1=pod 2 3=head1 NAME 4 5EVP_RSA_gen, 6RSA_generate_key_ex, RSA_generate_key, 7RSA_generate_multi_prime_key - generate RSA key pair 8 9=head1 SYNOPSIS 10 11 #include <openssl/rsa.h> 12 13 EVP_PKEY *EVP_RSA_gen(unsigned int bits); 14 15Deprecated since OpenSSL 3.0, can be hidden entirely by defining 16B<OPENSSL_API_COMPAT> with a suitable version value, see 17L<openssl_user_macros(7)>: 18 19 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb); 20 int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb); 21 22Deprecated since OpenSSL 0.9.8: 23 24 RSA *RSA_generate_key(int bits, unsigned long e, 25 void (*callback)(int, int, void *), void *cb_arg); 26 27=head1 DESCRIPTION 28 29EVP_RSA_gen() generates a new RSA key pair with modulus size I<bits>. 30 31All of the functions described below are deprecated. 32Applications should instead use EVP_RSA_gen(), L<EVP_PKEY_Q_keygen(3)>, or 33L<EVP_PKEY_keygen_init(3)> and L<EVP_PKEY_keygen(3)>. 34 35RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in the 36B<RSA> structure provided in I<rsa>. 37 38RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores 39it in the B<RSA> structure provided in I<rsa>. The number of primes is given by 40the I<primes> parameter. 41If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to 42external circumstances (see L<RAND(7)>), the operation will fail. 43 44The modulus size will be of length I<bits>, the number of primes to form the 45modulus will be I<primes>, and the public exponent will be I<e>. Key sizes 46with I<num> E<lt> 1024 should be considered insecure. The exponent is an odd 47number, typically 3, 17 or 65537. 48 49In order to maintain adequate security level, the maximum number of permitted 50I<primes> depends on modulus bit length: 51 52 <1024 | >=1024 | >=4096 | >=8192 53 ------+--------+--------+------- 54 2 | 3 | 4 | 5 55 56A callback function may be used to provide feedback about the 57progress of the key generation. If I<cb> is not NULL, it 58will be called as follows using the BN_GENCB_call() function 59described on the L<BN_generate_prime(3)> page. 60 61RSA_generate_key() is similar to RSA_generate_key_ex() but 62expects an old-style callback function; see 63L<BN_generate_prime(3)> for information on the old-style callback. 64 65=over 2 66 67=item * 68 69While a random prime number is generated, it is called as 70described in L<BN_generate_prime(3)>. 71 72=item * 73 74When the n-th randomly generated prime is rejected as not 75suitable for the key, I<BN_GENCB_call(cb, 2, n)> is called. 76 77=item * 78 79When a random p has been found with p-1 relatively prime to I<e>, 80it is called as I<BN_GENCB_call(cb, 3, 0)>. 81 82=back 83 84The process is then repeated for prime q and other primes (if any) 85with I<BN_GENCB_call(cb, 3, i)> where I<i> indicates the i-th prime. 86 87=head1 RETURN VALUES 88 89EVP_RSA_gen() returns an I<EVP_PKEY> or NULL on failure. 90 91RSA_generate_multi_prime_key() returns 1 on success or 0 on error. 92RSA_generate_key_ex() returns 1 on success or 0 on error. 93The error codes can be obtained by L<ERR_get_error(3)>. 94 95RSA_generate_key() returns a pointer to the RSA structure or 96NULL if the key generation fails. 97 98=head1 BUGS 99 100I<BN_GENCB_call(cb, 2, x)> is used with two different meanings. 101 102=head1 SEE ALSO 103 104L<EVP_PKEY_Q_keygen(3)> 105L<BN_generate_prime(3)>, L<ERR_get_error(3)>, 106L<RAND_bytes(3)>, L<RAND(7)> 107 108=head1 HISTORY 109 110EVP_RSA_gen() was added in OpenSSL 3.0. 111All other functions described here were deprecated in OpenSSL 3.0. 112For replacement see L<EVP_PKEY-RSA(7)>. 113 114=head1 COPYRIGHT 115 116Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 117 118Licensed under the Apache License 2.0 (the "License"). You may not use 119this file except in compliance with the License. You can obtain a copy 120in the file LICENSE in the source distribution or at 121L<https://www.openssl.org/source/license.html>. 122 123=cut 124