You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
52 lines
1.4 KiB
52 lines
1.4 KiB
=pod |
|
|
|
=head1 NAME |
|
|
|
BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables |
|
|
|
=head1 SYNOPSIS |
|
|
|
#include <openssl/bn.h> |
|
|
|
void BN_CTX_start(BN_CTX *ctx); |
|
|
|
BIGNUM *BN_CTX_get(BN_CTX *ctx); |
|
|
|
void BN_CTX_end(BN_CTX *ctx); |
|
|
|
=head1 DESCRIPTION |
|
|
|
These functions are used to obtain temporary B<BIGNUM> variables from |
|
a B<BN_CTX> (which can been created by using L<BN_CTX_new(3)|BN_CTX_new(3)>) |
|
in order to save the overhead of repeatedly creating and |
|
freeing B<BIGNUM>s in functions that are called from inside a loop. |
|
|
|
A function must call BN_CTX_start() first. Then, BN_CTX_get() may be |
|
called repeatedly to obtain temporary B<BIGNUM>s. All BN_CTX_get() |
|
calls must be made before calling any other functions that use the |
|
B<ctx> as an argument. |
|
|
|
Finally, BN_CTX_end() must be called before returning from the function. |
|
When BN_CTX_end() is called, the B<BIGNUM> pointers obtained from |
|
BN_CTX_get() become invalid. |
|
|
|
=head1 RETURN VALUES |
|
|
|
BN_CTX_start() and BN_CTX_end() return no values. |
|
|
|
BN_CTX_get() returns a pointer to the B<BIGNUM>, or B<NULL> on error. |
|
Once BN_CTX_get() has failed, the subsequent calls will return B<NULL> |
|
as well, so it is sufficient to check the return value of the last |
|
BN_CTX_get() call. In case of an error, an error code is set, which |
|
can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. |
|
|
|
|
|
=head1 SEE ALSO |
|
|
|
L<BN_CTX_new(3)|BN_CTX_new(3)> |
|
|
|
=head1 HISTORY |
|
|
|
BN_CTX_start(), BN_CTX_get() and BN_CTX_end() were added in OpenSSL 0.9.5. |
|
|
|
=cut
|
|
|