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 # include "internal/numbers.h"
22 /* How many times to read the TSC as a randomness source. */
23 # define TSC_READ_COUNT 4
25 /* Maximum reseed intervals */
26 # define MAX_RESEED_INTERVAL (1 << 24)
27 # define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
29 /* Default reseed intervals */
30 # define MASTER_RESEED_INTERVAL (1 << 8)
31 # define SLAVE_RESEED_INTERVAL (1 << 16)
32 # define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
33 # define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
38 * Maximum input size for the DRBG (entropy, nonce, personalization string)
40 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
42 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
44 # define DRBG_MAX_LENGTH INT32_MAX
49 * Maximum allocation size for RANDOM_POOL buffers
51 * The max_len value for the buffer provided to the rand_drbg_get_entropy()
52 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
53 * is used. Since this is much too large to be allocated, the rand_pool_new()
54 * function chooses more modest values as default pool length, bounded
55 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
57 * The choice of the RAND_POOL_FACTOR is large enough such that the
58 * RAND_POOL can store a random input which has a lousy entropy rate of
59 * 8/256 (= 0.03125) bits per byte. This input will be sent through the
60 * derivation function which 'compresses' the low quality input into a
61 * high quality output.
63 * The factor 1.5 below is the pessimistic estimate for the extra amount
64 * of entropy required when no get_nonce() callback is defined.
66 # define RAND_POOL_FACTOR 256
67 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
68 3 * (RAND_DRBG_STRENGTH / 16))
70 * = (RAND_POOL_FACTOR * \
71 * 1.5 * (RAND_DRBG_STRENGTH / 8))
75 /* DRBG status values */
76 typedef enum drbg_status_e {
84 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
85 const unsigned char *ent,
87 const unsigned char *nonce,
89 const unsigned char *pers,
92 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
93 const unsigned char *ent,
95 const unsigned char *adin,
98 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
101 const unsigned char *adin,
104 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
111 typedef struct rand_drbg_method_st {
112 RAND_DRBG_instantiate_fn instantiate;
113 RAND_DRBG_reseed_fn reseed;
114 RAND_DRBG_generate_fn generate;
115 RAND_DRBG_uninstantiate_fn uninstantiate;
120 * The state of a DRBG AES-CTR.
122 typedef struct rand_drbg_ctr_st {
124 EVP_CIPHER_CTX *ctx_df;
125 const EVP_CIPHER *cipher;
129 /* Temporary block storage used by ctr_df */
130 unsigned char bltmp[16];
132 unsigned char KX[48];
137 * The 'random pool' acts as a dumb container for collecting random
138 * input from various entropy sources. The pool has no knowledge about
139 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
140 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
141 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
142 * 4) cleanup the random pool again.
144 * The random pool contains no locking mechanism because its scope and
145 * lifetime is intended to be restricted to a single stack frame.
147 struct rand_pool_st {
148 unsigned char *buffer; /* points to the beginning of the random pool */
149 size_t len; /* current number of random bytes contained in the pool */
151 int attached; /* true pool was attached to existing buffer */
153 size_t min_len; /* minimum number of random bytes requested */
154 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
155 size_t entropy; /* current entropy count in bits */
156 size_t entropy_requested; /* requested entropy count in bits */
160 * The state of all types of DRBGs, even though we only have CTR mode
163 struct rand_drbg_st {
166 int secure; /* 1: allocated on the secure heap, 0: otherwise */
167 int type; /* the nid of the underlying algorithm */
169 * Stores the value of the rand_fork_count global as of when we last
170 * reseeded. The DRBG reseeds automatically whenever drbg->fork_count !=
171 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
175 unsigned short flags; /* various external flags */
178 * The random_data is used by RAND_add()/drbg_add() to attach random
179 * data to the global drbg, such that the rand_drbg_get_entropy() callback
180 * can pull it during instantiation and reseeding. This is necessary to
181 * reconcile the different philosophies of the RAND and the RAND_DRBG
182 * with respect to how randomness is added to the RNG during reseeding
185 struct rand_pool_st *pool;
188 * The following parameters are setup by the per-type "init" function.
190 * Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
192 * The parameters are closely related to the ones described in
193 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
194 * crucial difference: In the NIST standard, all counts are given
195 * in bits, whereas in OpenSSL entropy counts are given in bits
196 * and buffer lengths are given in bytes.
198 * Since this difference has lead to some confusion in the past,
199 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
200 * the 'len' suffix has been added to all buffer sizes for
206 size_t min_entropylen, max_entropylen;
207 size_t min_noncelen, max_noncelen;
208 size_t max_perslen, max_adinlen;
210 /* Counts the number of generate requests since the last reseed. */
211 unsigned int reseed_gen_counter;
213 * Maximum number of generate requests until a reseed is required.
214 * This value is ignored if it is zero.
216 unsigned int reseed_interval;
217 /* Stores the time when the last reseeding occurred */
220 * Specifies the maximum time interval (in seconds) between reseeds.
221 * This value is ignored if it is zero.
223 time_t reseed_time_interval;
225 * Counts the number of reseeds since instantiation.
226 * This value is ignored if it is zero.
228 * This counter is used only for seed propagation from the <master> DRBG
229 * to its two children, the <public> and <private> DRBG. This feature is
230 * very special and its sole purpose is to ensure that any randomness which
231 * is added by RAND_add() or RAND_seed() will have an immediate effect on
232 * the output of RAND_bytes() resp. RAND_priv_bytes().
234 unsigned int reseed_prop_counter;
239 /* Application data, mainly used in the KATs. */
240 CRYPTO_EX_DATA ex_data;
242 /* Implementation specific data (currently only one implementation) */
247 /* Implementation specific methods */
248 RAND_DRBG_METHOD *meth;
250 /* Callback functions. See comments in rand_lib.c */
251 RAND_DRBG_get_entropy_fn get_entropy;
252 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
253 RAND_DRBG_get_nonce_fn get_nonce;
254 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
257 /* The global RAND method, and the global buffer and DRBG instance. */
258 extern RAND_METHOD rand_meth;
261 * A "generation count" of forks. Incremented in the child process after a
262 * fork. Since rand_fork_count is increment-only, and only ever written to in
263 * the child process of the fork, which is guaranteed to be single-threaded, no
264 * locking is needed for normal (read) accesses; the rest of pthread fork
265 * processing is assumed to introduce the necessary memory barriers. Sibling
266 * children of a given parent will produce duplicate values, but this is not
267 * problematic because the reseeding process pulls input from the system CSPRNG
268 * and/or other global sources, so the siblings will end up generating
269 * different output streams.
271 extern int rand_fork_count;
274 int rand_drbg_restart(RAND_DRBG *drbg,
275 const unsigned char *buffer, size_t len, size_t entropy);
278 int rand_drbg_lock(RAND_DRBG *drbg);
279 int rand_drbg_unlock(RAND_DRBG *drbg);
280 int rand_drbg_enable_locking(RAND_DRBG *drbg);
283 /* initializes the AES-CTR DRBG implementation */
284 int drbg_ctr_init(RAND_DRBG *drbg);