=pod =head1 NAME RAND_set_rand_method, RAND_get_rand_method, RAND_OpenSSL - select RAND method =head1 SYNOPSIS #include 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 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 API calls. Initially, the default RAND_METHOD is the OpenSSL internal implementation, as returned by RAND_OpenSSL(). RAND_set_default_method() makes B the method for PRNG use. B: This is true only whilst no ENGINE has been set as a default for RAND, so this function is no longer recommended. 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. =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); } RAND_METHOD; The components point to method implementations used by (or called 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. =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 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, L =head1 COPYRIGHT Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (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. =cut