| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | RAND_set_rand_method, RAND_get_rand_method, RAND_OpenSSL - select RAND method
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/rand.h>
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| 10 |
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| 11 | RAND_METHOD *RAND_OpenSSL(void);
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| 12 |
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| 13 | int RAND_set_rand_method(const RAND_METHOD *meth);
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| 14 |
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| 15 | const RAND_METHOD *RAND_get_rand_method(void);
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| 16 |
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| 17 | =head1 DESCRIPTION
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| 18 |
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| 19 | A B<RAND_METHOD> specifies the functions that OpenSSL uses for random number
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| 20 | generation.
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| 21 |
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| 22 | RAND_OpenSSL() returns the default B<RAND_METHOD> implementation by OpenSSL.
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| 23 | This implementation ensures that the PRNG state is unique for each thread.
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| 24 |
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| 25 | If an B<ENGINE> is loaded that provides the RAND API, however, it will
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| 26 | be used instead of the method returned by RAND_OpenSSL().
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| 27 |
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| 28 | RAND_set_rand_method() makes B<meth> the method for PRNG use. If an
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| 29 | ENGINE was providing the method, it will be released first.
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| 30 |
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| 31 | RAND_get_rand_method() returns a pointer to the current B<RAND_METHOD>.
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| 32 |
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| 33 | =head1 THE RAND_METHOD STRUCTURE
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| 34 |
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| 35 | typedef struct rand_meth_st {
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| 36 | int (*seed)(const void *buf, int num);
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| 37 | int (*bytes)(unsigned char *buf, int num);
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| 38 | void (*cleanup)(void);
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| 39 | int (*add)(const void *buf, int num, double entropy);
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| 40 | int (*pseudorand)(unsigned char *buf, int num);
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| 41 | int (*status)(void);
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| 42 | } RAND_METHOD;
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| 43 |
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| 44 | The fields point to functions that are used by, in order,
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| 45 | RAND_seed(), RAND_bytes(), internal RAND cleanup, RAND_add(), RAND_pseudo_rand()
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| 46 | and RAND_status().
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| 47 | Each pointer may be NULL if the function is not implemented.
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| 48 |
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| 49 | =head1 RETURN VALUES
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| 50 |
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| 51 | RAND_set_rand_method() returns 1 on success and 0 on failure.
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| 52 | RAND_get_rand_method() and RAND_OpenSSL() return pointers to the respective
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| 53 | methods.
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| 54 |
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| 55 | =head1 SEE ALSO
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| 56 |
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| 57 | L<RAND_bytes(3)>,
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| 58 | L<ENGINE_by_id(3)>,
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| 59 | L<RAND(7)>
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| 60 |
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| 61 | =head1 COPYRIGHT
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| 62 |
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| 63 | Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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| 64 |
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| 65 | Licensed under the OpenSSL license (the "License"). You may not use
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| 66 | this file except in compliance with the License. You can obtain a copy
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| 67 | in the file LICENSE in the source distribution or at
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| 68 | L<https://www.openssl.org/source/license.html>.
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| 69 |
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| 70 | =cut
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