2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 #ifndef HEADER_RAND_LCL_H
11 # define HEADER_RAND_LCL_H
13 # include <openssl/aes.h>
14 # include <openssl/evp.h>
15 # include <openssl/sha.h>
16 # include <openssl/hmac.h>
17 # include <openssl/ec.h>
18 # include <openssl/rand_drbg.h>
19 # include "internal/tsan_assist.h"
21 # include "internal/numbers.h"
23 /* How many times to read the TSC as a randomness source. */
24 # define TSC_READ_COUNT 4
26 /* Maximum reseed intervals */
27 # define MAX_RESEED_INTERVAL (1 << 24)
28 # define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
30 /* Default reseed intervals */
31 # define MASTER_RESEED_INTERVAL (1 << 8)
32 # define SLAVE_RESEED_INTERVAL (1 << 16)
33 # define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
34 # define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
39 * Maximum input size for the DRBG (entropy, nonce, personalization string)
41 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
43 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
45 # define DRBG_MAX_LENGTH INT32_MAX
50 * Maximum allocation size for RANDOM_POOL buffers
52 * The max_len value for the buffer provided to the rand_drbg_get_entropy()
53 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
54 * is used. Since this is much too large to be allocated, the rand_pool_new()
55 * function chooses more modest values as default pool length, bounded
56 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
58 * The choice of the RAND_POOL_FACTOR is large enough such that the
59 * RAND_POOL can store a random input which has a lousy entropy rate of
60 * 8/256 (= 0.03125) bits per byte. This input will be sent through the
61 * derivation function which 'compresses' the low quality input into a
62 * high quality output.
64 * The factor 1.5 below is the pessimistic estimate for the extra amount
65 * of entropy required when no get_nonce() callback is defined.
67 # define RAND_POOL_FACTOR 256
68 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
69 3 * (RAND_DRBG_STRENGTH / 16))
71 * = (RAND_POOL_FACTOR * \
72 * 1.5 * (RAND_DRBG_STRENGTH / 8))
76 /* DRBG status values */
77 typedef enum drbg_status_e {
85 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
86 const unsigned char *ent,
88 const unsigned char *nonce,
90 const unsigned char *pers,
93 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
94 const unsigned char *ent,
96 const unsigned char *adin,
99 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
102 const unsigned char *adin,
105 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
112 typedef struct rand_drbg_method_st {
113 RAND_DRBG_instantiate_fn instantiate;
114 RAND_DRBG_reseed_fn reseed;
115 RAND_DRBG_generate_fn generate;
116 RAND_DRBG_uninstantiate_fn uninstantiate;
121 * The state of a DRBG AES-CTR.
123 typedef struct rand_drbg_ctr_st {
125 EVP_CIPHER_CTX *ctx_df;
126 const EVP_CIPHER *cipher;
130 /* Temporary block storage used by ctr_df */
131 unsigned char bltmp[16];
133 unsigned char KX[48];
138 * The 'random pool' acts as a dumb container for collecting random
139 * input from various entropy sources. The pool has no knowledge about
140 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
141 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
142 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
143 * 4) cleanup the random pool again.
145 * The random pool contains no locking mechanism because its scope and
146 * lifetime is intended to be restricted to a single stack frame.
148 struct rand_pool_st {
149 unsigned char *buffer; /* points to the beginning of the random pool */
150 size_t len; /* current number of random bytes contained in the pool */
152 int attached; /* true pool was attached to existing buffer */
154 size_t min_len; /* minimum number of random bytes requested */
155 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
156 size_t entropy; /* current entropy count in bits */
157 size_t entropy_requested; /* requested entropy count in bits */
161 * The state of all types of DRBGs, even though we only have CTR mode
164 struct rand_drbg_st {
167 int secure; /* 1: allocated on the secure heap, 0: otherwise */
168 int type; /* the nid of the underlying algorithm */
170 * Stores the value of the rand_fork_count global as of when we last
171 * reseeded. The DRBG reseeds automatically whenever drbg->fork_count !=
172 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
176 unsigned short flags; /* various external flags */
179 * The random_data is used by RAND_add()/drbg_add() to attach random
180 * data to the global drbg, such that the rand_drbg_get_entropy() callback
181 * can pull it during instantiation and reseeding. This is necessary to
182 * reconcile the different philosophies of the RAND and the RAND_DRBG
183 * with respect to how randomness is added to the RNG during reseeding
186 struct rand_pool_st *seed_pool;
189 * Auxiliary pool for additional data.
191 struct rand_pool_st *adin_pool;
194 * The following parameters are setup by the per-type "init" function.
196 * Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
198 * The parameters are closely related to the ones described in
199 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
200 * crucial difference: In the NIST standard, all counts are given
201 * in bits, whereas in OpenSSL entropy counts are given in bits
202 * and buffer lengths are given in bytes.
204 * Since this difference has lead to some confusion in the past,
205 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
206 * the 'len' suffix has been added to all buffer sizes for
212 size_t min_entropylen, max_entropylen;
213 size_t min_noncelen, max_noncelen;
214 size_t max_perslen, max_adinlen;
216 /* Counts the number of generate requests since the last reseed. */
217 unsigned int reseed_gen_counter;
219 * Maximum number of generate requests until a reseed is required.
220 * This value is ignored if it is zero.
222 unsigned int reseed_interval;
223 /* Stores the time when the last reseeding occurred */
226 * Specifies the maximum time interval (in seconds) between reseeds.
227 * This value is ignored if it is zero.
229 time_t reseed_time_interval;
231 * Counts the number of reseeds since instantiation.
232 * This value is ignored if it is zero.
234 * This counter is used only for seed propagation from the <master> DRBG
235 * to its two children, the <public> and <private> DRBG. This feature is
236 * very special and its sole purpose is to ensure that any randomness which
237 * is added by RAND_add() or RAND_seed() will have an immediate effect on
238 * the output of RAND_bytes() resp. RAND_priv_bytes().
240 TSAN_QUALIFIER unsigned int reseed_prop_counter;
241 unsigned int reseed_next_counter;
246 /* Application data, mainly used in the KATs. */
247 CRYPTO_EX_DATA ex_data;
249 /* Implementation specific data (currently only one implementation) */
254 /* Implementation specific methods */
255 RAND_DRBG_METHOD *meth;
257 /* Callback functions. See comments in rand_lib.c */
258 RAND_DRBG_get_entropy_fn get_entropy;
259 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
260 RAND_DRBG_get_nonce_fn get_nonce;
261 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
264 /* The global RAND method, and the global buffer and DRBG instance. */
265 extern RAND_METHOD rand_meth;
268 * A "generation count" of forks. Incremented in the child process after a
269 * fork. Since rand_fork_count is increment-only, and only ever written to in
270 * the child process of the fork, which is guaranteed to be single-threaded, no
271 * locking is needed for normal (read) accesses; the rest of pthread fork
272 * processing is assumed to introduce the necessary memory barriers. Sibling
273 * children of a given parent will produce duplicate values, but this is not
274 * problematic because the reseeding process pulls input from the system CSPRNG
275 * and/or other global sources, so the siblings will end up generating
276 * different output streams.
278 extern int rand_fork_count;
281 int rand_drbg_restart(RAND_DRBG *drbg,
282 const unsigned char *buffer, size_t len, size_t entropy);
283 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
285 int rand_drbg_lock(RAND_DRBG *drbg);
286 int rand_drbg_unlock(RAND_DRBG *drbg);
287 int rand_drbg_enable_locking(RAND_DRBG *drbg);
290 /* initializes the AES-CTR DRBG implementation */
291 int drbg_ctr_init(RAND_DRBG *drbg);