a528d4f0a9
If something was "present in all versions" of SSLeay, or if it was added to a version of SSLeay (and therefore predates OpenSSL), remove mention of it. Documentation history now starts with OpenSSL. Remove mention of all history before OpenSSL 0.9.8, inclusive. Remove all AUTHOR sections. Reviewed-by: Tim Hudson <tjh@openssl.org>
183 lines
6 KiB
Text
183 lines
6 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
BN_generate_prime_ex, BN_is_prime_ex, BN_is_prime_fasttest_ex, BN_GENCB_call,
|
|
BN_GENCB_new, BN_GENCB_free, BN_GENCB_set_old, BN_GENCB_set, BN_GENCB_get_arg,
|
|
BN_generate_prime, BN_is_prime, BN_is_prime_fasttest - generate primes and test
|
|
for primality
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/bn.h>
|
|
|
|
int BN_generate_prime_ex(BIGNUM *ret,int bits,int safe, const BIGNUM *add,
|
|
const BIGNUM *rem, BN_GENCB *cb);
|
|
|
|
int BN_is_prime_ex(const BIGNUM *p,int nchecks, BN_CTX *ctx, BN_GENCB *cb);
|
|
|
|
int BN_is_prime_fasttest_ex(const BIGNUM *p,int nchecks, BN_CTX *ctx,
|
|
int do_trial_division, BN_GENCB *cb);
|
|
|
|
int BN_GENCB_call(BN_GENCB *cb, int a, int b);
|
|
|
|
BN_GENCB *BN_GENCB_new(void);
|
|
|
|
void BN_GENCB_free(BN_GENCB *cb);
|
|
|
|
void BN_GENCB_set_old(BN_GENCB *gencb,
|
|
void (*callback)(int, int, void *), void *cb_arg);
|
|
|
|
void BN_GENCB_set(BN_GENCB *gencb,
|
|
int (*callback)(int, int, BN_GENCB *), void *cb_arg);
|
|
|
|
void *BN_GENCB_get_arg(BN_GENCB *cb);
|
|
|
|
Deprecated:
|
|
|
|
BIGNUM *BN_generate_prime(BIGNUM *ret, int num, int safe, BIGNUM *add,
|
|
BIGNUM *rem, void (*callback)(int, int, void *), void *cb_arg);
|
|
|
|
int BN_is_prime(const BIGNUM *a, int checks, void (*callback)(int, int,
|
|
void *), BN_CTX *ctx, void *cb_arg);
|
|
|
|
int BN_is_prime_fasttest(const BIGNUM *a, int checks,
|
|
void (*callback)(int, int, void *), BN_CTX *ctx, void *cb_arg,
|
|
int do_trial_division);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
BN_generate_prime_ex() generates a pseudo-random prime number of
|
|
at least bit length B<bits>.
|
|
If B<ret> is not B<NULL>, it will be used to store the number.
|
|
|
|
If B<cb> is not B<NULL>, it is used as follows:
|
|
|
|
=over 4
|
|
|
|
=item *
|
|
|
|
B<BN_GENCB_call(cb, 0, i)> is called after generating the i-th
|
|
potential prime number.
|
|
|
|
=item *
|
|
|
|
While the number is being tested for primality,
|
|
B<BN_GENCB_call(cb, 1, j)> is called as described below.
|
|
|
|
=item *
|
|
|
|
When a prime has been found, B<BN_GENCB_call(cb, 2, i)> is called.
|
|
|
|
=back
|
|
|
|
The prime may have to fulfill additional requirements for use in
|
|
Diffie-Hellman key exchange:
|
|
|
|
If B<add> is not B<NULL>, the prime will fulfill the condition p % B<add>
|
|
== B<rem> (p % B<add> == 1 if B<rem> == B<NULL>) in order to suit a given
|
|
generator.
|
|
|
|
If B<safe> is true, it will be a safe prime (i.e. a prime p so
|
|
that (p-1)/2 is also prime).
|
|
|
|
The PRNG must be seeded prior to calling BN_generate_prime_ex().
|
|
The prime number generation has a negligible error probability.
|
|
|
|
BN_is_prime_ex() and BN_is_prime_fasttest_ex() test if the number B<p> is
|
|
prime. The following tests are performed until one of them shows that
|
|
B<p> is composite; if B<p> passes all these tests, it is considered
|
|
prime.
