuncached;
|
|
extern U_LONG authnokey;
|
|
|
|
|
|
/*
|
|
* auth1crypt - do the first stage of a two stage encryption
|
|
*/
|
|
void
|
|
DESauth1crypt(keyno, pkt, length)
|
|
u_long keyno;
|
|
U_LONG *pkt;
|
|
int length; /* length of all encrypted data */
|
|
{
|
|
register U_LONG *pd;
|
|
register int i;
|
|
register u_char *keys;
|
|
U_LONG work[2];
|
|
|
|
authencryptions++;
|
|
|
|
if (keyno == 0) {
|
|
keys = DESzeroekeys;
|
|
} else {
|
|
if (keyno != cache_keyid) {
|
|
authkeyuncached++;
|
|
if (!authhavekey(keyno)) {
|
|
authnokey++;
|
|
return;
|
|
}
|
|
}
|
|
keys = DEScache_ekeys;
|
|
}
|
|
|
|
/*
|
|
* Do the first five encryptions. Stick the intermediate result
|
|
* in the mac field. The sixth encryption must wait until the
|
|
* caller freezes a transmit time stamp, and will be done in stage 2.
|
|
*/
|
|
pd = pkt;
|
|
work[0] = work[1] = 0;
|
|
|
|
for (i = (length/BLOCK_OCTETS - 1); i > 0; i--) {
|
|
work[0] ^= *pd++;
|
|
work[1] ^= *pd++;
|
|
DESauth_des(work, keys);
|
|
}
|
|
|
|
/*
|
|
* Space to the end of the packet and stick the intermediate
|
|
* result in the mac field.
|
|
*/
|
|
pd += BLOCK_LONGS + NOCRYPT_LONGS;
|
|
*pd++ = work[0];
|
|
*pd = work[1];
|
|
}
|
|
|
|
|
|
/*
|
|
* auth2crypt - do the second stage of a two stage encryption
|
|
*/
|
|
int
|
|
DESauth2crypt(keyno, pkt, length)
|
|
u_long keyno;
|
|
U_LONG *pkt;
|
|
int length; /* total length of encrypted area */
|
|
{
|
|
register U_LONG *pd;
|
|
register u_char *keys;
|
|
|
|
/*
|
|
* Skip the key check. The call to the first stage should
|
|
* have got it.
|
|
*/
|
|
if (keyno == 0)
|
|
keys = DESzeroekeys;
|
|
else
|
|
keys = DEScache_ekeys;
|
|
|
|
/*
|
|
* The mac currently should hold the results of the first `n'
|
|
* encryptions. We xor in the last block in data section and
|
|
* do the final encryption in place.
|
|
*
|
|
* Get a pointer to the MAC block. XOR in the last two words of
|
|
* the data area. Call the encryption routine.
|
|
*/
|
|
pd = pkt + (length/sizeof(U_LONG)) + NOCRYPT_LONGS;
|
|
|
|
*pd ^= *(pd - NOCRYPT_LONGS - 2);
|
|
*(pd + 1) ^= *(pd - NOCRYPT_LONGS - 1);
|
|
DESauth_des(pd, keys);
|
|
|
|
return 4 + 8; /* return size of key number and MAC */
|
|
}
|