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 * Initial allocation minimum.
88 * There is a distinction between the secure and normal allocation minimums.
89 * Ideally, the secure allocation size should be a power of two. The normal
90 * allocation size doesn't have any such restriction.
92 * The secure value is based on 128 bits of secure material, which is 16 bytes.
93 * Typically, the DRBGs will set a minimum larger than this so optimal
94 * allocation ought to take place (for full quality seed material).
96 * The normal value has been chosed by noticing that the rand_drbg_get_nonce
97 * function is usually the largest of the built in allocation (twenty four
98 * bytes and then appending another sixteen bytes). This means the buffer ends
99 * with 40 bytes. The value of forty eight is comfortably above this which
100 * allows some slack in the platform specific values used.
102 # define RAND_POOL_MIN_ALLOCATION(secure) ((secure) ? 16 : 48)
104 /* DRBG status values */
105 typedef enum drbg_status_e {
113 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
114 const unsigned char *ent,
116 const unsigned char *nonce,
118 const unsigned char *pers,
121 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
122 const unsigned char *ent,
124 const unsigned char *adin,
126 /* generate output */
127 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
130 const unsigned char *adin,
133 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
140 typedef struct rand_drbg_method_st {
141 RAND_DRBG_instantiate_fn instantiate;
142 RAND_DRBG_reseed_fn reseed;
143 RAND_DRBG_generate_fn generate;
144 RAND_DRBG_uninstantiate_fn uninstantiate;
147 /* 888 bits from SP800-90Ar1 10.1 table 2 */
148 #define HASH_PRNG_MAX_SEEDLEN (888/8)
150 typedef struct rand_drbg_hash_st {
154 unsigned char V[HASH_PRNG_MAX_SEEDLEN];
155 unsigned char C[HASH_PRNG_MAX_SEEDLEN];
156 /* Temporary value storage: should always exceed max digest length */
157 unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
160 typedef struct rand_drbg_hmac_st {
164 unsigned char K[EVP_MAX_MD_SIZE];
165 unsigned char V[EVP_MAX_MD_SIZE];
169 * The state of a DRBG AES-CTR.
171 typedef struct rand_drbg_ctr_st {
173 EVP_CIPHER_CTX *ctx_df;
178 /* Temporary block storage used by ctr_df */
179 unsigned char bltmp[16];
181 unsigned char KX[48];
186 * The 'random pool' acts as a dumb container for collecting random
187 * input from various entropy sources. The pool has no knowledge about
188 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
189 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
190 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
191 * 4) cleanup the random pool again.
193 * The random pool contains no locking mechanism because its scope and
194 * lifetime is intended to be restricted to a single stack frame.
196 struct rand_pool_st {
197 unsigned char *buffer; /* points to the beginning of the random pool */
198 size_t len; /* current number of random bytes contained in the pool */
200 int attached; /* true pool was attached to existing buffer */
201 int secure; /* 1: allocated on the secure heap, 0: otherwise */
203 size_t min_len; /* minimum number of random bytes requested */
204 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
205 size_t alloc_len; /* current number of bytes allocated */
206 size_t entropy; /* current entropy count in bits */
207 size_t entropy_requested; /* requested entropy count in bits */
211 * The state of all types of DRBGs, even though we only have CTR mode
214 struct rand_drbg_st {
216 /* The library context this DRBG is associated with, if any */
219 int secure; /* 1: allocated on the secure heap, 0: otherwise */
220 int type; /* the nid of the underlying algorithm */
222 * Stores the value of the rand_fork_count global as of when we last
223 * reseeded. The DRBG reseeds automatically whenever drbg->fork_count !=
224 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
228 unsigned short flags; /* various external flags */
231 * The random_data is used by RAND_add()/drbg_add() to attach random
232 * data to the global drbg, such that the rand_drbg_get_entropy() callback
233 * can pull it during instantiation and reseeding. This is necessary to
234 * reconcile the different philosophies of the RAND and the RAND_DRBG
235 * with respect to how randomness is added to the RNG during reseeding
238 struct rand_pool_st *seed_pool;
241 * Auxiliary pool for additional data.
