#include <openssl/rand.h>
+ RAND_METHOD *RAND_OpenSSL(void);
+
void RAND_set_rand_method(const RAND_METHOD *meth);
const RAND_METHOD *RAND_get_rand_method(void);
- RAND_METHOD *RAND_OpenSSL(void);
-
=head1 DESCRIPTION
A B<RAND_METHOD> specifies the functions that OpenSSL uses for random number
-generation. By modifying the method, alternative implementations such as
-hardware RNGs may be used. IMPORTANT: See the NOTES section for important
-information about how these RAND API functions are affected by the use of
-B<ENGINE> API calls.
+generation.
-Initially, the default RAND_METHOD is the OpenSSL internal implementation, as
-returned by RAND_OpenSSL().
+RAND_OpenSSL() returns the default B<RAND_METHOD> implementation by OpenSSL.
+This implementation ensures that the PRNG state is unique for each thread.
-RAND_set_default_method() makes B<meth> the method for PRNG use. B<NB>: This is
-true only whilst no ENGINE has been set as a default for RAND, so this function
-is no longer recommended.
+If an B<ENGINE> is loaded that provides the RAND API, however, it will
+be used instead of the method returned by RAND_OpenSSL().
-RAND_get_default_method() returns a pointer to the current RAND_METHOD.
-However, the meaningfulness of this result is dependent on whether the ENGINE
-API is being used, so this function is no longer recommended.
+RAND_set_rand_method() makes B<meth> the method for PRNG use. If an
+ENGINE was providing the method, it will be released first.
+
+RAND_get_rand_method() returns a pointer to the current B<RAND_METHOD>.
=head1 THE RAND_METHOD STRUCTURE
- typedef struct rand_meth_st
- {
- void (*seed)(const void *buf, int num);
- int (*bytes)(unsigned char *buf, int num);
- void (*cleanup)(void);
- void (*add)(const void *buf, int num, int entropy);
- int (*pseudorand)(unsigned char *buf, int num);
- int (*status)(void);
+ typedef struct rand_meth_st {
+ void (*seed)(const void *buf, int num);
+ int (*bytes)(unsigned char *buf, int num);
+ void (*cleanup)(void);
+ void (*add)(const void *buf, int num, int randomness);
+ int (*pseudorand)(unsigned char *buf, int num);
+ int (*status)(void);
} RAND_METHOD;
-The components point to method implementations used by (or called by), in order,
+The fields point to functions that are used by, in order,
RAND_seed(), RAND_bytes(), internal RAND cleanup, RAND_add(), RAND_pseudo_rand()
and RAND_status().
-Each component may be NULL if the function is not implemented.
+Each pointer may be NULL if the function is not implemented.
=head1 RETURN VALUES
RAND_set_rand_method() returns no value. RAND_get_rand_method() and
RAND_OpenSSL() return pointers to the respective methods.
-=head1 NOTES
-
-RAND_METHOD implementations are grouped together with other
-algorithmic APIs (eg. RSA_METHOD, EVP_CIPHER, etc) in B<ENGINE> modules. If a
-default ENGINE is specified for RAND functionality using an ENGINE API function,
-that will override any RAND defaults set using the RAND API (ie.
-RAND_set_rand_method()). For this reason, the ENGINE API is the recommended way
-to control default implementations for use in RAND and other cryptographic
-algorithms.
-
=head1 SEE ALSO
-L<RAND_bytes(3)>, L<ENGINE_by_id(3)>
+L<RAND_bytes(3)>,
+L<ENGINE_by_id(3)>,
+L<RAND(7)>
=head1 COPYRIGHT
-Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
-Licensed under the OpenSSL license (the "License"). You may not use
+Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.