87 lines
1.8 KiB
C
87 lines
1.8 KiB
C
/* $NetBSD: a_md5encrypt.c,v 1.4 1998/03/06 18:17:12 christos Exp $ */
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/*
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* md5crypt - MD5 based authentication routines
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*/
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#include "ntp_types.h"
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#include "ntp_string.h"
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#include "md5.h"
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#include "ntp_stdlib.h"
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extern u_int32 cache_keyid;
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extern char *cache_key;
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extern int cache_keylen;
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#ifndef HAVE_MEMMOVE
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extern void *memmove P((void *, const void *, size_t));
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#endif
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/*
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* Stat counters, imported from data base module
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*/
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extern u_int32 authencryptions;
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extern u_int32 authdecryptions;
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extern u_int32 authkeyuncached;
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extern u_int32 authnokey;
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/*
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* For our purposes an NTP packet looks like:
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*
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* a variable amount of encrypted data, multiple of 8 bytes, followed by:
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* NOCRYPT_OCTETS worth of unencrypted data, followed by:
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* BLOCK_OCTETS worth of ciphered checksum.
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*/
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#define NOCRYPT_OCTETS 4
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#define BLOCK_OCTETS 16
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#define NOCRYPT_int32S ((NOCRYPT_OCTETS)/sizeof(u_int32))
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#define BLOCK_int32S ((BLOCK_OCTETS)/sizeof(u_int32))
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int
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MD5authencrypt(keyno, pkt, length)
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u_int32 keyno;
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u_int32 *pkt;
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int length; /* length of encrypted portion of packet */
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{
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MD5_CTX ctx;
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int len; /* in 4 byte quantities */
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#ifdef __NetBSD__
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unsigned char hash[16];
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#endif
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authencryptions++;
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if (keyno != cache_keyid) {
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authkeyuncached++;
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if (!authhavekey(keyno)) {
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authnokey++;
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return 0;
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}
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}
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len = length / sizeof(u_int32);
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/*
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* Generate the authenticator.
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*/
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MD5Init(&ctx);
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MD5Update(&ctx, (unsigned const char *)cache_key, cache_keylen);
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MD5Update(&ctx, (unsigned const char *)pkt, length);
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#ifdef __NetBSD__
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MD5Final(hash, &ctx);
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#else
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MD5Final(&ctx);
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#endif
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memmove((char *)&pkt[NOCRYPT_int32S + len],
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#ifdef __NetBSD__
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(char *) hash,
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#else
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(char *) ctx.digest,
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#endif
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BLOCK_OCTETS);
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return (4 + BLOCK_OCTETS); /* return size of key and MAC */
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}
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