| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM assignment
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| 6 | operations
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| 7 |
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| 8 | =head1 SYNOPSIS
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| 9 |
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| 10 | #include <openssl/bn.h>
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| 11 |
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| 12 | void BN_zero(BIGNUM *a);
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| 13 | int BN_one(BIGNUM *a);
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| 14 |
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| 15 | const BIGNUM *BN_value_one(void);
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| 16 |
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| 17 | int BN_set_word(BIGNUM *a, BN_ULONG w);
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| 18 | unsigned BN_ULONG BN_get_word(BIGNUM *a);
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| 19 |
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| 20 | =head1 DESCRIPTION
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| 21 |
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| 22 | B<BN_ULONG> is a macro that will be an unsigned integral type optimized
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| 23 | for the most efficient implementation on the local platform.
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| 24 |
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| 25 | BN_zero(), BN_one() and BN_set_word() set B<a> to the values 0, 1 and
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| 26 | B<w> respectively. BN_zero() and BN_one() are macros.
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| 27 |
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| 28 | BN_value_one() returns a B<BIGNUM> constant of value 1. This constant
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| 29 | is useful for use in comparisons and assignment.
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| 30 |
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| 31 | BN_get_word() returns B<a>, if it can be represented as a B<BN_ULONG>.
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| 32 |
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| 33 | =head1 RETURN VALUES
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| 34 |
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| 35 | BN_get_word() returns the value B<a>, or all-bits-set if B<a> cannot
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| 36 | be represented as a single integer.
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| 37 |
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| 38 | BN_one() and BN_set_word() return 1 on success, 0 otherwise.
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| 39 | BN_value_one() returns the constant.
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| 40 | BN_zero() never fails and returns no value.
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| 41 |
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| 42 | =head1 BUGS
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| 43 |
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| 44 | If a B<BIGNUM> is equal to the value of all-bits-set, it will collide
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| 45 | with the error condition returned by BN_get_word() which uses that
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| 46 | as an error value.
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| 47 |
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| 48 | B<BN_ULONG> should probably be a typedef.
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| 49 |
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| 50 | =head1 SEE ALSO
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| 51 |
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| 52 | L<BN_bn2bin(3)>
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| 53 |
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| 54 | =head1 HISTORY
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| 55 |
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| 56 | In OpenSSL 0.9.8, BN_zero() was changed to not return a value; previous
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| 57 | versions returned an int.
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| 58 |
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| 59 | =head1 COPYRIGHT
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| 60 |
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| 61 | Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
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| 62 |
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| 63 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 64 | this file except in compliance with the License. You can obtain a copy
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| 65 | in the file LICENSE in the source distribution or at
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| 66 | L<https://www.openssl.org/source/license.html>.
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| 67 |
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| 68 | =cut
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