1=pod 2 3=head1 NAME 4 5BN_CTX_new, BN_CTX_secure_new, BN_CTX_free - allocate and free BN_CTX structures 6 7=head1 SYNOPSIS 8 9 #include <openssl/bn.h> 10 11 BN_CTX *BN_CTX_new(void); 12 13 BN_CTX *BN_CTX_secure_new(void); 14 15 void BN_CTX_free(BN_CTX *c); 16 17=head1 DESCRIPTION 18 19A B<BN_CTX> is a structure that holds B<BIGNUM> temporary variables used by 20library functions. Since dynamic memory allocation to create B<BIGNUM>s 21is rather expensive when used in conjunction with repeated subroutine 22calls, the B<BN_CTX> structure is used. 23 24BN_CTX_new() allocates and initializes a B<BN_CTX> structure. 25BN_CTX_secure_new() allocates and initializes a B<BN_CTX> structure 26but uses the secure heap (see L<CRYPTO_secure_malloc(3)>) to hold the 27B<BIGNUM>s. 28 29BN_CTX_free() frees the components of the B<BN_CTX> and the structure itself. 30Since BN_CTX_start() is required in order to obtain B<BIGNUM>s from the 31B<BN_CTX>, in most cases BN_CTX_end() must be called before the B<BN_CTX> may 32be freed by BN_CTX_free(). If B<c> is NULL, nothing is done. 33 34A given B<BN_CTX> must only be used by a single thread of execution. No 35locking is performed, and the internal pool allocator will not properly handle 36multiple threads of execution. 37 38=head1 RETURN VALUES 39 40BN_CTX_new() and BN_CTX_secure_new() return a pointer to the B<BN_CTX>. 41If the allocation fails, 42they return B<NULL> and sets an error code that can be obtained by 43L<ERR_get_error(3)>. 44 45BN_CTX_free() has no return values. 46 47=head1 REMOVED FUNCTIONALITY 48 49 void BN_CTX_init(BN_CTX *c); 50 51BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications should 52replace use of BN_CTX_init with BN_CTX_new instead: 53 54 BN_CTX *ctx; 55 ctx = BN_CTX_new(); 56 if (!ctx) 57 /* error */ 58 ... 59 BN_CTX_free(ctx); 60 61=head1 SEE ALSO 62 63L<ERR_get_error(3)>, L<BN_add(3)>, 64L<BN_CTX_start(3)> 65 66=head1 HISTORY 67 68BN_CTX_init() was removed in OpenSSL 1.1.0. 69 70=head1 COPYRIGHT 71 72Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. 73 74Licensed under the OpenSSL license (the "License"). You may not use 75this file except in compliance with the License. You can obtain a copy 76in the file LICENSE in the source distribution or at 77L<https://www.openssl.org/source/license.html>. 78 79=cut 80