5 EVP_RAND, EVP_RAND_fetch, EVP_RAND_free, EVP_RAND_up_ref, EVP_RAND_CTX,
6 EVP_RAND_CTX_new, EVP_RAND_CTX_free, EVP_RAND_instantiate,
7 EVP_RAND_uninstantiate, EVP_RAND_generate, EVP_RAND_reseed, EVP_RAND_nonce,
8 EVP_RAND_enable_locking, EVP_RAND_verify_zeroization, EVP_RAND_get_strength,
10 EVP_RAND_get0_provider, EVP_RAND_CTX_get0_rand, EVP_RAND_is_a,
11 EVP_RAND_get0_name, EVP_RAND_names_do_all,
12 EVP_RAND_get0_description,
13 EVP_RAND_CTX_get_params,
14 EVP_RAND_CTX_set_params, EVP_RAND_do_all_provided, EVP_RAND_get_params,
15 EVP_RAND_gettable_ctx_params, EVP_RAND_settable_ctx_params,
16 EVP_RAND_CTX_gettable_params, EVP_RAND_CTX_settable_params,
17 EVP_RAND_gettable_params, EVP_RAND_STATE_UNINITIALISED, EVP_RAND_STATE_READY,
18 EVP_RAND_STATE_ERROR - EVP RAND routines
22 #include <openssl/evp.h>
24 typedef struct evp_rand_st EVP_RAND;
25 typedef struct evp_rand_ctx_st EVP_RAND_CTX;
27 EVP_RAND *EVP_RAND_fetch(OSSL_LIB_CTX *libctx, const char *algorithm,
28 const char *properties);
29 int EVP_RAND_up_ref(EVP_RAND *rand);
30 void EVP_RAND_free(EVP_RAND *rand);
31 EVP_RAND_CTX *EVP_RAND_CTX_new(EVP_RAND *rand, EVP_RAND_CTX *parent);
32 void EVP_RAND_CTX_free(EVP_RAND_CTX *ctx);
33 EVP_RAND *EVP_RAND_CTX_get0_rand(EVP_RAND_CTX *ctx);
34 int EVP_RAND_get_params(EVP_RAND *rand, OSSL_PARAM params[]);
35 int EVP_RAND_CTX_get_params(EVP_RAND_CTX *ctx, OSSL_PARAM params[]);
36 int EVP_RAND_CTX_set_params(EVP_RAND_CTX *ctx, const OSSL_PARAM params[]);
37 const OSSL_PARAM *EVP_RAND_gettable_params(const EVP_RAND *rand);
38 const OSSL_PARAM *EVP_RAND_gettable_ctx_params(const EVP_RAND *rand);
39 const OSSL_PARAM *EVP_RAND_settable_ctx_params(const EVP_RAND *rand);
40 const OSSL_PARAM *EVP_RAND_CTX_gettable_params(EVP_RAND_CTX *ctx);
41 const OSSL_PARAM *EVP_RAND_CTX_settable_params(EVP_RAND_CTX *ctx);
42 const char *EVP_RAND_get0_name(const EVP_RAND *rand);
43 const char *EVP_RAND_get0_description(const EVP_RAND *rand);
44 int EVP_RAND_is_a(const EVP_RAND *rand, const char *name);
45 const OSSL_PROVIDER *EVP_RAND_get0_provider(const EVP_RAND *rand);
46 void EVP_RAND_do_all_provided(OSSL_LIB_CTX *libctx,
47 void (*fn)(EVP_RAND *rand, void *arg),
49 int EVP_RAND_names_do_all(const EVP_RAND *rand,
50 void (*fn)(const char *name, void *data),
53 int EVP_RAND_instantiate(EVP_RAND_CTX *ctx, unsigned int strength,
54 int prediction_resistance,
55 const unsigned char *pstr, size_t pstr_len,
56 const OSSL_PARAM params[]);
57 int EVP_RAND_uninstantiate(EVP_RAND_CTX *ctx);
58 int EVP_RAND_generate(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen,
59 unsigned int strength, int prediction_resistance,
60 const unsigned char *addin, size_t addin_len);
61 int EVP_RAND_reseed(EVP_RAND_CTX *ctx, int prediction_resistance,
62 const unsigned char *ent, size_t ent_len,
63 const unsigned char *addin, size_t addin_len);
64 int EVP_RAND_nonce(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen);
65 int EVP_RAND_enable_locking(EVP_RAND_CTX *ctx);
66 int EVP_RAND_verify_zeroization(EVP_RAND_CTX *ctx);
67 unsigned int EVP_RAND_get_strength(EVP_RAND_CTX *ctx);
68 int EVP_RAND_get_state(EVP_RAND_CTX *ctx);
70 #define EVP_RAND_STATE_UNINITIALISED 0
71 #define EVP_RAND_STATE_READY 1
72 #define EVP_RAND_STATE_ERROR 2
76 The EVP RAND routines are a high-level interface to random number generators
77 both deterministic and not.
