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>
20 /* How many times to read the TSC as a randomness source. */
21 # define TSC_READ_COUNT 4
23 /* Maximum reseed intervals */
24 # define MAX_RESEED_INTERVAL (1 << 24)
25 # define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
27 /* Default reseed intervals */
28 # define MASTER_RESEED_INTERVAL (1 << 8)
29 # define SLAVE_RESEED_INTERVAL (1 << 16)
30 # define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
31 # define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
36 * Maximum input size for the DRBG (entropy, nonce, personalization string)
38 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
40 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
42 # define DRBG_MAX_LENGTH INT32_MAX
47 * Maximum allocation size for RANDOM_POOL buffers
49 * The max_len value for the buffer provided to the rand_drbg_get_entropy()
50 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
51 * is used. Since this is much too large to be allocated, the rand_pool_new()
52 * function chooses more modest values as default pool length, bounded
53 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
55 * The choice of the RAND_POOL_FACTOR is large enough such that the
56 * RAND_POOL can store a random input which has a lousy entropy rate of
57 * 8/256 (= 0.03125) bits per byte. This input will be sent through the
58 * derivation function which 'compresses' the low quality input into a
59 * high quality output.
61 * The factor 1.5 below is the pessimistic estimate for the extra amount
62 * of entropy required when no get_nonce() callback is defined.
64 # define RAND_POOL_FACTOR 256
65 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
66 3 * (RAND_DRBG_STRENGTH / 16))
68 * = (RAND_POOL_FACTOR * \
69 * 1.5 * (RAND_DRBG_STRENGTH / 8))
73 /* DRBG status values */
74 typedef enum drbg_status_e {
82 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
83 const unsigned char *ent,
85 const unsigned char *nonce,
87 const unsigned char *pers,
90 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
91 const unsigned char *ent,
93 const unsigned char *adin,
96 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
99 const unsigned char *adin,
102 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
109 typedef struct rand_drbg_method_st {
110 RAND_DRBG_instantiate_fn instantiate;
111 RAND_DRBG_reseed_fn reseed;
112 RAND_DRBG_generate_fn generate;
113 RAND_DRBG_uninstantiate_fn uninstantiate;
118 * The state of a DRBG AES-CTR.
120 typedef struct rand_drbg_ctr_st {
122 EVP_CIPHER_CTX *ctx_df;
123 const EVP_CIPHER *cipher;
127 /* Temporary block storage used by ctr_df */
128 unsigned char bltmp[16];
130 unsigned char KX[48];
135 * The 'random pool' acts as a dumb container for collecting random
136 * input from various entropy sources. The pool has no knowledge about
137 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
138 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
139 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
140 * 4) cleanup the random pool again.
142 * The random pool contains no locking mechanism because its scope and
143 * lifetime is intended to be restricted to a single stack frame.
145 struct rand_pool_st {
146 unsigned char *buffer; /* points to the beginning of the random pool */
147 size_t len; /* current number of random bytes contained in the pool */
149 int attached; /* true pool was attached to existing buffer */
151 size_t min_len; /* minimum number of random bytes requested */
152 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
153 size_t entropy; /* current entropy count in bits */
154 size_t entropy_requested; /* requested entropy count in bits */
158 * The state of all types of DRBGs, even though we only have CTR mode
161 struct rand_drbg_st {
164 int secure; /* 1: allocated on the secure heap, 0: otherwise */
165 int type; /* the nid of the underlying algorithm */
167 * Stores the value of the rand_fork_count global as of when we last
168 * reseeded. The DRG reseeds automatically whenever drbg->fork_count !=
169 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
173 unsigned short flags; /* various external flags */
176 * The random_data is used by RAND_add()/drbg_add() to attach random
177 * data to the global drbg, such that the rand_drbg_get_entropy() callback
178 * can pull it during instantiation and reseeding. This is necessary to
179 * reconcile the different philosophies of the RAND and the RAND_DRBG
180 * with respect to how randomness is added to the RNG during reseeding
183 struct rand_pool_st *pool;
186 * The following parameters are setup by the per-type "init" function.
188 * Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
190 * The parameters are closely related to the ones described in
191 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
192 * crucial difference: In the NIST standard, all counts are given
193 * in bits, whereas in OpenSSL entropy counts are given in bits
194 * and buffer lengths are given in bytes.
196 * Since this difference has lead to some confusion in the past,
197 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
198 * the 'len' suffix has been added to all buffer sizes for
204 size_t min_entropylen, max_entropylen;
205 size_t min_noncelen, max_noncelen;
206 size_t max_perslen, max_adinlen;
208 /* Counts the number of generate requests since the last reseed. */
209 unsigned int generate_counter;
211 * Maximum number of generate requests until a reseed is required.
212 * This value is ignored if it is zero.
214 unsigned int reseed_interval;
215 /* Stores the time when the last reseeding occurred */
218 * Specifies the maximum time interval (in seconds) between reseeds.
219 * This value is ignored if it is zero.
221 time_t reseed_time_interval;
223 * Counts the number of reseeds since instantiation.
224 * This value is ignored if it is zero.
226 * This counter is used only for seed propagation from the <master> DRBG
227 * to its two children, the <public> and <private> DRBG. This feature is
228 * very special and its sole purpose is to ensure that any randomness which
229 * is added by RAND_add() or RAND_seed() will have an immediate effect on
230 * the output of RAND_bytes() resp. RAND_priv_bytes().
232 unsigned int reseed_counter;
237 /* Application data, mainly used in the KATs. */
238 CRYPTO_EX_DATA ex_data;
240 /* Implementation specific data (currently only one implementation) */
245 /* Implementation specific methods */
246 RAND_DRBG_METHOD *meth;
248 /* Callback functions. See comments in rand_lib.c */
249 RAND_DRBG_get_entropy_fn get_entropy;
250 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
251 RAND_DRBG_get_nonce_fn get_nonce;
252 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
255 /* The global RAND method, and the global buffer and DRBG instance. */
256 extern RAND_METHOD rand_meth;
259 * A "generation count" of forks. Incremented in the child process after a
260 * fork. Since rand_fork_count is increment-only, and only ever written to in
261 * the child process of the fork, which is guaranteed to be single-threaded, no
262 * locking is needed for normal (read) accesses; the rest of pthread fork
263 * processing is assumed to introduce the necessary memory barriers. Sibling
264 * children of a given parent will produce duplicate values, but this is not
265 * problematic because the reseeding process pulls input from the system CSPRNG
266 * and/or other global sources, so the siblings will end up generating
267 * different output streams.
269 extern int rand_fork_count;
272 int rand_drbg_restart(RAND_DRBG *drbg,
273 const unsigned char *buffer, size_t len, size_t entropy);
276 int rand_drbg_lock(RAND_DRBG *drbg);
277 int rand_drbg_unlock(RAND_DRBG *drbg);
278 int rand_drbg_enable_locking(RAND_DRBG *drbg);
281 /* initializes the AES-CTR DRBG implementation */
282 int drbg_ctr_init(RAND_DRBG *drbg);