NetBSD/lib/libcrypto/man/BN_CTX_new.3

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.\" $NetBSD: BN_CTX_new.3,v 1.12 2003/07/24 14:16:37 itojun Exp $
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.IX Title "BN_CTX_new 3"
.TH BN_CTX_new 3 "0.9.7b" "2002-09-25" "OpenSSL"
.UC
.SH "NAME"
BN_CTX_new, BN_CTX_init, BN_CTX_free \- allocate and free \s-1BN_CTX\s0 structures
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/bn.h>
.Ve
.Vb 1
\& BN_CTX *BN_CTX_new(void);
.Ve
.Vb 1
\& void BN_CTX_init(BN_CTX *c);
.Ve
.Vb 1
\& void BN_CTX_free(BN_CTX *c);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
A \fB\s-1BN_CTX\s0\fR is a structure that holds \fB\s-1BIGNUM\s0\fR temporary variables used by
library functions. Since dynamic memory allocation to create \fB\s-1BIGNUM\s0\fRs
is rather expensive when used in conjunction with repeated subroutine
calls, the \fB\s-1BN_CTX\s0\fR structure is used.
.PP
\&\fIBN_CTX_new()\fR allocates and initializes a \fB\s-1BN_CTX\s0\fR
structure. \fIBN_CTX_init()\fR initializes an existing uninitialized
\&\fB\s-1BN_CTX\s0\fR.
.PP
\&\fIBN_CTX_free()\fR frees the components of the \fB\s-1BN_CTX\s0\fR, and if it was
created by \fIBN_CTX_new()\fR, also the structure itself.
If BN_CTX_start(3) has been used on the \fB\s-1BN_CTX\s0\fR,
BN_CTX_end(3) must be called before the \fB\s-1BN_CTX\s0\fR
may be freed by \fIBN_CTX_free()\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIBN_CTX_new()\fR returns a pointer to the \fB\s-1BN_CTX\s0\fR. If the allocation fails,
it returns \fB\s-1NULL\s0\fR and sets an error code that can be obtained by
ERR_get_error(3).
.PP
\&\fIBN_CTX_init()\fR and \fIBN_CTX_free()\fR have no return values.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
openssl_bn(3), ERR_get_error(3), BN_add(3),
BN_CTX_start(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fIBN_CTX_new()\fR and \fIBN_CTX_free()\fR are available in all versions on SSLeay
and OpenSSL. \fIBN_CTX_init()\fR was added in SSLeay 0.9.1b.