BNadd(3) OpenSSL BNadd(3)

NAME
       BNadd, BNsub, BNmul, BNsqr, BNdiv, BNmod, BNnnmod, BNmodadd,
       BNmodsub, BNmodmul, BNmodsqr, BNexp, BNmodexp, BNgcd -
       arithmetic operations on BIGNUMs

SYNOPSIS
        #include 

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

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

        int BNmul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BNCTX *ctx);

        int BNsqr(BIGNUM *r, BIGNUM *a, BNCTX *ctx);

        int BNdiv(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
                BNCTX *ctx);

        int BNmod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BNCTX *ctx);

        int BNnnmod(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BNCTX *ctx);

        int BNmodadd(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
                BNCTX *ctx);

        int BNmodsub(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
                BNCTX *ctx);

        int BNmodmul(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
                BNCTX *ctx);

        int BNmodsqr(BIGNUM *r, BIGNUM *a, const BIGNUM *m, BNCTX *ctx);

        int BNexp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BNCTX *ctx);

        int BNmodexp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
                const BIGNUM *m, BNCTX *ctx);

        int BNgcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BNCTX *ctx);

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

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

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

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

       BNdiv() 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 NNUULLLL, 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 BNrshift(3).

       BNmod() corresponds to BNdiv() with dv set to NNUULLLL.

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

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

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

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

       BNmodsqr() takes the square of a modulo mm and places the result in r.

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

       BNmodexp() computes a to the p-th power modulo m ("r=a^p % m"). This
       function uses less time and space than BNexp().

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

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

       Unless noted otherwise, the result BBIIGGNNUUMM 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 (!BNadd(r,a,b)) goto err;").
       The error codes can be obtained by ERRgeterror(3).

SEE ALSO
       bn(3), ERRgeterror(3), BNCTXnew(3), BNaddword(3), BNsetbit(3)

HISTORY       BNadd(), BNsub(), BNsqr(), BNdiv(), BNmod(), BNmodmul(),
       BNmodexp() and BNgcd() are available in all versions of SSLeay and
       OpenSSL. The ctx argument to BNmul() was added in SSLeay 0.9.1b.
       BNexp() appeared in SSLeay 0.9.0.  BNnnmod(), BNmodadd(),
       BNmodsub(), and BNmodsqr() were added in OpenSSL 0.9.7.



0.9.7l                            2002-09-25                         BNadd(3)