2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (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 */
37 * The number of bytes that constitutes an atomic lump of entropy with respect
38 * to the FIPS 140-2 section 4.9.2 Conditional Tests. The size is somewhat
39 * arbitrary, the smaller the value, the less entropy is consumed on first
40 * read but the higher the probability of the test failing by accident.
42 * The value is in bytes.
44 #define CRNGT_BUFSIZ 16
47 * Maximum input size for the DRBG (entropy, nonce, personalization string)
49 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
51 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
53 # define DRBG_MAX_LENGTH INT32_MAX
55 /* The default nonce */
56 # define DRBG_DEFAULT_PERS_STRING "OpenSSL NIST SP 800-90A DRBG"
59 * Maximum allocation size for RANDOM_POOL buffers
61 * The max_len value for the buffer provided to the rand_drbg_get_entropy()
62 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
63 * is used. Since this is much too large to be allocated, the rand_pool_new()
64 * function chooses more modest values as default pool length, bounded
65 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
67 * The choice of the RAND_POOL_FACTOR is large enough such that the
68 * RAND_POOL can store a random input which has a lousy entropy rate of
69 * 8/256 (= 0.03125) bits per byte. This input will be sent through the
70 * derivation function which 'compresses' the low quality input into a
71 * high quality output.
73 * The factor 1.5 below is the pessimistic estimate for the extra amount
74 * of entropy required when no get_nonce() callback is defined.
76 # define RAND_POOL_FACTOR 256
77 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
78 3 * (RAND_DRBG_STRENGTH / 16))
80 * = (RAND_POOL_FACTOR * \
81 * 1.5 * (RAND_DRBG_STRENGTH / 8))
85 /* DRBG status values */
86 typedef enum drbg_status_e {
94 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
95 const unsigned char *ent,
97 const unsigned char *nonce,
99 const unsigned char *pers,
102 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
103 const unsigned char *ent,
105 const unsigned char *adin,
107 /* generate output */
108 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
111 const unsigned char *adin,
114 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
121 typedef struct rand_drbg_method_st {
122 RAND_DRBG_instantiate_fn instantiate;
123 RAND_DRBG_reseed_fn reseed;
124 RAND_DRBG_generate_fn generate;
125 RAND_DRBG_uninstantiate_fn uninstantiate;
128 /* 888 bits from SP800-90Ar1 10.1 table 2 */
129 #define HASH_PRNG_MAX_SEEDLEN (888/8)
131 typedef struct rand_drbg_hash_st {
135 unsigned char V[HASH_PRNG_MAX_SEEDLEN];
136 unsigned char C[HASH_PRNG_MAX_SEEDLEN];
137 /* Temporary value storage: should always exceed max digest length */
138 unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
141 typedef struct rand_drbg_hmac_st {
145 unsigned char K[EVP_MAX_MD_SIZE];
146 unsigned char V[EVP_MAX_MD_SIZE];
150 * The state of a DRBG AES-CTR.
152 typedef struct rand_drbg_ctr_st {
154 EVP_CIPHER_CTX *ctx_df;
155 const EVP_CIPHER *cipher;
159 /* Temporary block storage used by ctr_df */
160 unsigned char bltmp[16];
162 unsigned char KX[48];
167 * The 'random pool' acts as a dumb container for collecting random
168 * input from various entropy sources. The pool has no knowledge about
169 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
170 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
171 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
172 * 4) cleanup the random pool again.
174 * The random pool contains no locking mechanism because its scope and
175 * lifetime is intended to be restricted to a single stack frame.
177 struct rand_pool_st {
178 unsigned char *buffer; /* points to the beginning of the random pool */
179 size_t len; /* current number of random bytes contained in the pool */
181 int attached; /* true pool was attached to existing buffer */
183 size_t min_len; /* minimum number of random bytes requested */
184 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
185 size_t entropy; /* current entropy count in bits */
186 size_t entropy_requested; /* requested entropy count in bits */
190 * The state of all types of DRBGs, even though we only have CTR mode
193 struct rand_drbg_st {
195 /* The library context this DRBG is associated with, if any */
198 int secure; /* 1: allocated on the secure heap, 0: otherwise */
199 int type; /* the nid of the underlying algorithm */
201 * Stores the value of the rand_fork_count global as of when we last
202 * reseeded. The DRBG reseeds automatically whenever drbg->fork_count !=
203 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
207 unsigned short flags; /* various external flags */
210 * The random_data is used by RAND_add()/drbg_add() to attach random
211 * data to the global drbg, such that the rand_drbg_get_entropy() callback
212 * can pull it during instantiation and reseeding. This is necessary to
213 * reconcile the different philosophies of the RAND and the RAND_DRBG
214 * with respect to how randomness is added to the RNG during reseeding
217 struct rand_pool_st *seed_pool;
220 * Auxiliary pool for additional data.
