/usr/man/cat.3/BN_sub.3(/usr/man/cat.3/BN_sub.3)

BN_add(3)                    OpenSSL                    BN_add(3)

NAME

     BN_add, BN_sub, BN_mul, BN_sqr, BN_div, BN_mod, BN_nnmod,
     BN_mod_add, BN_mod_sub, BN_mod_mul, BN_mod_sqr, BN_exp,
     BN_mod_exp, BN_gcd - arithmetic operations on BIGNUMs

SYNOPSIS

      #include <openssl/bn.h>

      int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);

      int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);

      int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);

      int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx);

      int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
              BN_CTX *ctx);

      int BN_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);

      int BN_nnmod(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);

      int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
              BN_CTX *ctx);

      int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
              BN_CTX *ctx);

      int BN_mod_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
              BN_CTX *ctx);

      int BN_mod_sqr(BIGNUM *r, BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);

      int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);

      int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
              const BIGNUM *m, BN_CTX *ctx);

      int BN_gcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);

DESCRIPTION

     BN_add() adds a and b and places the result in r ("r=a+b").
     r may be the same BIGNUM as a or b.

     BN_sub() subtracts b from a and places the result in r
     ("r=a-b").

     BN_mul() multiplies a and b and places the result in r
     ("r=a*b").  r may be the same BIGNUM as a or b.  For
     multiplication by powers of 2, use BN_lshift(3).

1.0.2t               Last change: 2019-09-10                    1

BN_add(3)                    OpenSSL                    BN_add(3)

     BN_sqr() takes the square of a and places the result in r
     ("r=a^2"). r and a may be the same BIGNUM.  This function is
     faster than BN_mul(r,a,a).

     BN_div() divides a by d and places the result in dv and the
     remainder in rem ("dv=a/d, rem=a%d"). Either of dv and rem
     may be NULL, in which case the respective value is not
     returned.  The result is rounded towards zero; thus if a is
     negative, the remainder will be zero or negative.  For
     division by powers of 2, use BN_rshift(3).

     BN_mod() corresponds to BN_div() with dv set to NULL.

     BN_nnmod() reduces a modulo m and places the non-negative
     remainder in r.

     BN_mod_add() adds a to b modulo m and places the non-
     negative result in r.

     BN_mod_sub() subtracts b from a modulo m and places the
     non-negative result in r.

     BN_mod_mul() multiplies a by b and finds the non-negative
     remainder respective to modulus m ("r=(a*b) mod m"). r may
     be the same BIGNUM as a or b. For more efficient algorithms
     for repeated computations using the same modulus, see
     BN_mod_mul_montgomery(3) and BN_mod_mul_reciprocal(3).

     BN_mod_sqr() takes the square of a modulo m and places the
     result in r.

     BN_exp() raises a to the p-th power and places the result in
     r ("r=a^p"). This function is faster than repeated
     applications of BN_mul().

     BN_mod_exp() computes a to the p-th power modulo m ("r=a^p %
     m"). This function uses less time and space than BN_exp().
     Do not call this function when m is even and any of the
     parameters have the BN_FLG_CONSTTIME flag set.

     BN_gcd() computes the greatest common divisor of a and b and
     places the result in r. r may be the same BIGNUM as a or b.

     For all functions, ctx is a previously allocated BN_CTX used
     for temporary variables; see BN_CTX_new(3).

     Unless noted otherwise, the result BIGNUM must be different
     from the arguments.

RETURN VALUES

     For all functions, 1 is returned for success, 0 on error.
     The return value should always be checked (e.g., "if

1.0.2t               Last change: 2019-09-10                    2

BN_add(3)                    OpenSSL                    BN_add(3)

     (!BN_add(r,a,b)) goto err;").  The error codes can be
     obtained by ERR_get_error(3).

SEE ALSO

     bn(3), ERR_get_error(3), BN_CTX_new(3), BN_add_word(3),
     BN_set_bit(3)

HISTORY

     BN_add(), BN_sub(), BN_sqr(), BN_div(), BN_mod(),
     BN_mod_mul(), BN_mod_exp() and BN_gcd() are available in all
     versions of SSLeay and OpenSSL. The ctx argument to BN_mul()
     was added in SSLeay 0.9.1b. BN_exp() appeared in SSLeay
     0.9.0.  BN_nnmod(), BN_mod_add(), BN_mod_sub(), and
     BN_mod_sqr() were added in OpenSSL 0.9.7.

1.0.2t               Last change: 2019-09-10                    3

See also BN_add(3)
See also BN_div(3)
See also BN_exp(3)
See also BN_gcd(3)
See also BN_mod(3)
See also BN_mod_add(3)
See also BN_mod_exp(3)
See also BN_mod_mul(3)
See also BN_mod_sqr(3)
See also BN_mod_sub(3)
See also BN_mul(3)
See also BN_nnmod(3)
See also BN_sqr(3)