NAME
BN_set_bit
,
BN_clear_bit
, BN_is_bit_set
,
BN_mask_bits
, BN_lshift
,
BN_lshift1
, BN_rshift
,
BN_rshift1
—
bit operations on BIGNUMs
SYNOPSIS
#include
<openssl/bn.h>
int
BN_set_bit
(BIGNUM *a,
int n);
int
BN_clear_bit
(BIGNUM *a,
int n);
int
BN_is_bit_set
(const BIGNUM *a,
int n);
int
BN_mask_bits
(BIGNUM *a,
int n);
int
BN_lshift
(BIGNUM *r,
const BIGNUM *a, int n);
int
BN_lshift1
(BIGNUM *r,
BIGNUM *a);
int
BN_rshift
(BIGNUM *r,
BIGNUM *a, int n);
int
BN_rshift1
(BIGNUM *r,
BIGNUM *a);
DESCRIPTION
BN_set_bit
()
sets bit n in a to 1
(a|=(1<<n)
). The number is expanded if
necessary.
BN_clear_bit
()
sets bit n in a to 0
(a&=~(1<<n)
). An error occurs if
a is shorter than n bits.
BN_is_bit_set
()
tests if bit n in a is set.
BN_mask_bits
()
truncates a to an n bit number
(a&=~((~0)>>n)
). An error occurs if
a already is shorter than n
bits.
BN_lshift
()
shifts a left by n bits and
places the result in r
(r=a*2^n
). Note that n must be
non-negative.
BN_lshift1
()
shifts a left by one and places the result in
r (r=2*a
).
BN_rshift
()
shifts a right by n bits and
places the result in r
(r=a/2^n
). Note that n must be
non-negative.
BN_rshift1
()
shifts a right by one and places the result in
r (r=a/2
).
For the shift functions, r and a may be the same variable.
RETURN VALUES
BN_is_bit_set
() returns 1 if the bit is
set, 0 otherwise.
All other functions return 1 for success, 0 on error. The error codes can be obtained by ERR_get_error(3).
SEE ALSO
BN_add(3), BN_new(3), BN_num_bytes(3), BN_set_negative(3), BN_zero(3)
HISTORY
BN_set_bit
(),
BN_clear_bit
(),
BN_is_bit_set
(),
BN_mask_bits
(), BN_lshift
(),
BN_lshift1
(), BN_rshift
(),
and BN_rshift1
() are available in all versions of
SSLeay and OpenSSL.