1=pod 2 3=head1 NAME 4 5RSA_generate_key_ex, RSA_generate_key, 6RSA_generate_multi_prime_key - generate RSA key pair 7 8=head1 SYNOPSIS 9 10 #include <openssl/rsa.h> 11 12 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb); 13 int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb); 14 15Deprecated: 16 17 #if OPENSSL_API_COMPAT < 0x00908000L 18 RSA *RSA_generate_key(int num, unsigned long e, 19 void (*callback)(int, int, void *), void *cb_arg); 20 #endif 21 22=head1 DESCRIPTION 23 24RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in the 25B<RSA> structure provided in B<rsa>. The pseudo-random number generator must 26be seeded prior to calling RSA_generate_key_ex(). 27 28RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores 29it in the B<RSA> structure provided in B<rsa>. The number of primes is given by 30the B<primes> parameter. The pseudo-random number generator must be seeded prior 31to calling RSA_generate_multi_prime_key(). 32 33The modulus size will be of length B<bits>, the number of primes to form the 34modulus will be B<primes>, and the public exponent will be B<e>. Key sizes 35with B<num> E<lt> 1024 should be considered insecure. The exponent is an odd 36number, typically 3, 17 or 65537. 37 38In order to maintain adequate security level, the maximum number of permitted 39B<primes> depends on modulus bit length: 40 41 <1024 | >=1024 | >=4096 | >=8192 42 ------+--------+--------+------- 43 2 | 3 | 4 | 5 44 45A callback function may be used to provide feedback about the 46progress of the key generation. If B<cb> is not B<NULL>, it 47will be called as follows using the BN_GENCB_call() function 48described on the L<BN_generate_prime(3)> page. 49 50RSA_generate_prime() is similar to RSA_generate_prime_ex() but 51expects an old-style callback function; see 52L<BN_generate_prime(3)> for information on the old-style callback. 53 54=over 2 55 56=item * 57 58While a random prime number is generated, it is called as 59described in L<BN_generate_prime(3)>. 60 61=item * 62 63When the n-th randomly generated prime is rejected as not 64suitable for the key, B<BN_GENCB_call(cb, 2, n)> is called. 65 66=item * 67 68When a random p has been found with p-1 relatively prime to B<e>, 69it is called as B<BN_GENCB_call(cb, 3, 0)>. 70 71=back 72 73The process is then repeated for prime q and other primes (if any) 74with B<BN_GENCB_call(cb, 3, i)> where B<i> indicates the i-th prime. 75 76=head1 RETURN VALUES 77 78RSA_generate_multi_prime_key() returns 1 on success or 0 on error. 79RSA_generate_key_ex() returns 1 on success or 0 on error. 80The error codes can be obtained by L<ERR_get_error(3)>. 81 82RSA_generate_key() returns a pointer to the RSA structure or 83B<NULL> if the key generation fails. 84 85=head1 BUGS 86 87B<BN_GENCB_call(cb, 2, x)> is used with two different meanings. 88 89=head1 SEE ALSO 90 91L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)> 92 93=head1 HISTORY 94 95RSA_generate_key() was deprecated in OpenSSL 0.9.8; use 96RSA_generate_key_ex() instead. 97 98=head1 COPYRIGHT 99 100Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. 101 102Licensed under the OpenSSL license (the "License"). You may not use 103this file except in compliance with the License. You can obtain a copy 104in the file LICENSE in the source distribution or at 105L<https://www.openssl.org/source/license.html>. 106 107=cut 108