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,
8 EVP_RAND_nonce, EVP_RAND_enable_locking,
9 EVP_RAND_verify_zeroization, EVP_RAND_strength, EVP_RAND_state,
10 EVP_RAND_provider, EVP_RAND_CTX_rand, EVP_RAND_is_a, EVP_RAND_number,
11 EVP_RAND_name, EVP_RAND_names_do_all, EVP_RAND_get_ctx_params,
12 EVP_RAND_set_ctx_params, EVP_RAND_do_all_provided, EVP_RAND_get_params,
13 EVP_RAND_gettable_ctx_params, EVP_RAND_settable_ctx_params,
14 EVP_RAND_CTX_gettable_params, EVP_RAND_CTX_settable_params,
15 EVP_RAND_gettable_params, EVP_RAND_STATE_UNINITIALISED, EVP_RAND_STATE_READY,
16 EVP_RAND_STATE_ERROR - EVP RAND routines
20 #include <openssl/evp.h>
22 typedef struct evp_rand_st EVP_RAND;
23 typedef struct evp_rand_ctx_st EVP_RAND_CTX;
25 EVP_RAND *EVP_RAND_fetch(OSSL_LIB_CTX *libctx, const char *algorithm,
26 const char *properties);
27 int EVP_RAND_up_ref(EVP_RAND *rand);
28 void EVP_RAND_free(EVP_RAND *rand);
29 EVP_RAND_CTX *EVP_RAND_CTX_new(EVP_RAND *rand, EVP_RAND_CTX *parent);
30 void EVP_RAND_CTX_free(EVP_RAND_CTX *ctx);
31 EVP_RAND *EVP_RAND_CTX_rand(EVP_RAND_CTX *ctx);
32 int EVP_RAND_get_params(EVP_RAND *rand, OSSL_PARAM params[]);
33 int EVP_RAND_get_ctx_params(EVP_RAND_CTX *ctx, OSSL_PARAM params[]);
34 int EVP_RAND_set_ctx_params(EVP_RAND_CTX *ctx, const OSSL_PARAM params[]);
35 const OSSL_PARAM *EVP_RAND_gettable_params(const EVP_RAND *rand);
36 const OSSL_PARAM *EVP_RAND_gettable_ctx_params(const EVP_RAND *rand);
37 const OSSL_PARAM *EVP_RAND_settable_ctx_params(const EVP_RAND *rand);
38 const OSSL_PARAM *EVP_RAND_CTX_gettable_params(EVP_RAND_CTX *ctx);
39 const OSSL_PARAM *EVP_RAND_CTX_settable_params(EVP_RAND_CTX *ctx);
40 int EVP_RAND_number(const EVP_RAND *rand);
41 const char *EVP_RAND_name(const EVP_RAND *rand);
42 int EVP_RAND_is_a(const EVP_RAND *rand, const char *name);
43 const OSSL_PROVIDER *EVP_RAND_provider(const EVP_RAND *rand);
44 void EVP_RAND_do_all_provided(OSSL_LIB_CTX *libctx,
45 void (*fn)(EVP_RAND *rand, void *arg),
47 int EVP_RAND_names_do_all(const EVP_RAND *rand,
48 void (*fn)(const char *name, void *data),
51 int EVP_RAND_instantiate(EVP_RAND_CTX *ctx, unsigned int strength,
52 int prediction_resistance,
53 const unsigned char *pstr, size_t pstr_len,
54 const OSSL_PARAM params[]);
55 int EVP_RAND_uninstantiate(EVP_RAND_CTX *ctx);
56 int EVP_RAND_generate(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen,
57 unsigned int strength, int prediction_resistance,
58 const unsigned char *addin, size_t addin_len);
59 int EVP_RAND_reseed(EVP_RAND_CTX *ctx, int prediction_resistance,
60 const unsigned char *ent, size_t ent_len,
61 const unsigned char *addin, size_t addin_len);
62 int EVP_RAND_nonce(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen);
63 int EVP_RAND_enable_locking(EVP_RAND_CTX *ctx);
64 int EVP_RAND_verify_zeroization(EVP_RAND_CTX *ctx);
65 unsigned int EVP_RAND_strength(EVP_RAND_CTX *ctx);
66 int EVP_RAND_state(EVP_RAND_CTX *ctx);
68 #define EVP_RAND_STATE_UNINITIALISED 0
69 #define EVP_RAND_STATE_READY 1
70 #define EVP_RAND_STATE_ERROR 2
74 The EVP RAND routines are a high-level interface to random number generators
75 both deterministic and not.
