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Diffstat (limited to 'openssl-1.1.0h/doc/crypto/RAND_set_rand_method.pod')
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1 files changed, 81 insertions, 0 deletions
diff --git a/openssl-1.1.0h/doc/crypto/RAND_set_rand_method.pod b/openssl-1.1.0h/doc/crypto/RAND_set_rand_method.pod new file mode 100644 index 0000000..02fe90c --- /dev/null +++ b/openssl-1.1.0h/doc/crypto/RAND_set_rand_method.pod @@ -0,0 +1,81 @@ +=pod + +=head1 NAME + +RAND_set_rand_method, RAND_get_rand_method, RAND_OpenSSL - select RAND method + +=head1 SYNOPSIS + + #include <openssl/rand.h> + + 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. + +Initially, the default RAND_METHOD is the OpenSSL internal implementation, as +returned by RAND_OpenSSL(). + +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. + +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<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(3)>, L<engine(3)> + +=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<https://www.openssl.org/source/license.html>. + +=cut |