openssl1.0/doc/crypto/RSA_generate_key.pod
2019-08-09 10:00:55 +02:00

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=pod
=head1 NAME
RSA_generate_key_ex, RSA_generate_key - generate RSA key pair
=head1 SYNOPSIS
#include <openssl/rsa.h>
int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
Deprecated:
RSA *RSA_generate_key(int num, unsigned long e,
void (*callback)(int,int,void *), void *cb_arg);
=head1 DESCRIPTION
RSA_generate_key_ex() generates a key pair and stores it in the B<RSA>
structure provided in B<rsa>. The pseudo-random number generator must
be seeded prior to calling RSA_generate_key_ex().
The modulus size will be of length B<bits>, and the public exponent will be
B<e>. Key sizes with B<num> E<lt> 1024 should be considered insecure.
The exponent is an odd number, typically 3, 17 or 65537.
A callback function may be used to provide feedback about the
progress of the key generation. If B<cb> is not B<NULL>, it
will be called as follows using the BN_GENCB_call() function
described on the L<BN_generate_prime(3)|BN_generate_prime(3)> page.
=over 4
=item *
While a random prime number is generated, it is called as
described in L<BN_generate_prime(3)|BN_generate_prime(3)>.
=item *
When the n-th randomly generated prime is rejected as not
suitable for the key, B<BN_GENCB_call(cb, 2, n)> is called.
=item *
When a random p has been found with p-1 relatively prime to B<e>,
it is called as B<BN_GENCB_call(cb, 3, 0)>.
=back
The process is then repeated for prime q with B<BN_GENCB_call(cb, 3, 1)>.
RSA_generate_key is deprecated (new applications should use
RSA_generate_key_ex instead). RSA_generate_key works in the same way as
RSA_generate_key_ex except it uses "old style" call backs. See
L<BN_generate_prime(3)|BN_generate_prime(3)> for further details.
=head1 RETURN VALUE
If key generation fails, RSA_generate_key() returns B<NULL>.
The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
=head1 BUGS
B<BN_GENCB_call(cb, 2, x)> is used with two different meanings.
RSA_generate_key() goes into an infinite loop for illegal input values.
=head1 SEE ALSO
L<ERR_get_error(3)|ERR_get_error(3)>, L<rand(3)|rand(3)>, L<rsa(3)|rsa(3)>,
L<RSA_free(3)|RSA_free(3)>, L<BN_generate_prime(3)|BN_generate_prime(3)>
=head1 HISTORY
The B<cb_arg> argument was added in SSLeay 0.9.0.
=cut