BN_RAND
Section: OpenSSL (3SSL)
Updated: 2024-03-03
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NAME
BN_rand_ex, BN_rand, BN_priv_rand_ex, BN_priv_rand, BN_pseudo_rand,
BN_rand_range_ex, BN_rand_range, BN_priv_rand_range_ex, BN_priv_rand_range,
BN_pseudo_rand_range
- generate pseudo-random number
SYNOPSIS
#include <openssl/bn.h>
int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
unsigned int strength, BN_CTX *ctx);
int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
unsigned int strength, BN_CTX *ctx);
int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);
int BN_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength,
BN_CTX *ctx);
int BN_rand_range(BIGNUM *rnd, const BIGNUM *range);
int BN_priv_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength,
BN_CTX *ctx);
int BN_priv_rand_range(BIGNUM *rnd, const BIGNUM *range);
The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value,
see openssl_user_macros(7):
int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
int BN_pseudo_rand_range(BIGNUM *rnd, const BIGNUM *range);
DESCRIPTION
BN_rand_ex() generates a cryptographically strong pseudo-random
number of bits in length and security strength at least strength bits
using the random number generator for the library context associated with
ctx. The function stores the generated data in rnd. The parameter ctx
may be NULL in which case the default library context is used.
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_TOP_TWO.
BN_rand() is the same as BN_rand_ex() except that the default library context
is always used.
BN_rand_range_ex() generates a cryptographically strong pseudo-random
number rnd, of security strength at least strength bits,
in the range 0 <= rnd < range using the random number
generator for the library context associated with ctx. The parameter ctx
may be NULL in which case the default library context is used.
BN_rand_range() is the same as BN_rand_range_ex() except that the default
library context is always used.
BN_priv_rand_ex(), BN_priv_rand(), BN_priv_rand_rand_ex() and
BN_priv_rand_range() have the same semantics as BN_rand_ex(), BN_rand(),
BN_rand_range_ex() 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).
NOTES
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.
RETURN VALUES
The functions return 1 on success, 0 on error.
The error codes can be obtained by ERR_get_error(3).
SEE ALSO
ERR_get_error(3),
RAND_add(3),
RAND_bytes(3),
RAND_priv_bytes(3),
RAND(7),
EVP_RAND(7)
HISTORY
- •
-
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 BN_pseudo_rand() and BN_pseudo_rand_range() functions were
deprecated in OpenSSL 3.0.
- •
-
The BN_priv_rand() and BN_priv_rand_range() functions were added in
OpenSSL 1.1.1.
- •
-
The BN_rand_ex(), BN_priv_rand_ex(), BN_rand_range_ex() and
BN_priv_rand_range_ex() functions were added in OpenSSL 3.0.
COPYRIGHT
Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.
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
<https://www.openssl.org/source/license.html>.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- NOTES
-
- RETURN VALUES
-
- SEE ALSO
-
- HISTORY
-
- COPYRIGHT
-
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Time: 14:56:47 GMT, May 19, 2024