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"
20 # include "internal/rand_int.h"
22 # include "internal/numbers.h"
24 /* How many times to read the TSC as a randomness source. */
25 # define TSC_READ_COUNT 4
27 /* Maximum reseed intervals */
28 # define MAX_RESEED_INTERVAL (1 << 24)
29 # define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
31 /* Default reseed intervals */
32 # define MASTER_RESEED_INTERVAL (1 << 8)
33 # define SLAVE_RESEED_INTERVAL (1 << 16)
34 # define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
35 # define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
38 * The number of bytes that constitutes an atomic lump of entropy with respect
39 * to the FIPS 140-2 section 4.9.2 Conditional Tests. The size is somewhat
40 * arbitrary, the smaller the value, the less entropy is consumed on first
41 * read but the higher the probability of the test failing by accident.
43 * The value is in bytes.
45 #define CRNGT_BUFSIZ 16
48 * Maximum input size for the DRBG (entropy, nonce, personalization string)
50 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
52 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
54 # define DRBG_MAX_LENGTH INT32_MAX
56 /* The default nonce */
57 # define DRBG_DEFAULT_PERS_STRING "OpenSSL NIST SP 800-90A DRBG"
60 * Maximum allocation size for RANDOM_POOL buffers
62 * The max_len value for the buffer provided to the rand_drbg_get_entropy()
63 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
64 * is used. Since this is much too large to be allocated, the rand_pool_new()
65 * function chooses more modest values as default pool length, bounded
66 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
68 * The choice of the RAND_POOL_FACTOR is large enough such that the
69 * RAND_POOL can store a random input which has a lousy entropy rate of
70 * 8/256 (= 0.03125) bits per byte. This input will be sent through the
71 * derivation function which 'compresses' the low quality input into a
72 * high quality output.
74 * The factor 1.5 below is the pessimistic estimate for the extra amount
75 * of entropy required when no get_nonce() callback is defined.
77 # define RAND_POOL_FACTOR 256
78 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
79 3 * (RAND_DRBG_STRENGTH / 16))
81 * = (RAND_POOL_FACTOR * \
82 * 1.5 * (RAND_DRBG_STRENGTH / 8))
86 /* DRBG status values */
87 typedef enum drbg_status_e {
95 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
96 const unsigned char *ent,
98 const unsigned char *nonce,
100 const unsigned char *pers,
103 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
104 const unsigned char *ent,
106 const unsigned char *adin,
108 /* generate output */
109 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
112 const unsigned char *adin,
115 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
122 typedef struct rand_drbg_method_st {
123 RAND_DRBG_instantiate_fn instantiate;
124 RAND_DRBG_reseed_fn reseed;
125 RAND_DRBG_generate_fn generate;
126 RAND_DRBG_uninstantiate_fn uninstantiate;
129 /* 888 bits from SP800-90Ar1 10.1 table 2 */
130 #define HASH_PRNG_MAX_SEEDLEN (888/8)
132 typedef struct rand_drbg_hash_st {
136 unsigned char V[HASH_PRNG_MAX_SEEDLEN];
137 unsigned char C[HASH_PRNG_MAX_SEEDLEN];
138 /* Temporary value storage: should always exceed max digest length */
139 unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
142 typedef struct rand_drbg_hmac_st {
146 unsigned char K[EVP_MAX_MD_SIZE];
147 unsigned char V[EVP_MAX_MD_SIZE];
151 * The state of a DRBG AES-CTR.
153 typedef struct rand_drbg_ctr_st {
155 EVP_CIPHER_CTX *ctx_df;
160 /* Temporary block storage used by ctr_df */
161 unsigned char bltmp[16];
163 unsigned char KX[48];
168 * The 'random pool' acts as a dumb container for collecting random
169 * input from various entropy sources. The pool has no knowledge about
170 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
171 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
172 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
173 * 4) cleanup the random pool again.
175 * The random pool contains no locking mechanism because its scope and
176 * lifetime is intended to be restricted to a single stack frame.
178 struct rand_pool_st {
179 unsigned char *buffer; /* points to the beginning of the random pool */
180 size_t len; /* current number of random bytes contained in the pool */
182 int attached; /* true pool was attached to existing buffer */
184 size_t min_len; /* minimum number of random bytes requested */
185 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
186 size_t entropy; /* current entropy count in bits */
187 size_t entropy_requested; /* requested entropy count in bits */
191 * The state of all types of DRBGs, even though we only have CTR mode
194 struct rand_drbg_st {
196 /* The library context this DRBG is associated with, if any */
199 int secure; /* 1: allocated on the secure heap, 0: otherwise */
200 int type; /* the nid of the underlying algorithm */
202 * Stores the value of the rand_fork_count global as of when we last
203 * reseeded. The DRBG reseeds automatically whenever drbg->fork_count !=
204 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
208 unsigned short flags; /* various external flags */
211 * The random_data is used by RAND_add()/drbg_add() to attach random
212 * data to the global drbg, such that the rand_drbg_get_entropy() callback
213 * can pull it during instantiation and reseeding. This is necessary to
214 * reconcile the different philosophies of the RAND and the RAND_DRBG
215 * with respect to how randomness is added to the RNG during reseeding
218 struct rand_pool_st *seed_pool;
221 * Auxiliary pool for additional data.
