1BN_RAND(3ossl) OpenSSL BN_RAND(3ossl)
2
6 BN_rand_ex, BN_rand, BN_priv_rand_ex, BN_priv_rand, BN_pseudo_rand,
7 BN_rand_range_ex, BN_rand_range, BN_priv_rand_range_ex,
8 BN_priv_rand_range, BN_pseudo_rand_range - generate pseudo-random
9 number
10
12 #include <openssl/bn.h>
13 int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
15 unsigned int strength, BN_CTX *ctx);
16 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
17 int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
19 unsigned int strength, BN_CTX *ctx);
20 int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);
21 int BN_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength,
23 BN_CTX *ctx);
24 int BN_rand_range(BIGNUM *rnd, const BIGNUM *range);
25 int BN_priv_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength,
27 BN_CTX *ctx);
28 int BN_priv_rand_range(BIGNUM *rnd, const BIGNUM *range);
29 The following functions have been deprecated since OpenSSL 3.0, and can
31 be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
32 version value, see openssl_user_macros(7):
33 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
35 int BN_pseudo_rand_range(BIGNUM *rnd, const BIGNUM *range);
36
38 BN_rand_ex() generates a cryptographically strong pseudo-random number
39 of bits in length and security strength at least strength bits using
40 the random number generator for the library context associated with
41 ctx. The function stores the generated data in rnd. The parameter ctx
42 may be NULL in which case the default library context is used. If bits
43 is less than zero, or too small to accommodate the requirements
44 specified by the top and bottom parameters, an error is returned. The
45 top parameters specifies requirements on the most significant bit of
46 the generated number. If it is BN_RAND_TOP_ANY, there is no
47 constraint. If it is BN_RAND_TOP_ONE, the top bit must be one. If it
48 is BN_RAND_TOP_TWO, the two most significant bits of the number will be
49 set to 1, so that the product of two such random numbers will always
50 have 2*bits length. If bottom is BN_RAND_BOTTOM_ODD, the number will
51 be odd; if it is BN_RAND_BOTTOM_ANY it can be odd or even. If bits is
52 1 then top cannot also be BN_RAND_TOP_TWO.
53 BN_rand() is the same as BN_rand_ex() except that the default library
55 context is always used.
56 BN_rand_range_ex() generates a cryptographically strong pseudo-random
58 number rnd, of security strength at least strength bits, in the range 0
59 <= rnd < range using the random number generator for the library
60 context associated with ctx. The parameter ctx may be NULL in which
61 case the default library context is used.
62 BN_rand_range() is the same as BN_rand_range_ex() except that the
64 default library context is always used.
65 BN_priv_rand_ex(), BN_priv_rand(), BN_priv_rand_rand_ex() and
67 BN_priv_rand_range() have the same semantics as BN_rand_ex(),
68 BN_rand(), BN_rand_range_ex() and BN_rand_range() respectively. They
69 are intended to be used for generating values that should remain
70 private, and mirror the same difference between RAND_bytes(3) and
71 RAND_priv_bytes(3).
72
74 Always check the error return value of these functions and do not take
75 randomness for granted: an error occurs if the CSPRNG has not been
76 seeded with enough randomness to ensure an unpredictable byte sequence.
77
79 The functions return 1 on success, 0 on error. The error codes can be
80 obtained by ERR_get_error(3).
81
83 ERR_get_error(3), RAND_add(3), RAND_bytes(3), RAND_priv_bytes(3),
84 RAND(7), EVP_RAND(7)
85
87 • Starting with OpenSSL release 1.1.0, BN_pseudo_rand() has been
88 identical to BN_rand() and BN_pseudo_rand_range() has been identical
89 to BN_rand_range(). The BN_pseudo_rand() and BN_pseudo_rand_range()
90 functions were deprecated in OpenSSL 3.0.
91 • The BN_priv_rand() and BN_priv_rand_range() functions were added in
93 OpenSSL 1.1.1.
94 • The BN_rand_ex(), BN_priv_rand_ex(), BN_rand_range_ex() and
96 BN_priv_rand_range_ex() functions were added in OpenSSL 3.0.
97
99 Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.
100 Licensed under the Apache License 2.0 (the "License"). You may not use
102 this file except in compliance with the License. You can obtain a copy
103 in the file LICENSE in the source distribution or at
104 <https://www.openssl.org/source/license.html>.
1053.1.1 2023-08-31 BN_RAND(3ossl)