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 */
35 /* Max size of additional input and personalization string. */
36 # define DRBG_MAX_LENGTH 4096
39 * The quotient between max_{entropy,nonce}len and min_{entropy,nonce}len
41 * The current factor is large enough that the RAND_POOL can store a
42 * random input which has a lousy entropy rate of 0.0625 bits per byte.
43 * This input will be sent through the derivation function which 'compresses'
44 * the low quality input into a high quality output.
46 # define DRBG_MINMAX_FACTOR 128
49 /* DRBG status values */
50 typedef enum drbg_status_e {
58 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
59 const unsigned char *ent,
61 const unsigned char *nonce,
63 const unsigned char *pers,
66 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
67 const unsigned char *ent,
69 const unsigned char *adin,
72 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
75 const unsigned char *adin,
78 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
85 typedef struct rand_drbg_method_st {
86 RAND_DRBG_instantiate_fn instantiate;
87 RAND_DRBG_reseed_fn reseed;
88 RAND_DRBG_generate_fn generate;
89 RAND_DRBG_uninstantiate_fn uninstantiate;
94 * The state of a DRBG AES-CTR.
96 typedef struct rand_drbg_ctr_st {
98 EVP_CIPHER_CTX *ctx_df;
99 const EVP_CIPHER *cipher;
103 /* Temporary block storage used by ctr_df */
104 unsigned char bltmp[16];
106 unsigned char KX[48];
111 * The 'random pool' acts as a dumb container for collecting random
112 * input from various entropy sources. The pool has no knowledge about
113 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
114 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
115 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
116 * 4) cleanup the random pool again.
118 * The random pool contains no locking mechanism because its scope and
119 * lifetime is intended to be restricted to a single stack frame.
121 struct rand_pool_st {
122 unsigned char *buffer; /* points to the beginning of the random pool */
123 size_t len; /* current number of random bytes contained in the pool */
125 size_t min_len; /* minimum number of random bytes requested */
126 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
127 size_t entropy; /* current entropy count in bits */
128 size_t requested_entropy; /* requested entropy count in bits */
132 * The state of all types of DRBGs, even though we only have CTR mode
135 struct rand_drbg_st {
138 int secure; /* 1: allocated on the secure heap, 0: otherwise */
139 int type; /* the nid of the underlying algorithm */
141 * Stores the value of the rand_fork_count global as of when we last
142 * reseeded. The DRG reseeds automatically whenever drbg->fork_count !=
143 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
147 unsigned short flags; /* various external flags */
150 * The random pool is used by RAND_add()/drbg_add() to attach random
151 * data to the global drbg, such that the rand_drbg_get_entropy() callback
152 * can pull it during instantiation and reseeding. This is necessary to
153 * reconcile the different philosophies of the RAND and the RAND_DRBG
154 * with respect to how randomness is added to the RNG during reseeding
157 struct rand_pool_st *pool;
160 * The following parameters are setup by the per-type "init" function.
162 * Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
164 * The parameters are closely related to the ones described in
165 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
166 * crucial difference: In the NIST standard, all counts are given
167 * in bits, whereas in OpenSSL entropy counts are given in bits
168 * and buffer lengths are given in bytes.
170 * Since this difference has lead to some confusion in the past,
171 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
172 * the 'len' suffix has been added to all buffer sizes for
178 size_t min_entropylen, max_entropylen;
179 size_t min_noncelen, max_noncelen;
180 size_t max_perslen, max_adinlen;
182 /* Counts the number of generate requests since the last reseed. */
183 unsigned int generate_counter;
185 * Maximum number of generate requests until a reseed is required.
186 * This value is ignored if it is zero.
188 unsigned int reseed_interval;
189 /* Stores the time when the last reseeding occurred */
192 * Specifies the maximum time interval (in seconds) between reseeds.
193 * This value is ignored if it is zero.
195 time_t reseed_time_interval;
197 * Counts the number of reseeds since instantiation.
198 * This value is ignored if it is zero.
200 * This counter is used only for seed propagation from the <master> DRBG
201 * to its two children, the <public> and <private> DRBG. This feature is
202 * very special and its sole purpose is to ensure that any randomness which
203 * is added by RAND_add() or RAND_seed() will have an immediate effect on
204 * the output of RAND_bytes() resp. RAND_priv_bytes().
206 unsigned int reseed_counter;
211 /* Application data, mainly used in the KATs. */
212 CRYPTO_EX_DATA ex_data;
214 /* Implementation specific data (currently only one implementation) */
219 /* Implementation specific methods */
220 RAND_DRBG_METHOD *meth;
222 /* Callback functions. See comments in rand_lib.c */
223 RAND_DRBG_get_entropy_fn get_entropy;
224 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
225 RAND_DRBG_get_nonce_fn get_nonce;
226 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
229 /* The global RAND method, and the global buffer and DRBG instance. */
230 extern RAND_METHOD rand_meth;
233 * A "generation count" of forks. Incremented in the child process after a
234 * fork. Since rand_fork_count is increment-only, and only ever written to in
235 * the child process of the fork, which is guaranteed to be single-threaded, no
236 * locking is needed for normal (read) accesses; the rest of pthread fork
237 * processing is assumed to introduce the necessary memory barriers. Sibling
238 * children of a given parent will produce duplicate values, but this is not
239 * problematic because the reseeding process pulls input from the system CSPRNG
240 * and/or other global sources, so the siblings will end up generating
241 * different output streams.
243 extern int rand_fork_count;
246 int rand_drbg_restart(RAND_DRBG *drbg,
247 const unsigned char *buffer, size_t len, size_t entropy);
250 int rand_drbg_lock(RAND_DRBG *drbg);
251 int rand_drbg_unlock(RAND_DRBG *drbg);
252 int rand_drbg_enable_locking(RAND_DRBG *drbg);
255 /* initializes the AES-CTR DRBG implementation */
256 int drbg_ctr_init(RAND_DRBG *drbg);