76 If you just want to generate random bytes then you don't need to use
77 these functions: just call RAND_bytes() or RAND_priv_bytes().
78 If you want to do more, these calls should be used instead of the older
79 RAND and RAND_DRBG functions.
81 After creating a B<EVP_RAND_CTX> for the required algorithm using
82 EVP_RAND_CTX_new(), inputs to the algorithm are supplied either by
83 passing them as part of the EVP_RAND_instantiate() call or using calls to
84 EVP_RAND_set_ctx_params() before calling EVP_RAND_instantiate(). Finally,
85 call EVP_RAND_generate() to produce cryptographically secure random bytes.
89 B<EVP_RAND> is a type that holds the implementation of a RAND.
91 B<EVP_RAND_CTX> is a context type that holds the algorithm inputs.
92 B<EVP_RAND_CTX> structures are reference counted.
94 =head2 Algorithm implementation fetching
96 EVP_RAND_fetch() fetches an implementation of a RAND I<algorithm>, given
97 a library context I<libctx> and a set of I<properties>.
98 See L<provider(7)/Fetching algorithms> for further information.
100 The returned value must eventually be freed with
103 EVP_RAND_up_ref() increments the reference count of an already fetched
106 EVP_RAND_free() frees a fetched algorithm.
107 NULL is a valid parameter, for which this function is a no-op.
109 =head2 Context manipulation functions
111 EVP_RAND_CTX_new() creates a new context for the RAND implementation I<rand>.
112 If not NULL, I<parent> specifies the seed source for this implementation.
113 Not all random number generators need to have a seed source specified.
114 If a parent is required, a NULL I<parent> will utilise the operating
115 system entropy sources.
116 It is recommended to minimise the number of random number generators that
117 rely on the operating system for their randomness because this is often scarce.
119 EVP_RAND_CTX_free() frees up the context I<ctx>. If I<ctx> is NULL, nothing
122 EVP_RAND_CTX_rand() returns the B<EVP_RAND> associated with the context
125 =head2 Random Number Generator Functions
127 EVP_RAND_instantiate() processes any parameters in I<params> and
128 then instantiates the RAND I<ctx> with a minimum security strength
129 of <strength> and personalisation string I<pstr> of length <pstr_len>.
130 If I<prediction_resistance> is specified, fresh entropy from a live source
131 will be sought. This call operates as per NIST SP 800-90A and SP 800-90C.
133 EVP_RAND_uninstantiate() uninstantiates the RAND I<ctx> as per
134 NIST SP 800-90A and SP 800-90C. Subsequent to this call, the RAND cannot
135 be used to generate bytes. It can only be freed or instantiated again.
137 EVP_RAND_generate() produces random bytes from the RAND I<ctx> with the
138 additional input I<addin> of length I<addin_len>. The bytes
139 produced will meet the security I<strength>.
140 If I<prediction_resistance> is specified, fresh entropy from a live source
141 will be sought. This call operates as per NIST SP 800-90A and SP 800-90C.
143 EVP_RAND_reseed() reseeds the RAND with new entropy.
144 Entropy I<ent> of length I<ent_len> bytes can be supplied as can additional
145 input I<addin> of length I<addin_len> bytes. In the FIPS provider, both are
146 treated as additional input as per NIST SP-800-90Ar1, Sections 9.1 and 9.2.