243 struct rand_pool_st *adin_pool;
246 * The following parameters are setup by the per-type "init" function.
248 * The supported types and their init functions are:
249 * (1) CTR_DRBG: drbg_ctr_init().
250 * (2) HMAC_DRBG: drbg_hmac_init().
251 * (3) HASH_DRBG: drbg_hash_init().
253 * The parameters are closely related to the ones described in
254 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
255 * crucial difference: In the NIST standard, all counts are given
256 * in bits, whereas in OpenSSL entropy counts are given in bits
257 * and buffer lengths are given in bytes.
259 * Since this difference has lead to some confusion in the past,
260 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
261 * the 'len' suffix has been added to all buffer sizes for
267 size_t min_entropylen, max_entropylen;
268 size_t min_noncelen, max_noncelen;
269 size_t max_perslen, max_adinlen;
272 * Counts the number of generate requests since the last reseed
273 * (Starts at 1). This value is the reseed_counter as defined in
276 unsigned int reseed_gen_counter;
278 * Maximum number of generate requests until a reseed is required.
279 * This value is ignored if it is zero.
281 unsigned int reseed_interval;
282 /* Stores the time when the last reseeding occurred */
285 * Specifies the maximum time interval (in seconds) between reseeds.
286 * This value is ignored if it is zero.
288 time_t reseed_time_interval;
290 * Counts the number of reseeds since instantiation.
291 * This value is ignored if it is zero.
293 * This counter is used only for seed propagation from the <master> DRBG
294 * to its two children, the <public> and <private> DRBG. This feature is
295 * very special and its sole purpose is to ensure that any randomness which
296 * is added by RAND_add() or RAND_seed() will have an immediate effect on
297 * the output of RAND_bytes() resp. RAND_priv_bytes().
299 TSAN_QUALIFIER unsigned int reseed_prop_counter;
300 unsigned int reseed_next_counter;
305 /* Application data, mainly used in the KATs. */
306 CRYPTO_EX_DATA ex_data;
308 /* Implementation specific data */
315 /* Implementation specific methods */
316 RAND_DRBG_METHOD *meth;
318 /* Callback functions. See comments in rand_lib.c */
319 RAND_DRBG_get_entropy_fn get_entropy;
320 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
321 RAND_DRBG_get_nonce_fn get_nonce;
322 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
325 /* The global RAND method, and the global buffer and DRBG instance. */
326 extern RAND_METHOD rand_meth;
329 * A "generation count" of forks. Incremented in the child process after a
330 * fork. Since rand_fork_count is increment-only, and only ever written to in
331 * the child process of the fork, which is guaranteed to be single-threaded, no
332 * locking is needed for normal (read) accesses; the rest of pthread fork
333 * processing is assumed to introduce the necessary memory barriers. Sibling
334 * children of a given parent will produce duplicate values, but this is not
335 * problematic because the reseeding process pulls input from the system CSPRNG
336 * and/or other global sources, so the siblings will end up generating
337 * different output streams.
339 extern int rand_fork_count;
342 int rand_drbg_restart(RAND_DRBG *drbg,
343 const unsigned char *buffer, size_t len, size_t entropy);
344 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
346 int rand_drbg_lock(RAND_DRBG *drbg);
347 int rand_drbg_unlock(RAND_DRBG *drbg);
348 int rand_drbg_enable_locking(RAND_DRBG *drbg);
351 /* initializes the DRBG implementation */
352 int drbg_ctr_init(RAND_DRBG *drbg);
353 int drbg_hash_init(RAND_DRBG *drbg);
354 int drbg_hmac_init(RAND_DRBG *drbg);
357 * Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
358 * These need to be exposed for the unit tests.
360 int rand_crngt_get_entropy_cb(OPENSSL_CTX *ctx, RAND_POOL *pool,
361 unsigned char *buf, unsigned char *md,
362 unsigned int *md_size);
363 extern int (*crngt_get_entropy)(OPENSSL_CTX *ctx, RAND_POOL *pool,
364 unsigned char *buf, unsigned char *md,
365 unsigned int *md_size);