d836e3679a
manual when the specific function is refered to in the current manual text. This correction was originally introduced in OpenBSD's tracking of OpenSSL.
99 lines
3.4 KiB
Text
99 lines
3.4 KiB
Text
=pod
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=head1 NAME
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BN_add, BN_sub, BN_mul, BN_div, BN_sqr, BN_mod, BN_mod_mul, BN_exp,
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BN_mod_exp, BN_gcd - arithmetic operations on BIGNUMs
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=head1 SYNOPSIS
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#include <openssl/bn.h>
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int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
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int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
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int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
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int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *a, const BIGNUM *d,
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BN_CTX *ctx);
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int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx);
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int BN_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
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int BN_mod_mul(BIGNUM *ret, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
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BN_CTX *ctx);
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int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
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int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
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const BIGNUM *m, BN_CTX *ctx);
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int BN_gcd(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
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=head1 DESCRIPTION
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BN_add() adds B<a> and B<b> and places the result in B<r> (C<r=a+b>).
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B<r> may be the same B<BIGNUM> as B<a> or B<b>.
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BN_sub() subtracts B<b> from B<a> and places the result in B<r> (C<r=a-b>).
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BN_mul() multiplies B<a> and B<b> and places the result in B<r> (C<r=a*b>).
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B<r> may be the same B<BIGNUM> as B<a> or B<b>.
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For multiplication by powers of 2, use L<BN_lshift(3)|BN_lshift(3)>.
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BN_div() divides B<a> by B<d> and places the result in B<dv> and the
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remainder in B<rem> (C<dv=a/d, rem=a%d>). Either of B<dv> and B<rem> may
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be NULL, in which case the respective value is not returned.
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For division by powers of 2, use BN_rshift(3).
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BN_sqr() takes the square of B<a> and places the result in B<r>
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(C<r=a^2>). B<r> and B<a> may be the same B<BIGNUM>.
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This function is faster than BN_mul(r,a,a).
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BN_mod() find the remainder of B<a> divided by B<m> and places it in
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B<rem> (C<rem=a%m>).
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BN_mod_mul() multiplies B<a> by B<b> and finds the remainder when
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divided by B<m> (C<r=(a*b)%m>). B<r> may be the same B<BIGNUM> as B<a>
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or B<b>. For a more efficient algorithm, see
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L<BN_mod_mul_montgomery(3)|BN_mod_mul_montgomery(3)>; for repeated
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computations using the same modulus, see L<BN_mod_mul_reciprocal(3)|BN_mod_mul_reciprocal(3)>.
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BN_exp() raises B<a> to the B<p>-th power and places the result in B<r>
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(C<r=a^p>). This function is faster than repeated applications of
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BN_mul().
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BN_mod_exp() computes B<a> to the B<p>-th power modulo B<m> (C<r=a^p %
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m>). This function uses less time and space than BN_exp().
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BN_gcd() computes the greatest common divisor of B<a> and B<b> and
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places the result in B<r>. B<r> may be the same B<BIGNUM> as B<a> or
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B<b>.
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For all functions, B<ctx> is a previously allocated B<BN_CTX> used for
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temporary variables; see L<BN_CTX_new(3)|BN_CTX_new(3)>.
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Unless noted otherwise, the result B<BIGNUM> must be different from
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the arguments.
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=head1 RETURN VALUES
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For all functions, 1 is returned for success, 0 on error. The return
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value should always be checked (e.g., C<if (!BN_add(r,a,b)) goto err;>).
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The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
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=head1 SEE ALSO
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L<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<BN_CTX_new(3)|BN_CTX_new(3)>,
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L<BN_add_word(3)|BN_add_word(3)>, L<BN_set_bit(3)|BN_set_bit(3)>
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=head1 HISTORY
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BN_add(), BN_sub(), BN_div(), BN_sqr(), BN_mod(), BN_mod_mul(),
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BN_mod_exp() and BN_gcd() are available in all versions of SSLeay and
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OpenSSL. The B<ctx> argument to BN_mul() was added in SSLeay
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0.9.1b. BN_exp() appeared in SSLeay 0.9.0.
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=cut
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