mirror of https://github.com/openssl/openssl.git
90 lines
2.7 KiB
Plaintext
90 lines
2.7 KiB
Plaintext
=pod
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=head1 NAME
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BN_CTX_new_ex, BN_CTX_new, BN_CTX_secure_new_ex, BN_CTX_secure_new, BN_CTX_free
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- allocate and free BN_CTX structures
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=head1 SYNOPSIS
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#include <openssl/bn.h>
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BN_CTX *BN_CTX_new_ex(OPENSSL_CTX *ctx);
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BN_CTX *BN_CTX_new(void);
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BN_CTX *BN_CTX_secure_new_ex(OPENSSL_CTX *ctx);
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BN_CTX *BN_CTX_secure_new(void);
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void BN_CTX_free(BN_CTX *c);
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=head1 DESCRIPTION
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A B<BN_CTX> is a structure that holds B<BIGNUM> temporary variables used by
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library functions. Since dynamic memory allocation to create B<BIGNUM>s
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is rather expensive when used in conjunction with repeated subroutine
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calls, the B<BN_CTX> structure is used.
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BN_CTX_new_ex() allocates and initializes a B<BN_CTX> structure for the given
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library context B<ctx>. The <ctx> value may be NULL in which case the default
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library context will be used. BN_CTX_new() is the same as BN_CTX_new_ex() except
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that the default library context is always used.
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BN_CTX_secure_new_ex() allocates and initializes a B<BN_CTX> structure
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but uses the secure heap (see L<CRYPTO_secure_malloc(3)>) to hold the
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B<BIGNUM>s for the given library context B<ctx>. The <ctx> value may be NULL in
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which case the default library context will be used. BN_CTX_secure_new() is the
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same as BN_CTX_secure_new_ex() except that the default library context is always
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used.
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BN_CTX_free() frees the components of the B<BN_CTX> and the structure itself.
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Since BN_CTX_start() is required in order to obtain B<BIGNUM>s from the
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B<BN_CTX>, in most cases BN_CTX_end() must be called before the B<BN_CTX> may
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be freed by BN_CTX_free(). If B<c> is NULL, nothing is done.
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A given B<BN_CTX> must only be used by a single thread of execution. No
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locking is performed, and the internal pool allocator will not properly handle
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multiple threads of execution.
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=head1 RETURN VALUES
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BN_CTX_new() and BN_CTX_secure_new() return a pointer to the B<BN_CTX>.
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If the allocation fails,
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they return B<NULL> and sets an error code that can be obtained by
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L<ERR_get_error(3)>.
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BN_CTX_free() has no return values.
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=head1 REMOVED FUNCTIONALITY
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void BN_CTX_init(BN_CTX *c);
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BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications should
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replace use of BN_CTX_init with BN_CTX_new instead:
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BN_CTX *ctx;
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ctx = BN_CTX_new();
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if (!ctx)
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/* error */
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...
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BN_CTX_free(ctx);
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=head1 SEE ALSO
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L<ERR_get_error(3)>, L<BN_add(3)>,
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L<BN_CTX_start(3)>
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=head1 HISTORY
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BN_CTX_init() was removed in OpenSSL 1.1.0.
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=head1 COPYRIGHT
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Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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