78 If you just want to generate random bytes then you don't need to use
79 these functions: just call RAND_bytes() or RAND_priv_bytes().
80 If you want to do more, these calls should be used instead of the older
81 RAND and RAND_DRBG functions.
83 After creating a B<EVP_RAND_CTX> for the required algorithm using
84 EVP_RAND_CTX_new(), inputs to the algorithm are supplied either by
85 passing them as part of the EVP_RAND_instantiate() call or using calls to
86 EVP_RAND_CTX_set_params() before calling EVP_RAND_instantiate(). Finally,
87 call EVP_RAND_generate() to produce cryptographically secure random bytes.
91 B<EVP_RAND> is a type that holds the implementation of a RAND.
93 B<EVP_RAND_CTX> is a context type that holds the algorithm inputs.
94 B<EVP_RAND_CTX> structures are reference counted.
96 =head2 Algorithm implementation fetching
98 EVP_RAND_fetch() fetches an implementation of a RAND I<algorithm>, given
99 a library context I<libctx> and a set of I<properties>.
100 See L<crypto(7)/ALGORITHM FETCHING> for further information.
102 The returned value must eventually be freed with
105 EVP_RAND_up_ref() increments the reference count of an already fetched
108 EVP_RAND_free() frees a fetched algorithm.
109 NULL is a valid parameter, for which this function is a no-op.
111 =head2 Context manipulation functions
113 EVP_RAND_CTX_new() creates a new context for the RAND implementation I<rand>.
114 If not NULL, I<parent> specifies the seed source for this implementation.
115 Not all random number generators need to have a seed source specified.
116 If a parent is required, a NULL I<parent> will utilise the operating
117 system entropy sources.
118 It is recommended to minimise the number of random number generators that
119 rely on the operating system for their randomness because this is often scarce.
121 EVP_RAND_CTX_free() frees up the context I<ctx>. If I<ctx> is NULL, nothing
124 EVP_RAND_CTX_get0_rand() returns the B<EVP_RAND> associated with the context
127 =head2 Random Number Generator Functions
129 EVP_RAND_instantiate() processes any parameters in I<params> and
130 then instantiates the RAND I<ctx> with a minimum security strength
131 of <strength> and personalisation string I<pstr> of length <pstr_len>.
132 If I<prediction_resistance> is specified, fresh entropy from a live source
133 will be sought. This call operates as per NIST SP 800-90A and SP 800-90C.
135 EVP_RAND_uninstantiate() uninstantiates the RAND I<ctx> as per
136 NIST SP 800-90A and SP 800-90C. Subsequent to this call, the RAND cannot
137 be used to generate bytes. It can only be freed or instantiated again.
139 EVP_RAND_generate() produces random bytes from the RAND I<ctx> with the
140 additional input I<addin> of length I<addin_len>. The bytes
141 produced will meet the security I<strength>.
142 If I<prediction_resistance> is specified, fresh entropy from a live source
143 will be sought. This call operates as per NIST SP 800-90A and SP 800-90C.
145 EVP_RAND_reseed() reseeds the RAND with new entropy.
146 Entropy I<ent> of length I<ent_len> bytes can be supplied as can additional
147 input I<addin> of length I<addin_len> bytes. In the FIPS provider, both are
148 treated as additional input as per NIST SP-800-90Ar1, Sections 9.1 and 9.2.
