87 lines
1.9 KiB
C
87 lines
1.9 KiB
C
/*
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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_long cache_keyid;
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extern char *cache_key;
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extern int cache_keylen;
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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_LONG authencryptions;
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extern U_LONG authdecryptions;
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extern U_LONG authkeyuncached;
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extern U_LONG 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_LONGS ((NOCRYPT_OCTETS)/sizeof(U_LONG))
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#define BLOCK_LONGS ((BLOCK_OCTETS)/sizeof(U_LONG))
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static MD5_CTX ctx;
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/*
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* Do first stage of a two stage authenticator generation.
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*/
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void
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MD5auth1crypt(keyno, pkt, length)
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u_long keyno;
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U_LONG *pkt;
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int length; /* length of all encrypted data */
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{
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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;
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}
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}
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MD5Init(&ctx);
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MD5Update(&ctx, cache_key, cache_keylen);
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MD5Update(&ctx, (char *)pkt, length - 8);
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/* just leave the partially computed value in the static MD5_CTX */
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}
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/*
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* Do second state of a two stage authenticator generation.
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*/
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int
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MD5auth2crypt(keyno, pkt, length)
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u_long keyno;
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U_LONG *pkt;
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int length; /* total length of encrypted area */
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{
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/*
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* Don't bother checking the keys. The first stage would have
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* handled that. Finish up the generation by also including the
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* last 8 bytes of the data area.
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*/
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MD5Update(&ctx, (char *)(pkt) + length - 8, 8);
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MD5Final(&ctx);
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memmove((char *) &pkt[NOCRYPT_LONGS + length/sizeof(U_LONG)],
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(char *) ctx.digest,
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BLOCK_OCTETS);
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return (4 + BLOCK_OCTETS);
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}
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