223 struct rand_pool_st *adin_pool;
226 * The following parameters are setup by the per-type "init" function.
228 * The supported types and their init functions are:
229 * (1) CTR_DRBG: drbg_ctr_init().
230 * (2) HMAC_DRBG: drbg_hmac_init().
231 * (3) HASH_DRBG: drbg_hash_init().
233 * The parameters are closely related to the ones described in
234 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
235 * crucial difference: In the NIST standard, all counts are given
236 * in bits, whereas in OpenSSL entropy counts are given in bits
237 * and buffer lengths are given in bytes.
239 * Since this difference has lead to some confusion in the past,
240 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
241 * the 'len' suffix has been added to all buffer sizes for
247 size_t min_entropylen, max_entropylen;
248 size_t min_noncelen, max_noncelen;
249 size_t max_perslen, max_adinlen;
252 * Counts the number of generate requests since the last reseed
253 * (Starts at 1). This value is the reseed_counter as defined in
256 unsigned int reseed_gen_counter;
258 * Maximum number of generate requests until a reseed is required.
259 * This value is ignored if it is zero.
261 unsigned int reseed_interval;
262 /* Stores the time when the last reseeding occurred */
265 * Specifies the maximum time interval (in seconds) between reseeds.
266 * This value is ignored if it is zero.
268 time_t reseed_time_interval;
270 * Counts the number of reseeds since instantiation.
271 * This value is ignored if it is zero.
273 * This counter is used only for seed propagation from the <master> DRBG
274 * to its two children, the <public> and <private> DRBG. This feature is
275 * very special and its sole purpose is to ensure that any randomness which
276 * is added by RAND_add() or RAND_seed() will have an immediate effect on
277 * the output of RAND_bytes() resp. RAND_priv_bytes().
279 TSAN_QUALIFIER unsigned int reseed_prop_counter;
280 unsigned int reseed_next_counter;
285 /* Application data, mainly used in the KATs. */
286 CRYPTO_EX_DATA ex_data;
288 /* Implementation specific data */
295 /* Implementation specific methods */
296 RAND_DRBG_METHOD *meth;
298 /* Callback functions. See comments in rand_lib.c */
299 RAND_DRBG_get_entropy_fn get_entropy;
300 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
301 RAND_DRBG_get_nonce_fn get_nonce;
302 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
305 /* The global RAND method, and the global buffer and DRBG instance. */
306 extern RAND_METHOD rand_meth;
309 * A "generation count" of forks. Incremented in the child process after a
310 * fork. Since rand_fork_count is increment-only, and only ever written to in
311 * the child process of the fork, which is guaranteed to be single-threaded, no
312 * locking is needed for normal (read) accesses; the rest of pthread fork
313 * processing is assumed to introduce the necessary memory barriers. Sibling
314 * children of a given parent will produce duplicate values, but this is not
315 * problematic because the reseeding process pulls input from the system CSPRNG
316 * and/or other global sources, so the siblings will end up generating
317 * different output streams.
319 extern int rand_fork_count;
322 int rand_drbg_restart(RAND_DRBG *drbg,
323 const unsigned char *buffer, size_t len, size_t entropy);
324 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
326 int rand_drbg_lock(RAND_DRBG *drbg);
327 int rand_drbg_unlock(RAND_DRBG *drbg);
328 int rand_drbg_enable_locking(RAND_DRBG *drbg);
331 /* initializes the DRBG implementation */
332 int drbg_ctr_init(RAND_DRBG *drbg);
333 int drbg_hash_init(RAND_DRBG *drbg);
334 int drbg_hmac_init(RAND_DRBG *drbg);
337 * Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
338 * These need to be exposed for the unit tests.
340 int rand_crngt_get_entropy_cb(OPENSSL_CTX *ctx, RAND_POOL *pool,
341 unsigned char *buf, unsigned char *md,
342 unsigned int *md_size);
343 extern int (*crngt_get_entropy)(OPENSSL_CTX *ctx, RAND_POOL *pool,
344 unsigned char *buf, unsigned char *md,
345 unsigned int *md_size);