1BN_CTX_NEW(3)                       OpenSSL                      BN_CTX_NEW(3)
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NAME

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

10        #include <openssl/bn.h>
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12        BN_CTX *BN_CTX_new(void);
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14        BN_CTX *BN_CTX_secure_new(void);
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16        void BN_CTX_free(BN_CTX *c);
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DESCRIPTION

19       A BN_CTX is a structure that holds BIGNUM temporary variables used by
20       library functions. Since dynamic memory allocation to create BIGNUMs is
21       rather expensive when used in conjunction with repeated subroutine
22       calls, the BN_CTX structure is used.
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24       BN_CTX_new() allocates and initializes a BN_CTX structure.
25       BN_CTX_secure_new() allocates and initializes a BN_CTX structure but
26       uses the secure heap (see CRYPTO_secure_malloc(3)) to hold the BIGNUMs.
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28       BN_CTX_free() frees the components of the BN_CTX and the structure
29       itself.  Since BN_CTX_start() is required in order to obtain BIGNUMs
30       from the BN_CTX, in most cases BN_CTX_end() must be called before the
31       BN_CTX may be freed by BN_CTX_free().  If c is NULL, nothing is done.
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33       A given BN_CTX must only be used by a single thread of execution.  No
34       locking is performed, and the internal pool allocator will not properly
35       handle multiple threads of execution.
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RETURN VALUES

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

45        void BN_CTX_init(BN_CTX *c);
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47       BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications
48       should replace use of BN_CTX_init with BN_CTX_new instead:
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50        BN_CTX *ctx;
51        ctx = BN_CTX_new();
52        if (!ctx)
53            /* error */
54        ...
55        BN_CTX_free(ctx);
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SEE ALSO

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

61       BN_CTX_init() was removed in OpenSSL 1.1.0.
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64       Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
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66       Licensed under the OpenSSL license (the "License").  You may not use
67       this file except in compliance with the License.  You can obtain a copy
68       in the file LICENSE in the source distribution or at
69       <https://www.openssl.org/source/license.html>.
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731.1.1l                            2021-09-15                     BN_CTX_NEW(3)
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