BN_rand, BN_priv_rand, BN_pseudo_rand, BN_rand_range, BN_priv_rand_range, BN_pseudo_rand_range - generate pseudo-random number
#include <openssl/bn.h>
int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);
int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
int BN_rand_range(BIGNUM *rnd, BIGNUM *range);
int BN_priv_rand_range(BIGNUM *rnd, BIGNUM *range);
int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);
BN_rand() generates a cryptographically strong pseudo-random number of
bits in length and stores it in rnd.
If bits is less than zero, or too small to
accommodate the requirements specified by the top and bottom
parameters, an error is returned.
The top parameters specifies
requirements on the most significant bit of the generated number.
If it is BN_RAND_TOP_ANY, there is no constraint.
If it is BN_RAND_TOP_ONE, the top bit must be one.
If it is BN_RAND_TOP_TWO, the two most significant bits of
the number will be set to 1, so that the product of two such random
numbers will always have 2*bits length.
If bottom is BN_RAND_BOTTOM_ODD, the number will be odd; if it
is BN_RAND_BOTTOM_ANY it can be odd or even.
If bits is 1 then top cannot also be BN_RAND_FLG_TOPTWO.
BN_rand_range() generates a cryptographically strong pseudo-random
number rnd in the range 0 <= rnd < range.
BN_priv_rand() and BN_priv_rand_range() have the same semantics as
BN_rand() and BN_rand_range() respectively. They are intended to be
used for generating values that should remain private, and mirror the
same difference between RAND_bytes(3) and RAND_priv_bytes(3).
Always check the error return value of these functions and do not take randomness for granted: an error occurs if the CSPRNG has not been seeded with enough randomness to ensure an unpredictable byte sequence.
The functions return 1 on success, 0 on error. The error codes can be obtained by ERR_get_error(3).
ERR_get_error(3), RAND_add(3), RAND_bytes(3), RAND_priv_bytes(3), RAND(7), RAND_DRBG(7)
Starting with OpenSSL release 1.1.0, BN_pseudo_rand() has been identical
to BN_rand() and BN_pseudo_rand_range() has been identical to
BN_rand_range().
The "pseudo" functions should not be used and may be deprecated in
a future release.
The
BN_priv_rand() and BN_priv_rand_range() functions were added in OpenSSL 1.1.1.
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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 https://www.openssl.org/source/license.html.