Updated: 2022/Sep/29

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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 Apache License 2.0 (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>.



3.0.12                            2023-05-07                     BN_set_bit(3)