1BN_CTX_NEW(3ossl)                   OpenSSL                  BN_CTX_NEW(3ossl)
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NAME

6       BN_CTX_new_ex, BN_CTX_new, BN_CTX_secure_new_ex, BN_CTX_secure_new,
7       BN_CTX_free - allocate and free BN_CTX structures
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SYNOPSIS

10        #include <openssl/bn.h>
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12        BN_CTX *BN_CTX_new_ex(OSSL_LIB_CTX *ctx);
13        BN_CTX *BN_CTX_new(void);
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15        BN_CTX *BN_CTX_secure_new_ex(OSSL_LIB_CTX *ctx);
16        BN_CTX *BN_CTX_secure_new(void);
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18        void BN_CTX_free(BN_CTX *c);
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DESCRIPTION

21       A BN_CTX is a structure that holds BIGNUM temporary variables used by
22       library functions. Since dynamic memory allocation to create BIGNUMs is
23       rather expensive when used in conjunction with repeated subroutine
24       calls, the BN_CTX structure is used.
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26       BN_CTX_new_ex() allocates and initializes a BN_CTX structure for the
27       given library context ctx. The <ctx> value may be NULL in which case
28       the default library context will be used. BN_CTX_new() is the same as
29       BN_CTX_new_ex() except that the default library context is always used.
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31       BN_CTX_secure_new_ex() allocates and initializes a BN_CTX structure but
32       uses the secure heap (see CRYPTO_secure_malloc(3)) to hold the BIGNUMs
33       for the given library context ctx. The <ctx> value may be NULL in which
34       case the default library context will be used. BN_CTX_secure_new() is
35       the same as BN_CTX_secure_new_ex() except that the default library
36       context is always used.
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38       BN_CTX_free() frees the components of the BN_CTX and the structure
39       itself.  Since BN_CTX_start() is required in order to obtain BIGNUMs
40       from the BN_CTX, in most cases BN_CTX_end() must be called before the
41       BN_CTX may be freed by BN_CTX_free().  If c is NULL, nothing is done.
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43       A given BN_CTX must only be used by a single thread of execution.  No
44       locking is performed, and the internal pool allocator will not properly
45       handle multiple threads of execution.
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RETURN VALUES

48       BN_CTX_new() and BN_CTX_secure_new() return a pointer to the BN_CTX.
49       If the allocation fails, they return NULL and sets an error code that
50       can be obtained by ERR_get_error(3).
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52       BN_CTX_free() has no return values.
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REMOVED FUNCTIONALITY

55        void BN_CTX_init(BN_CTX *c);
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57       BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications
58       should replace use of BN_CTX_init with BN_CTX_new instead:
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60        BN_CTX *ctx;
61        ctx = BN_CTX_new();
62        if (!ctx)
63            /* error */
64        ...
65        BN_CTX_free(ctx);
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SEE ALSO

68       ERR_get_error(3), BN_add(3), BN_CTX_start(3)
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HISTORY

71       BN_CTX_init() was removed in OpenSSL 1.1.0.
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74       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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76       Licensed under the Apache License 2.0 (the "License").  You may not use
77       this file except in compliance with the License.  You can obtain a copy
78       in the file LICENSE in the source distribution or at
79       <https://www.openssl.org/source/license.html>.
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833.0.5                             2022-11-01                 BN_CTX_NEW(3ossl)
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