1BN_RAND(3) OpenSSL BN_RAND(3)
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6 BN_rand, BN_priv_rand, BN_pseudo_rand, BN_rand_range,
7 BN_priv_rand_range, BN_pseudo_rand_range - generate pseudo-random
8 number
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11 #include <openssl/bn.h>
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13 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
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15 int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);
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17 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
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19 int BN_rand_range(BIGNUM *rnd, BIGNUM *range);
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21 int BN_priv_rand_range(BIGNUM *rnd, BIGNUM *range);
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23 int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);
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26 BN_rand() generates a cryptographically strong pseudo-random number of
27 bits in length and stores it in rnd. If bits is less than zero, or too
28 small to accommodate the requirements specified by the top and bottom
29 parameters, an error is returned. The top parameters specifies
30 requirements on the most significant bit of the generated number. If
31 it is BN_RAND_TOP_ANY, there is no constraint. If it is
32 BN_RAND_TOP_ONE, the top bit must be one. If it is BN_RAND_TOP_TWO,
33 the two most significant bits of the number will be set to 1, so that
34 the product of two such random numbers will always have 2*bits length.
35 If bottom is BN_RAND_BOTTOM_ODD, the number will be odd; if it is
36 BN_RAND_BOTTOM_ANY it can be odd or even. If bits is 1 then top cannot
37 also be BN_RAND_FLG_TOPTWO.
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39 BN_rand_range() generates a cryptographically strong pseudo-random
40 number rnd in the range 0 <= rnd < range.
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42 BN_priv_rand() and BN_priv_rand_range() have the same semantics as
43 BN_rand() and BN_rand_range() respectively. They are intended to be
44 used for generating values that should remain private, and mirror the
45 same difference between RAND_bytes(3) and RAND_priv_bytes(3).
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48 Always check the error return value of these functions and do not take
49 randomness for granted: an error occurs if the CSPRNG has not been
50 seeded with enough randomness to ensure an unpredictable byte sequence.
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53 The functions return 1 on success, 0 on error. The error codes can be
54 obtained by ERR_get_error(3).
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57 ERR_get_error(3), RAND_add(3), RAND_bytes(3), RAND_priv_bytes(3),
58 RAND(7), RAND_DRBG(7)
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61 • Starting with OpenSSL release 1.1.0, BN_pseudo_rand() has been
62 identical to BN_rand() and BN_pseudo_rand_range() has been identical
63 to BN_rand_range(). The "pseudo" functions should not be used and
64 may be deprecated in a future release.
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66 • The BN_priv_rand() and BN_priv_rand_range() functions were added in
67 OpenSSL 1.1.1.
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70 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
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72 Licensed under the OpenSSL license (the "License"). You may not use
73 this file except in compliance with the License. You can obtain a copy
74 in the file LICENSE in the source distribution or at
75 <https://www.openssl.org/source/license.html>.
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791.1.1l 2021-09-15 BN_RAND(3)