147 Additional seed material is also drawn from the RAND's parent or the
148 operating system. If I<prediction_resistance> is specified, fresh entropy
149 from a live source will be sought. This call operates as per NIST SP 800-90A
152 EVP_RAND_nonce() creates a nonce in I<out> of maximum length I<outlen>
153 bytes from the RAND I<ctx>. The function returns the length of the generated
154 nonce. If I<out> is NULL, the length is still returned but no generation
155 takes place. This allows a caller to dynamically allocate a buffer of the
158 EVP_RAND_enable_locking() enables locking for the RAND I<ctx> and all of
159 its parents. After this I<ctx> will operate in a thread safe manner, albeit
160 more slowly. This function is not itself thread safe if called with the same
161 I<ctx> from multiple threads. Typically locking should be enabled before a
162 I<ctx> is shared across multiple threads.
164 EVP_RAND_get_params() retrieves details about the implementation
166 The set of parameters given with I<params> determine exactly what
167 parameters should be retrieved.
168 Note that a parameter that is unknown in the underlying context is
171 EVP_RAND_get_ctx_params() retrieves chosen parameters, given the
172 context I<ctx> and its underlying context.
173 The set of parameters given with I<params> determine exactly what
174 parameters should be retrieved.
175 Note that a parameter that is unknown in the underlying context is
178 EVP_RAND_set_ctx_params() passes chosen parameters to the underlying
179 context, given a context I<ctx>.
180 The set of parameters given with I<params> determine exactly what
181 parameters are passed down.
182 Note that a parameter that is unknown in the underlying context is
184 Also, what happens when a needed parameter isn't passed down is
185 defined by the implementation.
187 EVP_RAND_gettable_params() returns an B<OSSL_PARAM> array that describes
188 the retrievable and settable parameters. EVP_RAND_gettable_params() returns
189 parameters that can be used with EVP_RAND_get_params(). See L<OSSL_PARAM(3)>
190 for the use of B<OSSL_PARAM> as a parameter descriptor.
192 EVP_RAND_gettable_ctx_params() and EVP_RAND_CTX_gettable_params() return
193 constant B<OSSL_PARAM> arrays that describe the retrievable parameters that
194 can be used with EVP_RAND_CTX_get_params(). EVP_RAND_gettable_ctx_params()
195 returns the parameters that can be retrieved from the algorithm, whereas
196 EVP_RAND_CTX_gettable_params() returns the parameters that can be retrieved
197 in the context's current state. See L<OSSL_PARAM(3)> for the use of
198 B<OSSL_PARAM> as a parameter descriptor.
200 EVP_RAND_settable_ctx_params() and EVP_RAND_CTX_settable_params() return
201 constant B<OSSL_PARAM> arrays that describe the settable parameters that
202 can be used with EVP_RAND_CTX_set_params(). EVP_RAND_settable_ctx_params()
203 returns the parameters that can be retrieved from the algorithm, whereas
204 EVP_RAND_CTX_settable_params() returns the parameters that can be retrieved
205 in the context's current state. See L<OSSL_PARAM(3)> for the use of
206 B<OSSL_PARAM> as a parameter descriptor.
208 =head2 Information functions
210 EVP_RAND_strength() returns the security strength of the RAND I<ctx>.
212 EVP_RAND_state() returns the current state of the RAND I<ctx>.
213 States defined by the OpenSSL RNGs are:
219 EVP_RAND_STATE_UNINITIALISED: this RNG is currently uninitialised.
220 The instantiate call will change this to the ready state.
224 EVP_RAND_STATE_READY: this RNG is currently ready to generate output.
228 EVP_RAND_STATE_ERROR: this RNG is in an error state.
232 EVP_RAND_is_a() returns 1 if I<rand> is an implementation of an
233 algorithm that's identifiable with I<name>, otherwise 0.
235 EVP_RAND_provider() returns the provider that holds the implementation
236 of the given I<rand>.
238 EVP_RAND_do_all_provided() traverses all RAND implemented by all activated
239 providers in the given library context I<libctx>, and for each of the
240 implementations, calls the given function I<fn> with the implementation method
241 and the given I<arg> as argument.