149 Additional seed material is also drawn from the RAND's parent or the
150 operating system. If I<prediction_resistance> is specified, fresh entropy
151 from a live source will be sought. This call operates as per NIST SP 800-90A
154 EVP_RAND_nonce() creates a nonce in I<out> of maximum length I<outlen>
155 bytes from the RAND I<ctx>. The function returns the length of the generated
156 nonce. If I<out> is NULL, the length is still returned but no generation
157 takes place. This allows a caller to dynamically allocate a buffer of the
160 EVP_RAND_enable_locking() enables locking for the RAND I<ctx> and all of
161 its parents. After this I<ctx> will operate in a thread safe manner, albeit
162 more slowly. This function is not itself thread safe if called with the same
163 I<ctx> from multiple threads. Typically locking should be enabled before a
164 I<ctx> is shared across multiple threads.
166 EVP_RAND_get_params() retrieves details about the implementation
168 The set of parameters given with I<params> determine exactly what
169 parameters should be retrieved.
170 Note that a parameter that is unknown in the underlying context is
173 EVP_RAND_CTX_get_params() retrieves chosen parameters, given the
174 context I<ctx> and its underlying context.
175 The set of parameters given with I<params> determine exactly what
176 parameters should be retrieved.
177 Note that a parameter that is unknown in the underlying context is
180 EVP_RAND_CTX_set_params() passes chosen parameters to the underlying
181 context, given a context I<ctx>.
182 The set of parameters given with I<params> determine exactly what
183 parameters are passed down.
184 Note that a parameter that is unknown in the underlying context is
186 Also, what happens when a needed parameter isn't passed down is
187 defined by the implementation.
189 EVP_RAND_gettable_params() returns an B<OSSL_PARAM> array that describes
190 the retrievable and settable parameters. EVP_RAND_gettable_params() returns
191 parameters that can be used with EVP_RAND_get_params(). See L<OSSL_PARAM(3)>
192 for the use of B<OSSL_PARAM> as a parameter descriptor.
194 EVP_RAND_gettable_ctx_params() and EVP_RAND_CTX_gettable_params() return
195 constant B<OSSL_PARAM> arrays that describe the retrievable parameters that
196 can be used with EVP_RAND_CTX_get_params(). EVP_RAND_gettable_ctx_params()
197 returns the parameters that can be retrieved from the algorithm, whereas
198 EVP_RAND_CTX_gettable_params() returns the parameters that can be retrieved
199 in the context's current state. See L<OSSL_PARAM(3)> for the use of
200 B<OSSL_PARAM> as a parameter descriptor.
202 EVP_RAND_settable_ctx_params() and EVP_RAND_CTX_settable_params() return
203 constant B<OSSL_PARAM> arrays that describe the settable parameters that
204 can be used with EVP_RAND_CTX_set_params(). EVP_RAND_settable_ctx_params()
205 returns the parameters that can be retrieved from the algorithm, whereas
206 EVP_RAND_CTX_settable_params() returns the parameters that can be retrieved
207 in the context's current state. See L<OSSL_PARAM(3)> for the use of
208 B<OSSL_PARAM> as a parameter descriptor.
210 =head2 Information functions
212 EVP_RAND_get_strength() returns the security strength of the RAND I<ctx>.
214 EVP_RAND_get_state() returns the current state of the RAND I<ctx>.
215 States defined by the OpenSSL RNGs are:
221 EVP_RAND_STATE_UNINITIALISED: this RNG is currently uninitialised.
222 The instantiate call will change this to the ready state.
226 EVP_RAND_STATE_READY: this RNG is currently ready to generate output.
230 EVP_RAND_STATE_ERROR: this RNG is in an error state.
234 EVP_RAND_is_a() returns 1 if I<rand> is an implementation of an
235 algorithm that's identifiable with I<name>, otherwise 0.
237 EVP_RAND_get0_provider() returns the provider that holds the implementation
238 of the given I<rand>.
240 EVP_RAND_do_all_provided() traverses all RAND implemented by all activated
241 providers in the given library context I<libctx>, and for each of the
242 implementations, calls the given function I<fn> with the implementation method
243 and the given I<arg> as argument.
245 EVP_RAND_get0_name() returns the canonical name of I<rand>.
247 EVP_RAND_names_do_all() traverses all names for I<rand>, and calls
248 I<fn> with each name and I<data>.
250 EVP_RAND_get0_description() returns a description of the rand, meant for
251 display and human consumption. The description is at the discretion of
252 the rand implementation.
