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153aecf91a
manual when the specific function is refered to in the current manual text. This correction was originally introduced in OpenBSD's tracking of OpenSSL.
127 lines
4.2 KiB
Plaintext
127 lines
4.2 KiB
Plaintext
=pod
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=head1 NAME
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BN_add, BN_sub, BN_mul, BN_sqr, BN_div, BN_mod, BN_nnmod, BN_mod_add,
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BN_mod_sub, BN_mod_mul, BN_mod_sqr, BN_exp, BN_mod_exp, BN_gcd -
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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_sqr(BIGNUM *r, BIGNUM *a, 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_mod(BIGNUM *rem, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
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int BN_nnmod(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx);
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int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
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BN_CTX *ctx);
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int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
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BN_CTX *ctx);
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int BN_mod_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, const BIGNUM *m,
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BN_CTX *ctx);
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int BN_mod_sqr(BIGNUM *r, BIGNUM *a, const BIGNUM *m, 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 I<a> and I<b> and places the result in I<r> (C<r=a+b>).
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I<r> may be the same B<BIGNUM> as I<a> or I<b>.
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BN_sub() subtracts I<b> from I<a> and places the result in I<r> (C<r=a-b>).
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BN_mul() multiplies I<a> and I<b> and places the result in I<r> (C<r=a*b>).
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I<r> may be the same B<BIGNUM> as I<a> or I<b>.
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For multiplication by powers of 2, use L<BN_lshift(3)|BN_lshift(3)>.
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BN_sqr() takes the square of I<a> and places the result in I<r>
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(C<r=a^2>). I<r> and I<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_div() divides I<a> by I<d> and places the result in I<dv> and the
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remainder in I<rem> (C<dv=a/d, rem=a%d>). Either of I<dv> and I<rem> may
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be B<NULL>, in which case the respective value is not returned.
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The result is rounded towards zero; thus if I<a> is negative, the
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remainder will be zero or negative.
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For division by powers of 2, use BN_rshift(3).
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BN_mod() corresponds to BN_div() with I<dv> set to B<NULL>.
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BN_nnmod() reduces I<a> modulo I<m> and places the non-negative
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remainder in I<r>.
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BN_mod_add() adds I<a> to I<b> modulo I<m> and places the non-negative
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result in I<r>.
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BN_mod_sub() subtracts I<b> from I<a> modulo I<m> and places the
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non-negative result in I<r>.
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BN_mod_mul() multiplies I<a> by I<b> and finds the non-negative
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remainder respective to modulus I<m> (C<r=(a*b) mod m>). I<r> may be
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the same B<BIGNUM> as I<a> or I<b>. For more efficient algorithms for
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repeated computations using the same modulus, see
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L<BN_mod_mul_montgomery(3)|BN_mod_mul_montgomery(3)> and
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L<BN_mod_mul_reciprocal(3)|BN_mod_mul_reciprocal(3)>.
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BN_mod_sqr() takes the square of I<a> modulo B<m> and places the
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result in I<r>.
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BN_exp() raises I<a> to the I<p>-th power and places the result in I<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 I<a> to the I<p>-th power modulo I<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 I<a> and I<b> and
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places the result in I<r>. I<r> may be the same B<BIGNUM> as I<a> or
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I<b>.
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For all functions, I<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_sqr(), BN_div(), 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 I<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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BN_nnmod(), BN_mod_add(), BN_mod_sub(), and BN_mod_sqr() were added in
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OpenSSL 0.9.7.
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=cut
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