2 * Copyright 1995-2020 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 OSSL_CRYPTO_RAND_LOCAL_H
11 # define OSSL_CRYPTO_RAND_LOCAL_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 */
39 * Maximum input size for the DRBG (entropy, nonce, personalization string)
41 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
43 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
45 # 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 * Initial allocation minimum.
77 * There is a distinction between the secure and normal allocation minimums.
78 * Ideally, the secure allocation size should be a power of two. The normal
79 * allocation size doesn't have any such restriction.
81 * The secure value is based on 128 bits of secure material, which is 16 bytes.
82 * Typically, the DRBGs will set a minimum larger than this so optimal
83 * allocation ought to take place (for full quality seed material).
85 * The normal value has been chosen by noticing that the rand_drbg_get_nonce
86 * function is usually the largest of the built in allocation (twenty four
87 * bytes and then appending another sixteen bytes). This means the buffer ends
88 * with 40 bytes. The value of forty eight is comfortably above this which
89 * allows some slack in the platform specific values used.
91 # define RAND_POOL_MIN_ALLOCATION(secure) ((secure) ? 16 : 48)
93 /* DRBG status values */
94 typedef enum drbg_status_e {
102 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
103 const unsigned char *ent,
105 const unsigned char *nonce,
107 const unsigned char *pers,
110 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
111 const unsigned char *ent,
113 const unsigned char *adin,
115 /* generate output */
116 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
119 const unsigned char *adin,
122 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
129 typedef struct rand_drbg_method_st {
130 RAND_DRBG_instantiate_fn instantiate;
131 RAND_DRBG_reseed_fn reseed;
132 RAND_DRBG_generate_fn generate;
133 RAND_DRBG_uninstantiate_fn uninstantiate;
138 * The state of a DRBG AES-CTR.
140 typedef struct rand_drbg_ctr_st {
141 EVP_CIPHER_CTX *ctx_ecb;
142 EVP_CIPHER_CTX *ctx_ctr;
143 EVP_CIPHER_CTX *ctx_df;
144 const EVP_CIPHER *cipher_ecb;
145 const EVP_CIPHER *cipher_ctr;
149 /* Temporary block storage used by ctr_df */
150 unsigned char bltmp[16];
152 unsigned char KX[48];
157 * The 'random pool' acts as a dumb container for collecting random
158 * input from various entropy sources. The pool has no knowledge about
159 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
160 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
161 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
162 * 4) cleanup the random pool again.
164 * The random pool contains no locking mechanism because its scope and
165 * lifetime is intended to be restricted to a single stack frame.
167 struct rand_pool_st {
168 unsigned char *buffer; /* points to the beginning of the random pool */
169 size_t len; /* current number of random bytes contained in the pool */
171 int attached; /* true pool was attached to existing buffer */
172 int secure; /* 1: allocated on the secure heap, 0: otherwise */
174 size_t min_len; /* minimum number of random bytes requested */
175 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
176 size_t alloc_len; /* current number of bytes allocated */
177 size_t entropy; /* current entropy count in bits */
178 size_t entropy_requested; /* requested entropy count in bits */
182 * The state of all types of DRBGs, even though we only have CTR mode
185 struct rand_drbg_st {
188 int secure; /* 1: allocated on the secure heap, 0: otherwise */
189 int type; /* the nid of the underlying algorithm */
191 * Stores the return value of openssl_get_fork_id() as of when we last
192 * reseeded. The DRBG reseeds automatically whenever drbg->fork_id !=
193 * openssl_get_fork_id(). Used to provide fork-safety and reseed this
194 * DRBG in the child process.
197 unsigned short flags; /* various external flags */
200 * The random_data is used by RAND_add()/drbg_add() to attach random
201 * data to the global drbg, such that the rand_drbg_get_entropy() callback
202 * can pull it during instantiation and reseeding. This is necessary to
203 * reconcile the different philosophies of the RAND and the RAND_DRBG
204 * with respect to how randomness is added to the RNG during reseeding
207 struct rand_pool_st *seed_pool;
210 * Auxiliary pool for additional data.
212 struct rand_pool_st *adin_pool;
215 * The following parameters are setup by the per-type "init" function.
217 * Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
219 * The parameters are closely related to the ones described in
220 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
221 * crucial difference: In the NIST standard, all counts are given
222 * in bits, whereas in OpenSSL entropy counts are given in bits
223 * and buffer lengths are given in bytes.
225 * Since this difference has lead to some confusion in the past,
226 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
227 * the 'len' suffix has been added to all buffer sizes for
233 size_t min_entropylen, max_entropylen;
234 size_t min_noncelen, max_noncelen;
235 size_t max_perslen, max_adinlen;
237 /* Counts the number of generate requests since the last reseed. */
238 unsigned int generate_counter;
240 * Maximum number of generate requests until a reseed is required.
241 * This value is ignored if it is zero.
243 unsigned int reseed_interval;
244 /* Stores the time when the last reseeding occurred */
247 * Specifies the maximum time interval (in seconds) between reseeds.
248 * This value is ignored if it is zero.
250 time_t reseed_time_interval;
253 * Enables reseed propagation (see following comment)
255 unsigned int enable_reseed_propagation;
258 * Counts the number of reseeds since instantiation.
259 * This value is ignored if enable_reseed_propagation is zero.
261 * This counter is used only for seed propagation from the <master> DRBG
262 * to its two children, the <public> and <private> DRBG. This feature is
263 * very special and its sole purpose is to ensure that any randomness which
264 * is added by RAND_add() or RAND_seed() will have an immediate effect on
265 * the output of RAND_bytes() resp. RAND_priv_bytes().
267 TSAN_QUALIFIER unsigned int reseed_counter;
272 /* Application data, mainly used in the KATs. */
273 CRYPTO_EX_DATA ex_data;
275 /* Implementation specific data (currently only one implementation) */
280 /* Implementation specific methods */
281 RAND_DRBG_METHOD *meth;
283 /* Callback functions. See comments in rand_lib.c */
284 RAND_DRBG_get_entropy_fn get_entropy;
285 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
286 RAND_DRBG_get_nonce_fn get_nonce;
287 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
290 /* The global RAND method, and the global buffer and DRBG instance. */
291 extern RAND_METHOD rand_meth;
294 int rand_drbg_restart(RAND_DRBG *drbg,
295 const unsigned char *buffer, size_t len, size_t entropy);
296 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
298 int rand_drbg_lock(RAND_DRBG *drbg);
299 int rand_drbg_unlock(RAND_DRBG *drbg);
300 int rand_drbg_enable_locking(RAND_DRBG *drbg);
303 /* initializes the AES-CTR DRBG implementation */
304 int drbg_ctr_init(RAND_DRBG *drbg);