Updated: 2021/Apr/14


BN_set_bit(3)                       OpenSSL                      BN_set_bit(3)



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

LIBRARY
       libcrypto, -lcrypto

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 nonnegative. 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 nonnegative. 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_num_bytes(3), BN_add(3)

COPYRIGHT
       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.



1.1.1i                            2020-12-10                     BN_set_bit(3)