| 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_CTX_new, BN_CTX_secure_new, BN_CTX_free - allocate and free BN_CTX structures
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/bn.h>
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| 10 |
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| 11 | BN_CTX *BN_CTX_new(void);
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| 12 |
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| 13 | BN_CTX *BN_CTX_secure_new(void);
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| 14 |
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| 15 | void BN_CTX_free(BN_CTX *c);
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| 16 |
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| 17 | =head1 DESCRIPTION
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| 18 |
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| 19 | A B<BN_CTX> is a structure that holds B<BIGNUM> temporary variables used by
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| 20 | library functions. Since dynamic memory allocation to create B<BIGNUM>s
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| 21 | is rather expensive when used in conjunction with repeated subroutine
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| 22 | calls, the B<BN_CTX> structure is used.
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| 23 |
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| 24 | BN_CTX_new() allocates and initializes a B<BN_CTX> structure.
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| 25 | BN_CTX_secure_new() allocates and initializes a B<BN_CTX> structure
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| 26 | but uses the secure heap (see L<CRYPTO_secure_malloc(3)>) to hold the
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| 27 | B<BIGNUM>s.
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| 28 |
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| 29 | BN_CTX_free() frees the components of the B<BN_CTX> and the structure itself.
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| 30 | Since BN_CTX_start() is required in order to obtain B<BIGNUM>s from the
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| 31 | B<BN_CTX>, in most cases BN_CTX_end() must be called before the B<BN_CTX> may
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| 32 | be freed by BN_CTX_free(). If B<c> is NULL, nothing is done.
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| 33 |
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| 34 | A given B<BN_CTX> must only be used by a single thread of execution. No
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| 35 | locking is performed, and the internal pool allocator will not properly handle
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| 36 | multiple threads of execution.
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| 37 |
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| 38 | =head1 RETURN VALUES
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| 39 |
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| 40 | BN_CTX_new() and BN_CTX_secure_new() return a pointer to the B<BN_CTX>.
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| 41 | If the allocation fails,
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| 42 | they return B<NULL> and sets an error code that can be obtained by
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| 43 | L<ERR_get_error(3)>.
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| 44 |
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| 45 | BN_CTX_free() has no return values.
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| 46 |
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| 47 | =head1 REMOVED FUNCTIONALITY
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| 48 |
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| 49 | void BN_CTX_init(BN_CTX *c);
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| 50 |
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| 51 | BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications should
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| 52 | replace use of BN_CTX_init with BN_CTX_new instead:
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| 53 |
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| 54 | BN_CTX *ctx;
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| 55 | ctx = BN_CTX_new();
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| 56 | if (!ctx)
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| 57 | /* error */
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| 58 | ...
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| 59 | BN_CTX_free(ctx);
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| 60 |
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| 61 | =head1 SEE ALSO
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| 62 |
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| 63 | L<ERR_get_error(3)>, L<BN_add(3)>,
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| 64 | L<BN_CTX_start(3)>
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| 65 |
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| 66 | =head1 HISTORY
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| 67 |
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| 68 | BN_CTX_init() was removed in OpenSSL 1.1.0.
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| 69 |
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| 70 | =head1 COPYRIGHT
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| 71 |
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| 72 | Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
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| 73 |
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| 74 | Licensed under the OpenSSL license (the "License"). You may not use
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| 75 | this file except in compliance with the License. You can obtain a copy
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| 76 | in the file LICENSE in the source distribution or at
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| 77 | L<https://www.openssl.org/source/license.html>.
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| 78 |
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| 79 | =cut
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