NetBSD/lib/libcrypto/man/BN_add.3

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.IX Title "BN_add 3"
.TH BN_add 3 "0.9.6a" "2000-07-22" "OpenSSL"
.UC
.SH "NAME"
BN_add, BN_sub, BN_mul, BN_div, BN_sqr, BN_mod, BN_mod_mul, BN_exp,
BN_mod_exp, BN_gcd \- arithmetic operations on BIGNUMs
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include \*[Lt]openssl/bn.h\*[Gt]
.Ve
.Vb 1
\& int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
.Ve
.Vb 1
\& int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
.Ve
.Vb 1
\& int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
.Ve
.Vb 2
\& int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
\&         BN_CTX *ctx);
.Ve
.Vb 1
\& int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx);
.Ve
.Vb 1
\& int BN_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
.Ve
.Vb 2
\& int BN_mod_mul(BIGNUM *ret, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
\&         BN_CTX *ctx);
.Ve
.Vb 1
\& int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
.Ve
.Vb 2
\& int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
\&         const BIGNUM *m, BN_CTX *ctx);
.Ve
.Vb 1
\& int BN_gcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIBN_add()\fR adds \fBa\fR and \fBb\fR and places the result in \fBr\fR (\f(CW\*(C`r=a+b\*(C'\fR).
\&\fBr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fBa\fR or \fBb\fR.
.PP
\&\fIBN_sub()\fR subtracts \fBb\fR from \fBa\fR and places the result in \fBr\fR (\f(CW\*(C`r=a\-b\*(C'\fR).
.PP
\&\fIBN_mul()\fR multiplies \fBa\fR and \fBb\fR and places the result in \fBr\fR (\f(CW\*(C`r=a*b\*(C'\fR).
\&\fBr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fBa\fR or \fBb\fR.
For multiplication by powers of 2, use BN_lshift(3).
.PP
\&\fIBN_div()\fR divides \fBa\fR by \fBd\fR and places the result in \fBdv\fR and the
remainder in \fBrem\fR (\f(CW\*(C`dv=a/d, rem=a%d\*(C'\fR). Either of \fBdv\fR and \fBrem\fR may
be \s-1NULL\s0, in which case the respective value is not returned.
For division by powers of 2, use \fIBN_rshift\fR\|(3).
.PP
\&\fIBN_sqr()\fR takes the square of \fBa\fR and places the result in \fBr\fR
(\f(CW\*(C`r=a^2\*(C'\fR). \fBr\fR and \fBa\fR may be the same \fB\s-1BIGNUM\s0\fR.
This function is faster than BN_mul(r,a,a).
.PP
\&\fIBN_mod()\fR find the remainder of \fBa\fR divided by \fBm\fR and places it in
\&\fBrem\fR (\f(CW\*(C`rem=a%m\*(C'\fR).
.PP
\&\fIBN_mod_mul()\fR multiplies \fBa\fR by \fBb\fR and finds the remainder when
divided by \fBm\fR (\f(CW\*(C`r=(a*b)%m\*(C'\fR). \fBr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fBa\fR
or \fBb\fR. For a more efficient algorithm, see
BN_mod_mul_montgomery(3); for repeated
computations using the same modulus, see BN_mod_mul_reciprocal(3).
.PP
\&\fIBN_exp()\fR raises \fBa\fR to the \fBp\fR\-th power and places the result in \fBr\fR
(\f(CW\*(C`r=a^p\*(C'\fR). This function is faster than repeated applications of
\&\fIBN_mul()\fR.
.PP
\&\fIBN_mod_exp()\fR computes \fBa\fR to the \fBp\fR\-th power modulo \fBm\fR (\f(CW\*(C`r=a^p %
m\*(C'\fR). This function uses less time and space than \fIBN_exp()\fR.
.PP
\&\fIBN_gcd()\fR computes the greatest common divisor of \fBa\fR and \fBb\fR and
places the result in \fBr\fR. \fBr\fR may be the same \fB\s-1BIGNUM\s0\fR as \fBa\fR or
\&\fBb\fR.
.PP
For all functions, \fBctx\fR is a previously allocated \fB\s-1BN_CTX\s0\fR used for
temporary variables; see BN_CTX_new(3).
.PP
Unless noted otherwise, the result \fB\s-1BIGNUM\s0\fR must be different from
the arguments.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
For all functions, 1 is returned for success, 0 on error. The return
value should always be checked (e.g., \f(CW\*(C`if (!BN_add(r,a,b)) goto err;\*(C'\fR).
The error codes can be obtained by ERR_get_error(3).
.SH "SEE ALSO"
.IX Header "SEE ALSO"
openssl_bn(3), openssl_err(3), BN_CTX_new(3),
BN_add_word(3), BN_set_bit(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fIBN_add()\fR, \fIBN_sub()\fR, \fIBN_div()\fR, \fIBN_sqr()\fR, \fIBN_mod()\fR, \fIBN_mod_mul()\fR,
\&\fIBN_mod_exp()\fR and \fIBN_gcd()\fR are available in all versions of SSLeay and
OpenSSL. The \fBctx\fR argument to \fIBN_mul()\fR was added in SSLeay
0.9.1b. \fIBN_exp()\fR appeared in SSLeay 0.9.0.