NAME    [Toc]    [Back]

       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    [Toc]    [Back]

       libcrypto, -lcrypto

SYNOPSIS    [Toc]    [Back]

        #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    [Toc]    [Back]

       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'). 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'). 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    [Toc]    [Back]

       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    [Toc]    [Back]

       openssl_bn(3), BN_num_bytes(3), BN_add(3)

HISTORY    [Toc]    [Back]

       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.