1BN_CTX_START(3ossl)                 OpenSSL                BN_CTX_START(3ossl)
2
3
4

NAME

6       BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables
7

SYNOPSIS

9        #include <openssl/bn.h>
10
11        void BN_CTX_start(BN_CTX *ctx);
12
13        BIGNUM *BN_CTX_get(BN_CTX *ctx);
14
15        void BN_CTX_end(BN_CTX *ctx);
16

DESCRIPTION

18       These functions are used to obtain temporary BIGNUM variables from a
19       BN_CTX (which can been created by using BN_CTX_new(3)) in order to save
20       the overhead of repeatedly creating and freeing BIGNUMs in functions
21       that are called from inside a loop.
22
23       A function must call BN_CTX_start() first. Then, BN_CTX_get() may be
24       called repeatedly to obtain temporary BIGNUMs. All BN_CTX_get() calls
25       must be made before calling any other functions that use the ctx as an
26       argument.
27
28       Finally, BN_CTX_end() must be called before returning from the
29       function.  If ctx is NULL, nothing is done.  When BN_CTX_end() is
30       called, the BIGNUM pointers obtained from BN_CTX_get() become invalid.
31

RETURN VALUES

33       BN_CTX_start() and BN_CTX_end() return no values.
34
35       BN_CTX_get() returns a pointer to the BIGNUM, or NULL on error.  Once
36       BN_CTX_get() has failed, the subsequent calls will return NULL as well,
37       so it is sufficient to check the return value of the last BN_CTX_get()
38       call. In case of an error, an error code is set, which can be obtained
39       by ERR_get_error(3).
40

SEE ALSO

42       BN_CTX_new(3)
43
45       Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
46
47       Licensed under the Apache License 2.0 (the "License").  You may not use
48       this file except in compliance with the License.  You can obtain a copy
49       in the file LICENSE in the source distribution or at
50       <https://www.openssl.org/source/license.html>.
51
52
53
543.0.9                             2023-07-27               BN_CTX_START(3ossl)
Impressum