=pod =head1 NAME RSA_generate_key_ex, RSA_generate_key, RSA_generate_multi_prime_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); int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb); Deprecated: #if OPENSSL_API_COMPAT < 0x00908000L RSA *RSA_generate_key(int num, unsigned long e, void (*callback)(int, int, void *), void *cb_arg); #endif =head1 DESCRIPTION RSA_generate_key_ex() generates a 2-prime RSA 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(). RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores it in the B<RSA> structure provided in B<rsa>. The number of primes is given by the B<primes> parameter. The pseudo-random number generator must be seeded prior to calling RSA_generate_multi_prime_key(). The modulus size will be of length B<bits>, the number of primes to form the modulus will be B<primes>, 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. In order to maintain adequate security level, the maximum number of permitted B<primes> depends on modulus bit length: <1024 | >=1024 | >=4096 | >=8192 ------+--------+--------+------- 2 | 3 | 4 | 5 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)> page. RSA_generate_prime() is similar to RSA_generate_prime_ex() but expects an old-style callback function; see L<BN_generate_prime(3)> for information on the old-style callback. =over 2 =item * While a random prime number is generated, it is called as described in L<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 and other primes (if any) with B<BN_GENCB_call(cb, 3, i)> where B<i> indicates the i-th prime. =head1 RETURN VALUES RSA_generate_multi_prime_key() returns 1 on success or 0 on error. RSA_generate_key_ex() returns 1 on success or 0 on error. The error codes can be obtained by L<ERR_get_error(3)>. RSA_generate_key() returns a pointer to the RSA structure or B<NULL> if the key generation fails. =head1 BUGS B<BN_GENCB_call(cb, 2, x)> is used with two different meanings. =head1 SEE ALSO L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)> =head1 HISTORY RSA_generate_key() was deprecated in OpenSSL 0.9.8; use RSA_generate_key_ex() instead. =head1 COPYRIGHT Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at L<https://www.openssl.org/source/license.html>. =cut