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 bits, 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 random number generator must be seeded when 31calling RSA_generate_multi_prime_key(). 32If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to 33external circumstances (see L<RAND(7)>), the operation will fail. 34 35The modulus size will be of length B<bits>, the number of primes to form the 36modulus will be B<primes>, and the public exponent will be B<e>. Key sizes 37with B<num> E<lt> 1024 should be considered insecure. The exponent is an odd 38number, typically 3, 17 or 65537. 39 40In order to maintain adequate security level, the maximum number of permitted 41B<primes> depends on modulus bit length: 42 43 <1024 | >=1024 | >=4096 | >=8192 44 ------+--------+--------+------- 45 2 | 3 | 4 | 5 46 47A callback function may be used to provide feedback about the 48progress of the key generation. If B<cb> is not B<NULL>, it 49will be called as follows using the BN_GENCB_call() function 50described on the L<BN_generate_prime(3)> page. 51 52RSA_generate_key() is similar to RSA_generate_key_ex() but 53expects an old-style callback function; see 54L<BN_generate_prime(3)> for information on the old-style callback. 55 56=over 2 57 58=item * 59 60While a random prime number is generated, it is called as 61described in L<BN_generate_prime(3)>. 62 63=item * 64 65When the n-th randomly generated prime is rejected as not 66suitable for the key, B<BN_GENCB_call(cb, 2, n)> is called. 67 68=item * 69 70When a random p has been found with p-1 relatively prime to B<e>, 71it is called as B<BN_GENCB_call(cb, 3, 0)>. 72 73=back 74 75The process is then repeated for prime q and other primes (if any) 76with B<BN_GENCB_call(cb, 3, i)> where B<i> indicates the i-th prime. 77 78=head1 RETURN VALUES 79 80RSA_generate_multi_prime_key() returns 1 on success or 0 on error. 81RSA_generate_key_ex() returns 1 on success or 0 on error. 82The error codes can be obtained by L<ERR_get_error(3)>. 83 84RSA_generate_key() returns a pointer to the RSA structure or 85B<NULL> if the key generation fails. 86 87=head1 BUGS 88 89B<BN_GENCB_call(cb, 2, x)> is used with two different meanings. 90 91=head1 SEE ALSO 92 93L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)>, 94L<RAND(7)> 95 96=head1 HISTORY 97 98RSA_generate_key() was deprecated in OpenSSL 0.9.8; use 99RSA_generate_key_ex() instead. 100 101=head1 COPYRIGHT 102 103Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. 104 105Licensed under the OpenSSL license (the "License"). You may not use 106this file except in compliance with the License. You can obtain a copy 107in the file LICENSE in the source distribution or at 108L<https://www.openssl.org/source/license.html>. 109 110=cut 111