NAME
BN_copy, BN_dup,
BN_with_flags —
copy BIGNUMs
SYNOPSIS
#include
<openssl/bn.h>
BIGNUM *
BN_copy(BIGNUM *to,
const BIGNUM *from);
BIGNUM *
BN_dup(const BIGNUM *from);
void
BN_with_flags(BIGNUM *dest,
const BIGNUM *b, int flags);
DESCRIPTION
BN_copy()
copies from to to.
BN_dup()
creates a new BIGNUM containing the value
from.
BN_with_flags()
creates a
temporary
shallow copy of b in dest. It
places significant restrictions on the copied data. Applications that do not
adhere to these restrictions may encounter unexpected side effects or
crashes. For that reason, use of this function is discouraged.
Any flags provided in flags will be set in
dest in addition to any flags already set in
b. For example, this can be used to create a temporary
copy of a BIGNUM with the
BN_FLG_CONSTTIME flag set for constant time
operations.
The temporary copy in dest will share some internal state with b. For this reason, the following restrictions apply to the use of dest:
- dest should be a newly allocated BIGNUM obtained via a call to BN_new(3). It should not have been used for other purposes or initialised in any way.
- dest must only be used in "read-only" operations, i.e. typically those functions where the relevant parameter is declared "const".
- dest must be used and freed before any further subsequent use of b.
RETURN VALUES
BN_copy() returns to
on success or NULL on error.
BN_dup() returns the new
BIGNUM or NULL on error. The
error codes can be obtained by
ERR_get_error(3).
SEE ALSO
HISTORY
BN_copy() and
BN_dup() first appeared in SSLeay 0.5.1 and have
been available since OpenBSD 2.4.
BN_with_flags() first appeared in OpenSSL
0.9.7h and 0.9.8a and has been available since OpenBSD
4.0.