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);
=head1 DESCRIPTION
BN_add() adds I and I** and places the result in I (C).
I may be the same B as I**** or I****.
BN_sub() subtracts I**** from I**** and places the result in I (C).
BN_mul() multiplies I and I**** and places the result in I (C).
I may be the same B as I**** or I****.
For multiplication by powers of 2, use L.
BN_sqr() takes the square of I**** and places the result in I
(C). I and I may be the same B.
This function is faster than BN_mul(r,a,a).
BN_div() divides I by I and places the result in I and the
remainder in I (C). Either of I and I may
be B, in which case the respective value is not returned.
The result is rounded towards zero; thus if I 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 I set to B.
BN_nnmod() reduces I modulo I and places the non-negative
remainder in I.
BN_mod_add() adds I to I**** modulo I and places the non-negative
result in I.
BN_mod_sub() subtracts I**** from I**** modulo I and places the
non-negative result in I.
BN_mod_mul() multiplies I by I**** and finds the non-negative
remainder respective to modulus I (C). I may be
the same B as I**** or I****. For more efficient algorithms for
repeated computations using the same modulus, see
L and
L.
BN_mod_sqr() takes the square of I**** modulo B and places the
result in I.
BN_exp() raises I to the I**-th power and places the result in I
(C). This function is faster than repeated applications of
BN_mul().
BN_mod_exp() computes I to the I

-th power modulo I (C). This function uses less time and space than BN_exp(). Do not call this
function when B is even and any of the parameters have the
B flag set.
BN_gcd() computes the greatest common divisor of I and I** and
places the result in I. I may be the same B as I**** or
I****.
For all functions, I is a previously allocated B used for
temporary variables; see L.
Unless noted otherwise, the result B must be different from
the arguments.
=head1 RETURN VALUES
For all functions, 1 is returned for success, 0 on error. The return
value should always be checked (e.g., C).
The error codes can be obtained by L.
=head1 SEE ALSO
L, L, L,
L, L
=head1 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 I 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.
=cut
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