222 struct rand_pool_st *adin_pool;
225 * The following parameters are setup by the per-type "init" function.
227 * The supported types and their init functions are:
228 * (1) CTR_DRBG: drbg_ctr_init().
229 * (2) HMAC_DRBG: drbg_hmac_init().
230 * (3) HASH_DRBG: drbg_hash_init().
232 * The parameters are closely related to the ones described in
233 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
234 * crucial difference: In the NIST standard, all counts are given
235 * in bits, whereas in OpenSSL entropy counts are given in bits
236 * and buffer lengths are given in bytes.
238 * Since this difference has lead to some confusion in the past,
239 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
240 * the 'len' suffix has been added to all buffer sizes for
246 size_t min_entropylen, max_entropylen;
247 size_t min_noncelen, max_noncelen;
248 size_t max_perslen, max_adinlen;
251 * Counts the number of generate requests since the last reseed
252 * (Starts at 1). This value is the reseed_counter as defined in
255 unsigned int reseed_gen_counter;
257 * Maximum number of generate requests until a reseed is required.
258 * This value is ignored if it is zero.
260 unsigned int reseed_interval;
261 /* Stores the time when the last reseeding occurred */
264 * Specifies the maximum time interval (in seconds) between reseeds.
265 * This value is ignored if it is zero.
267 time_t reseed_time_interval;
269 * Counts the number of reseeds since instantiation.
270 * This value is ignored if it is zero.
272 * This counter is used only for seed propagation from the <master> DRBG
273 * to its two children, the <public> and <private> DRBG. This feature is
274 * very special and its sole purpose is to ensure that any randomness which
275 * is added by RAND_add() or RAND_seed() will have an immediate effect on
276 * the output of RAND_bytes() resp. RAND_priv_bytes().
278 TSAN_QUALIFIER unsigned int reseed_prop_counter;
279 unsigned int reseed_next_counter;
284 /* Application data, mainly used in the KATs. */
285 CRYPTO_EX_DATA ex_data;
287 /* Implementation specific data */
294 /* Implementation specific methods */
295 RAND_DRBG_METHOD *meth;
297 /* Callback functions. See comments in rand_lib.c */
298 RAND_DRBG_get_entropy_fn get_entropy;
299 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
300 RAND_DRBG_get_nonce_fn get_nonce;
301 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
304 /* The global RAND method, and the global buffer and DRBG instance. */
305 extern RAND_METHOD rand_meth;
308 * A "generation count" of forks. Incremented in the child process after a
309 * fork. Since rand_fork_count is increment-only, and only ever written to in
310 * the child process of the fork, which is guaranteed to be single-threaded, no
311 * locking is needed for normal (read) accesses; the rest of pthread fork
312 * processing is assumed to introduce the necessary memory barriers. Sibling
313 * children of a given parent will produce duplicate values, but this is not
314 * problematic because the reseeding process pulls input from the system CSPRNG
315 * and/or other global sources, so the siblings will end up generating
316 * different output streams.
318 extern int rand_fork_count;
321 int rand_drbg_restart(RAND_DRBG *drbg,
322 const unsigned char *buffer, size_t len, size_t entropy);
323 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
325 int rand_drbg_lock(RAND_DRBG *drbg);
326 int rand_drbg_unlock(RAND_DRBG *drbg);
327 int rand_drbg_enable_locking(RAND_DRBG *drbg);
330 /* initializes the DRBG implementation */
331 int drbg_ctr_init(RAND_DRBG *drbg);
332 int drbg_hash_init(RAND_DRBG *drbg);
333 int drbg_hmac_init(RAND_DRBG *drbg);
336 * Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
337 * These need to be exposed for the unit tests.
339 int rand_crngt_get_entropy_cb(unsigned char *buf, unsigned char *md,
340 unsigned int *md_size);
341 extern int (*crngt_get_entropy)(unsigned char *buf, unsigned char *md,
342 unsigned int *md_size);
343 int rand_crngt_init(void);
344 void rand_crngt_cleanup(void);
347 * Expose the run once initialisation function for the unit tests because.
348 * they need to restart from scratch to validate the first block is skipped
351 int rand_crngt_single_init(void);