1=pod 2 3=head1 NAME 4 5BN_CTX_new_ex, BN_CTX_new, BN_CTX_secure_new_ex, BN_CTX_secure_new, BN_CTX_free 6- allocate and free BN_CTX structures 7 8=head1 SYNOPSIS 9 10 #include <openssl/bn.h> 11 12 BN_CTX *BN_CTX_new_ex(OSSL_LIB_CTX *ctx); 13 BN_CTX *BN_CTX_new(void); 14 15 BN_CTX *BN_CTX_secure_new_ex(OSSL_LIB_CTX *ctx); 16 BN_CTX *BN_CTX_secure_new(void); 17 18 void BN_CTX_free(BN_CTX *c); 19 20=head1 DESCRIPTION 21 22A B<BN_CTX> is a structure that holds B<BIGNUM> temporary variables used by 23library functions. Since dynamic memory allocation to create B<BIGNUM>s 24is rather expensive when used in conjunction with repeated subroutine 25calls, the B<BN_CTX> structure is used. 26 27BN_CTX_new_ex() allocates and initializes a B<BN_CTX> structure for the given 28library context B<ctx>. The <ctx> value may be NULL in which case the default 29library context will be used. BN_CTX_new() is the same as BN_CTX_new_ex() except 30that the default library context is always used. 31 32BN_CTX_secure_new_ex() allocates and initializes a B<BN_CTX> structure 33but uses the secure heap (see L<CRYPTO_secure_malloc(3)>) to hold the 34B<BIGNUM>s for the given library context B<ctx>. The <ctx> value may be NULL in 35which case the default library context will be used. BN_CTX_secure_new() is the 36same as BN_CTX_secure_new_ex() except that the default library context is always 37used. 38 39BN_CTX_free() frees the components of the B<BN_CTX> and the structure itself. 40Since BN_CTX_start() is required in order to obtain B<BIGNUM>s from the 41B<BN_CTX>, in most cases BN_CTX_end() must be called before the B<BN_CTX> may 42be freed by BN_CTX_free(). If B<c> is NULL, nothing is done. 43 44A given B<BN_CTX> must only be used by a single thread of execution. No 45locking is performed, and the internal pool allocator will not properly handle 46multiple threads of execution. 47 48=head1 RETURN VALUES 49 50BN_CTX_new() and BN_CTX_secure_new() return a pointer to the B<BN_CTX>. 51If the allocation fails, 52they return B<NULL> and sets an error code that can be obtained by 53L<ERR_get_error(3)>. 54 55BN_CTX_free() has no return values. 56 57=head1 REMOVED FUNCTIONALITY 58 59 void BN_CTX_init(BN_CTX *c); 60 61BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications should 62replace use of BN_CTX_init with BN_CTX_new instead: 63 64 BN_CTX *ctx; 65 ctx = BN_CTX_new(); 66 if (!ctx) 67 /* error */ 68 ... 69 BN_CTX_free(ctx); 70 71=head1 SEE ALSO 72 73L<ERR_get_error(3)>, L<BN_add(3)>, 74L<BN_CTX_start(3)> 75 76=head1 HISTORY 77 78BN_CTX_init() was removed in OpenSSL 1.1.0. 79 80=head1 COPYRIGHT 81 82Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. 83 84Licensed under the Apache License 2.0 (the "License"). You may not use 85this file except in compliance with the License. You can obtain a copy 86in the file LICENSE in the source distribution or at 87L<https://www.openssl.org/source/license.html>. 88 89=cut 90