|
|
|
|
BN_is_prime_fasttest_ex(), when called with B<do_trial_division == 1>,
|
|
first attempts trial division by a number of small primes;
|
|
if no divisors are found by this test and B<cb> is not B<NULL>,
|
|
B<BN_GENCB_call(cb, 1, -1)> is called.
|
|
If B<do_trial_division == 0>, this test is skipped.
|
|
|
|
Both BN_is_prime_ex() and BN_is_prime_fasttest_ex() perform a Miller-Rabin
|
|
probabilistic primality test with B<nchecks> iterations. If
|
|
B<nchecks == BN_prime_checks>, a number of iterations is used that
|
|
yields a false positive rate of at most 2^-80 for random input.
|
|
|
|
If B<cb> is not B<NULL>, B<BN_GENCB_call(cb, 1, j)> is called
|
|
after the j-th iteration (j = 0, 1, ...). B<ctx> is a
|
|
pre-allocated B<BN_CTX> (to save the overhead of allocating and
|
|
freeing the structure in a loop), or B<NULL>.
|
|
|
|
BN_GENCB_call calls the callback function held in the B<BN_GENCB> structure
|
|
and passes the ints B<a> and B<b> as arguments. There are two types of
|
|
B<BN_GENCB> structure that are supported: "new" style and "old" style. New
|
|
programs should prefer the "new" style, whilst the "old" style is provided
|
|
for backwards compatibility purposes.
|
|
|
|
A BN_GENCB structure should be created through a call to BN_GENCB_new(),
|
|
and freed through a call to BN_GENCB_free().
|
|
|
|
For "new" style callbacks a BN_GENCB structure should be initialised with a
|
|
call to BN_GENCB_set(), where B<gencb> is a B<BN_GENCB *>, B<callback> is of
|
|
type B<int (*callback)(int, int, BN_GENCB *)> and B<cb_arg> is a B<void *>.
|
|
"Old" style callbacks are the same except they are initialised with a call
|
|
to BN_GENCB_set_old() and B<callback> is of type
|
|
B<void (*callback)(int, int, void *)>.
|
|
|
|
A callback is invoked through a call to B<BN_GENCB_call>. This will check
|
|
the type of the callback and will invoke B<callback(a, b, gencb)> for new
|
|
style callbacks or B<callback(a, b, cb_arg)> for old style.
|
|
|
|
It is possible to obtained the argument associated with a BN_GENCB structure
|
|
(set via a call to BN_GENCB_set or BN_GENCB_set_old) using BN_GENCB_get_arg.
|
|
|
|
BN_generate_prime (deprecated) works in the same way as
|
|
BN_generate_prime_ex but expects an old style callback function
|
|
directly in the B<callback> parameter, and an argument to pass to it in
|
|
the B<cb_arg>. Similarly BN_is_prime and BN_is_prime_fasttest are
|
|
deprecated and can be compared to BN_is_prime_ex and
|
|
BN_is_prime_fasttest_ex respectively.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
BN_generate_prime_ex() return 1 on success or 0 on error.
|
|
|
|
BN_is_prime_ex(), BN_is_prime_fasttest_ex(), BN_is_prime() and
|
|
BN_is_prime_fasttest() return 0 if the number is composite, 1 if it is
|
|
prime with an error probability of less than 0.25^B<nchecks>, and
|
|
-1 on error.
|
|
|
|
BN_generate_prime() returns the prime number on success, B<NULL> otherwise.
|
|
|
|
BN_GENCB_new returns a pointer to a BN_GENCB structure on success, or B<NULL>
|
|
otherwise.
|
|
|
|
BN_GENCB_get_arg returns the argument previously associated with a BN_GENCB
|
|
structure.
|
|
|
|
Callback functions should return 1 on success or 0 on error.
|
|
|
|
The error codes can be obtained by L<ERR_get_error(3)>.
|
|
|
|
=head1 REMOVED FUNCTIONALITY
|
|
|
|
As of OpenSSL 1.1.0 it is no longer possible to create a BN_GENCB structure
|
|
directly, as in:
|
|
|
|
BN_GENCB callback;
|
|
|
|
Instead applications should create a BN_GENCB structure using BN_GENCB_new:
|
|
|
|
BN_GENCB *callback;
|
|
callback = BN_GENCB_new();
|
|
if(!callback) /* handle error */
|
|
...
|
|
BN_GENCB_free(callback);
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<bn(3)>, L<ERR_get_error(3)>, L<rand(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
BN_GENCB_new(), BN_GENCB_free(),
|
|
and BN_GENCB_get_arg() were added in OpenSSL 1.1.0
|
|
|
|
=cut
|