2 * Copyright 1988 by the Massachusetts Institute of Technology.
4 * For copying and distribution information, please see the file
7 * New pseudo-random key generator, using DES encryption to make the
8 * pseudo-random cycle as hard to break as DES.
10 * Written by Mark Lillibridge, MIT Project Athena
12 * Under U.S. law, this software may not be exported outside the US
13 * without license from the U.S. Commerce department.
16 #include <mit-cpyright.h>
18 #include <afsconfig.h>
19 #include <afs/param.h>
28 #include "des_internal.h"
29 #include "des_prototypes.h"
31 #ifdef AFS_PTHREAD_ENV
42 static afs_int32 des_set_sequence_number(des_cblock new_sequence_number);
43 static afs_int32 des_generate_random_block(des_cblock block);
45 #define XPRT_NEW_RND_KEY
47 static int is_inited = 0;
48 #ifdef AFS_PTHREAD_ENV
50 * This mutex protects the following global variables:
55 pthread_mutex_t des_init_mutex;
56 #define LOCK_INIT assert(pthread_mutex_lock(&des_init_mutex)==0)
57 #define UNLOCK_INIT assert(pthread_mutex_unlock(&des_init_mutex)==0)
63 * des_random_key: create a random des key
65 * You should call des_set_random_number_generater_seed at least
66 * once before this routine is called. If you haven't, I'll try
67 * to add a little randomness to the start point anyway. Yes,
68 * it recurses. Deal with it.
70 * Notes: the returned key has correct parity and is guarenteed not
71 * to be a weak des key. Des_generate_random_block is used to
72 * provide the random bits.
75 des_random_key(des_cblock key)
79 des_init_random_number_generator(key);
83 des_generate_random_block(key);
84 des_fixup_key_parity(key);
85 } while (des_is_weak_key(key));
91 * des_init_random_number_generator:
93 * This routine takes a secret key possibly shared by a number
94 * of servers and uses it to generate a random number stream that is
95 * not shared by any of the other servers. It does this by using the current
96 * process id, host id, and the current time to the nearest second. The
97 * resulting stream seed is not useful information for cracking the secret
98 * key. Moreover, this routine keeps no copy of the secret key.
99 * This routine is used for example, by the kerberos server(s) with the
100 * key in question being the kerberos master key.
102 * Note: this routine calls des_set_random_generator_seed.
104 #if !defined(BSDUNIX) && !defined(AFS_SGI_ENV) && !defined(AFS_NT40_ENV) && !defined(AFS_LINUX20_ENV) && !defined(AFS_DARWIN_ENV)
105 you lose ... (aka, you get to implement an analog of this for your system ...)
109 #include <winsock2.h>
111 #include <afs/afsutil.h>
113 #include <sys/time.h>
118 des_init_random_number_generator(des_cblock key)
120 struct { /* This must be 64 bits exactly */
121 afs_int32 process_id;
124 struct timeval time; /* this must also be 64 bits exactly */
129 * use a host id and process id in generating the seed to ensure
130 * that different servers have different streams:
132 #if !defined(AFS_HPUX_ENV) && !defined(AFS_NT40_ENV)
133 seed.host_id = gethostid();
135 seed.process_id = getpid();
138 * Generate a tempory value that depends on the key, host_id, and
139 * process_id such that it gives no useful information about the key:
141 des_set_random_generator_seed(key);
142 des_set_sequence_number((unsigned char *)&seed);
143 des_random_key(new_key);
146 * use it to select a random stream:
148 des_set_random_generator_seed(new_key);
151 * use a time stamp to ensure that a server started later does not reuse
154 gettimeofday(&time, NULL);
155 des_set_sequence_number((unsigned char *)&time);
158 * use the time stamp finally to select the final seed using the
159 * current random number stream:
161 des_random_key(new_key);
162 des_set_random_generator_seed(new_key);
165 #endif /* ifdef BSDUNIX */
168 * This module implements a random number generator faculty such that the next
169 * number in any random number stream is very hard to predict without knowing
170 * the seed for that stream even given the preceeding random numbers.
174 * The secret des key schedule for the current stream of random numbers:
179 } random_sequence_key;
182 * The sequence # in the current stream of random numbers:
184 static unsigned char sequence_number[8];
186 #ifdef AFS_PTHREAD_ENV
188 * This mutex protects the following global variables:
189 * random_sequence_key
194 pthread_mutex_t des_random_mutex;
195 #define LOCK_RANDOM assert(pthread_mutex_lock(&des_random_mutex)==0)
196 #define UNLOCK_RANDOM assert(pthread_mutex_unlock(&des_random_mutex)==0)
199 #define UNLOCK_RANDOM
203 * des_set_random_generator_seed: this routine is used to select a random
204 * number stream. The stream that results is
205 * totally determined by the passed in key.
206 * (I.e., calling this routine again with the
207 * same key allows repeating a sequence of
210 * Requires: key is a valid des key. I.e., has correct parity and is not a
214 des_set_random_generator_seed(des_cblock key)
218 /* select the new stream: (note errors are not possible here...) */
220 des_key_sched(key, random_sequence_key.d);
222 /* "seek" to the start of the stream: */
223 for (i = 0; i < 8; i++)
224 sequence_number[i] = 0;
229 * des_set_sequence_number: this routine is used to set the sequence number
230 * of the current random number stream. This routine
231 * may be used to "seek" within the current random
234 * Note that des_set_random_generator_seed resets the sequence number to 0.
237 des_set_sequence_number(des_cblock new_sequence_number)
240 memcpy((char *)sequence_number, (char *)new_sequence_number,
241 sizeof(sequence_number));
247 * des_generate_random_block: routine to return the next random number
248 * from the current random number stream.
249 * The returned number is 64 bits long.
251 * Requires: des_set_random_generator_seed must have been called at least once
252 * before this routine is called.
255 des_generate_random_block(des_cblock block)
260 * Encrypt the sequence number to get the new random block:
263 des_ecb_encrypt(sequence_number, block, random_sequence_key.d, 1);
266 * Increment the sequence number as an 8 byte unsigned number with wrap:
269 for (i = 0; i < 8; i++) {
270 sequence_number[i] = (sequence_number[i] + 1) & 0xff;
271 if (sequence_number[i])