254 EVP_RAND_verify_zeroization() confirms if the internal DRBG state is
255 currently zeroed. This is used by the FIPS provider to support the mandatory
260 The standard parameter names are:
264 =item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
266 Returns the state of the random number generator.
268 =item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
270 Returns the bit strength of the random number generator.
274 For rands that are also deterministic random bit generators (DRBGs), these
275 additional parameters are recognised. Not all
276 parameters are relevant to, or are understood by all DRBG rands:
280 =item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
282 Reads or set the number of generate requests before reseeding the
285 =item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
287 Reads or set the number of elapsed seconds before reseeding the
290 =item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
292 Specifies the maximum number of bytes that can be generated in a single
293 call to OSSL_FUNC_rand_generate.
295 =item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
297 =item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
299 Specify the minimum and maximum number of bytes of random material that
300 can be used to seed the DRBG.
302 =item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
304 =item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
306 Specify the minimum and maximum number of bytes of nonce that can be used to
309 =item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
311 =item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
313 Specify the minimum and maximum number of bytes of personalisation string
314 that can be used with the DRBG.
316 =item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
318 Specifies the number of times the DRBG has been seeded or reseeded.
320 =item "properties" (B<OSSL_RAND_PARAM_PROPERTIES>) <UTF8 string>
322 =item "mac" (B<OSSL_RAND_PARAM_MAC>) <UTF8 string>
324 =item "digest" (B<OSSL_RAND_PARAM_DIGEST>) <UTF8 string>
326 =item "cipher" (B<OSSL_RAND_PARAM_CIPHER>) <UTF8 string>
328 For RAND implementations that use an underlying computation MAC, digest or
329 cipher, these parameters set what the algorithm should be.
331 The value is always the name of the intended algorithm,
332 or the properties in the case of B<OSSL_RAND_PARAM_PROPERTIES>.
338 An B<EVP_RAND_CTX> needs to have locking enabled if it acts as the parent of
339 more than one child and the children can be accessed concurrently. This must
340 be done by explicitly calling EVP_RAND_enable_locking().
342 The RAND life-cycle is described in L<life_cycle-rand(7)>. In the future,
343 the transitions described there will be enforced. When this is done, it will
344 not be considered a breaking change to the API.
348 EVP_RAND_fetch() returns a pointer to a newly fetched B<EVP_RAND>, or
349 NULL if allocation failed.
351 EVP_RAND_get0_provider() returns a pointer to the provider for the RAND, or
354 EVP_RAND_CTX_get0_rand() returns a pointer to the B<EVP_RAND> associated
357 EVP_RAND_get0_name() returns the name of the random number generation
360 EVP_RAND_up_ref() returns 1 on success, 0 on error.
362 EVP_RAND_names_do_all() returns 1 if the callback was called for all names. A
363 return value of 0 means that the callback was not called for any names.
365 EVP_RAND_CTX_new() returns either the newly allocated
366 B<EVP_RAND_CTX> structure or NULL if an error occurred.
368 EVP_RAND_CTX_free() does not return a value.
370 EVP_RAND_nonce() returns the length of the nonce.
372 EVP_RAND_get_strength() returns the strength of the random number generator
375 EVP_RAND_gettable_params(), EVP_RAND_gettable_ctx_params() and
376 EVP_RAND_settable_ctx_params() return an array of OSSL_PARAMs.
378 EVP_RAND_verify_zeroization() returns 1 if the internal DRBG state is
379 currently zeroed, and 0 if not.
381 The remaining functions return 1 for success and 0 or a negative value for
387 L<EVP_RAND-CTR-DRBG(7)>,
388 L<EVP_RAND-HASH-DRBG(7)>,
389 L<EVP_RAND-HMAC-DRBG(7)>,
390 L<EVP_RAND-TEST-RAND(7)>,
392 L<life_cycle-rand(7)>
396 This functionality was added to OpenSSL 3.0.
400 Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
402 Licensed under the Apache License 2.0 (the "License"). You may not use
403 this file except in compliance with the License. You can obtain a copy
404 in the file LICENSE in the source distribution or at
405 L<https://www.openssl.org/source/license.html>.