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137 .IX Title "BN_CTX_new 3"
138 .TH BN_CTX_new 3 "2009-07-19" "1.0.1n" "OpenSSL"
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144 BN_CTX_new, BN_CTX_init, BN_CTX_free \- allocate and free BN_CTX structures
148 .IX Header "SYNOPSIS"
150 \& #include <openssl/bn.h>
152 \& BN_CTX *BN_CTX_new(void);
154 \& void BN_CTX_init(BN_CTX *c);
156 \& void BN_CTX_free(BN_CTX *c);
159 .IX Header "DESCRIPTION"
160 A \fB\s-1BN_CTX\s0\fR is a structure that holds \fB\s-1BIGNUM\s0\fR temporary variables used by
161 library functions. Since dynamic memory allocation to create \fB\s-1BIGNUM\s0\fRs
162 is rather expensive when used in conjunction with repeated subroutine
163 calls, the \fB\s-1BN_CTX\s0\fR structure is used.
165 \&\fIBN_CTX_new()\fR allocates and initializes a \fB\s-1BN_CTX\s0\fR
166 structure. \fIBN_CTX_init()\fR initializes an existing uninitialized
167 \&\fB\s-1BN_CTX\s0\fR.
169 \&\fIBN_CTX_free()\fR frees the components of the \fB\s-1BN_CTX\s0\fR, and if it was
170 created by \fIBN_CTX_new()\fR, also the structure itself.
171 If \fIBN_CTX_start\fR\|(3) has been used on the \fB\s-1BN_CTX\s0\fR,
172 \&\fIBN_CTX_end\fR\|(3) must be called before the \fB\s-1BN_CTX\s0\fR
173 may be freed by \fIBN_CTX_free()\fR.
175 .IX Header "RETURN VALUES"
176 \&\fIBN_CTX_new()\fR returns a pointer to the \fB\s-1BN_CTX\s0\fR. If the allocation fails,
177 it returns \fB\s-1NULL\s0\fR and sets an error code that can be obtained by
178 \&\fIERR_get_error\fR\|(3).
180 \&\fIBN_CTX_init()\fR and \fIBN_CTX_free()\fR have no return values.
182 .IX Header "SEE ALSO"
183 \&\fIopenssl_bn\fR\|(3), \fIERR_get_error\fR\|(3), \fIBN_add\fR\|(3),
184 \&\fIBN_CTX_start\fR\|(3)
187 \&\fIBN_CTX_new()\fR and \fIBN_CTX_free()\fR are available in all versions on SSLeay
188 and OpenSSL. \fIBN_CTX_init()\fR was added in SSLeay 0.9.1b.