a_md5encrypt.c revision 82498 
1/*
2 *	MD5 interface for rsaref2.0
3 *
4 * These routines implement an interface for the RSA Laboratories
5 * implementation of the Message Digest 5 (MD5) algorithm. This
6 * algorithm is included in the rsaref2.0 package available from RSA in
7 * the US and foreign countries. Further information is available at
8 * www.rsa.com.
9 */
10
11#include "ntp_machine.h"
12
13#ifdef HAVE_CONFIG_H
14#include <config.h>
15#endif
16
17#include <stdio.h>
18
19#include "ntp_types.h"
20#include "ntp_string.h"
21#include "global.h"
22#include "md5.h"
23#include "ntp_stdlib.h"
24
25#define BLOCK_OCTETS	16	/* message digest size */
26
27
28/*
29 * MD5authencrypt - generate MD5 message authenticator
30 *
31 * Returns length of authenticator field.
32 */
33int
34MD5authencrypt(
35	u_char *key,		/* key pointer */
36	u_int32 *pkt,		/* packet pointer */
37	int length		/* packet length */
38	)
39{
40	MD5_CTX ctx;
41	u_char digest[BLOCK_OCTETS];
42	int i;
43
44	/*
45	 * MD5 with key identifier concatenated with packet.
46	 */
47	MD5Init(&ctx);
48	MD5Update(&ctx, key, (u_int)cache_keylen);
49	MD5Update(&ctx, (u_char *)pkt, (u_int)length);
50	MD5Final(digest, &ctx);
51	i = length / 4;
52	memmove((char *)&pkt[i + 1], (char *)digest, BLOCK_OCTETS);
53	return (BLOCK_OCTETS + 4);
54}
55
56
57/*
58 * MD5authdecrypt - verify MD5 message authenticator
59 *
60 * Returns one if authenticator valid, zero if invalid.
61 */
62int
63MD5authdecrypt(
64	u_char *key,		/* key pointer */
65	u_int32 *pkt,		/* packet pointer */
66	int length, 	/* packet length */
67	int size		/* MAC size */
68	)
69{
70	MD5_CTX ctx;
71	u_char digest[BLOCK_OCTETS];
72
73	/*
74	 * MD5 with key identifier concatenated with packet.
75	 */
76	if (size != BLOCK_OCTETS + 4)
77		return (0);
78	MD5Init(&ctx);
79	MD5Update(&ctx, key, (u_int)cache_keylen);
80	MD5Update(&ctx, (u_char *)pkt, (u_int)length);
81	MD5Final(digest, &ctx);
82	return (!memcmp((char *)digest, (char *)pkt + length + 4,
83		BLOCK_OCTETS));
84}
85