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Title "BN_CTX_NEW 3"
BN_CTX_NEW 3 "2020-04-21" "1.1.1g" "OpenSSL"
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"NAME"
BN_CTX_new, BN_CTX_secure_new, BN_CTX_free - allocate and free BN_CTX structures
"SYNOPSIS"
Header "SYNOPSIS" .Vb 1 #include <openssl/bn.h> \& BN_CTX *BN_CTX_new(void); \& BN_CTX *BN_CTX_secure_new(void); \& void BN_CTX_free(BN_CTX *c); .Ve
"DESCRIPTION"
Header "DESCRIPTION" A \s-1BN_CTX\s0 is a structure that holds \s-1BIGNUM\s0 temporary variables used by library functions. Since dynamic memory allocation to create \s-1BIGNUM\s0s is rather expensive when used in conjunction with repeated subroutine calls, the \s-1BN_CTX\s0 structure is used.

\fBBN_CTX_new() allocates and initializes a \s-1BN_CTX\s0 structure. \fBBN_CTX_secure_new() allocates and initializes a \s-1BN_CTX\s0 structure but uses the secure heap (see CRYPTO_secure_malloc\|(3)) to hold the \fB\s-1BIGNUM\s0s.

\fBBN_CTX_free() frees the components of the \s-1BN_CTX\s0 and the structure itself. Since BN_CTX_start() is required in order to obtain \s-1BIGNUM\s0s from the \fB\s-1BN_CTX\s0, in most cases BN_CTX_end() must be called before the \s-1BN_CTX\s0 may be freed by BN_CTX_free(). If c is \s-1NULL,\s0 nothing is done.

A given \s-1BN_CTX\s0 must only be used by a single thread of execution. No locking is performed, and the internal pool allocator will not properly handle multiple threads of execution.

"RETURN VALUES"
Header "RETURN VALUES" \fBBN_CTX_new() and BN_CTX_secure_new() return a pointer to the \s-1BN_CTX\s0. If the allocation fails, they return \s-1NULL\s0 and sets an error code that can be obtained by \fBERR_get_error\|(3).

\fBBN_CTX_free() has no return values.

"REMOVED FUNCTIONALITY"
Header "REMOVED FUNCTIONALITY" .Vb 1 void BN_CTX_init(BN_CTX *c); .Ve

\fBBN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications should replace use of BN_CTX_init with BN_CTX_new instead:

.Vb 6 BN_CTX *ctx; ctx = BN_CTX_new(); if (!ctx) /* error */ ... BN_CTX_free(ctx); .Ve

"SEE ALSO"
Header "SEE ALSO" \fBERR_get_error\|(3), BN_add\|(3), \fBBN_CTX_start\|(3)
"HISTORY"
Header "HISTORY" \fBBN_CTX_init() was removed in OpenSSL 1.1.0.
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.