243 EVP_RAND_number() returns the internal dynamic number assigned to
246 EVP_RAND_name() returns the canonical name of I<rand>.
248 EVP_RAND_names_do_all() traverses all names for I<rand>, and calls
249 I<fn> with each name and I<data>.
251 EVP_RAND_verify_zeroization() confirms if the internal DRBG state is
252 currently zeroed. This is used by the FIPS provider to support the mandatory
257 The standard parameter names are:
261 =item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
263 Returns the state of the random number generator.
265 =item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
267 Returns the bit strength of the random number generator.
271 For rands that are also deterministic random bit generators (DRBGs), these
272 additional parameters are recognised. Not all
273 parameters are relevant to, or are understood by all DRBG rands:
277 =item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
279 Reads or set the number of generate requests before reseeding the
282 =item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
284 Reads or set the number of elapsed seconds before reseeding the
287 =item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
289 Specifies the maximum number of bytes that can be generated in a single
290 call to OSSL_FUNC_rand_generate.
292 =item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
294 =item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
296 Specify the minimum and maximum number of bytes of random material that
297 can be used to seed the DRBG.
299 =item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
301 =item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
303 Specify the minimum and maximum number of bytes of nonce that can be used to
306 =item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
308 =item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
310 Specify the minimum and maximum number of bytes of personalisation string
311 that can be used with the DRBG.
313 =item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
315 Specifies the number of times the DRBG has been seeded or reseeded.
317 =item "properties" (B<OSSL_RAND_PARAM_PROPERTIES>) <UTF8 string>
319 =item "mac" (B<OSSL_RAND_PARAM_MAC>) <UTF8 string>
321 =item "digest" (B<OSSL_RAND_PARAM_DIGEST>) <UTF8 string>
323 =item "cipher" (B<OSSL_RAND_PARAM_CIPHER>) <UTF8 string>
325 For RAND implementations that use an underlying computation MAC, digest or
326 cipher, these parameters set what the algorithm should be.
328 The value is always the name of the intended algorithm,
329 or the properties in the case of B<OSSL_RAND_PARAM_PROPERTIES>.
335 An B<EVP_RAND_CTX> needs to have locking enabled if it acts as the parent of
336 more than one child and the children can be accessed concurrently. This must
337 be done by explicitly calling EVP_RAND_enable_locking().
339 The RAND life-cycle is described in L<life_cycle-rand(7)>. In the future,
340 the transitions described there will be enforced. When this is done, it will
341 not be considered a breaking change to the API.
345 EVP_RAND_fetch() returns a pointer to a newly fetched B<EVP_RAND>, or
346 NULL if allocation failed.
348 EVP_RAND_provider() returns a pointer to the provider for the RAND, or
351 EVP_RAND_CTX_rand() returns a pointer to the B<EVP_RAND> associated with the
354 EVP_RAND_name() returns the name of the random number generation algorithm.
356 EVP_RAND_number() returns the provider specific identification number
357 for the specified algorithm.
359 EVP_RAND_up_ref() returns 1 on success, 0 on error.
361 EVP_RAND_names_do_all() returns 1 if the callback was called for all names. A
362 return value of 0 means that the callback was not called for any names.
364 EVP_RAND_CTX_new() returns either the newly allocated
365 B<EVP_RAND_CTX> structure or NULL if an error occurred.
367 EVP_RAND_CTX_free() does not return a value.
369 EVP_RAND_nonce() returns the length of the nonce.
371 EVP_RAND_strength() returns the strength of the random number generator in bits.
373 EVP_RAND_gettable_params(), EVP_RAND_gettable_ctx_params() and
374 EVP_RAND_settable_ctx_params() return an array of OSSL_PARAMs.
376 EVP_RAND_verify_zeroization() returns 1 if the internal DRBG state is
377 currently zeroed, and 0 if not.
379 The remaining functions return 1 for success and 0 or a negative value for
385 L<EVP_RAND-CTR-DRBG(7)>,
386 L<EVP_RAND-HASH-DRBG(7)>,
387 L<EVP_RAND-HMAC-DRBG(7)>,
388 L<EVP_RAND-TEST-RAND(7)>,
390 L<life_cycle-rand(7)>
394 This functionality was added to OpenSSL 3.0.
398 Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
400 Licensed under the Apache License 2.0 (the "License"). You may not use
401 this file except in compliance with the License. You can obtain a copy
402 in the file LICENSE in the source distribution or at
403 L<https://www.openssl.org/source/license.html>.