| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | RSA_generate_key_ex, RSA_generate_key,
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| 6 | RSA_generate_multi_prime_key - generate RSA key pair
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| 7 |
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| 8 | =head1 SYNOPSIS
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| 9 |
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| 10 | #include <openssl/rsa.h>
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| 11 |
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| 12 | int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
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| 13 | int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb);
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| 14 |
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| 15 | Deprecated:
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| 16 |
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| 17 | #if OPENSSL_API_COMPAT < 0x00908000L
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| 18 | RSA *RSA_generate_key(int bits, unsigned long e,
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| 19 | void (*callback)(int, int, void *), void *cb_arg);
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| 20 | #endif
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| 21 |
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| 22 | =head1 DESCRIPTION
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| 23 |
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| 24 | RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in the
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| 25 | B<RSA> structure provided in B<rsa>. The pseudo-random number generator must
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| 26 | be seeded prior to calling RSA_generate_key_ex().
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| 27 |
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| 28 | RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores
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| 29 | it in the B<RSA> structure provided in B<rsa>. The number of primes is given by
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| 30 | the B<primes> parameter. The random number generator must be seeded when
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| 31 | calling RSA_generate_multi_prime_key().
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| 32 | If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
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| 33 | external circumstances (see L<RAND(7)>), the operation will fail.
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| 34 |
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| 35 | The modulus size will be of length B<bits>, the number of primes to form the
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| 36 | modulus will be B<primes>, and the public exponent will be B<e>. Key sizes
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| 37 | with B<num> E<lt> 1024 should be considered insecure. The exponent is an odd
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| 38 | number, typically 3, 17 or 65537.
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| 39 |
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| 40 | In order to maintain adequate security level, the maximum number of permitted
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| 41 | B<primes> depends on modulus bit length:
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| 42 |
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| 43 | <1024 | >=1024 | >=4096 | >=8192
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| 44 | ------+--------+--------+-------
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| 45 | 2 | 3 | 4 | 5
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| 46 |
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| 47 | A callback function may be used to provide feedback about the
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| 48 | progress of the key generation. If B<cb> is not B<NULL>, it
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| 49 | will be called as follows using the BN_GENCB_call() function
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| 50 | described on the L<BN_generate_prime(3)> page.
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| 51 |
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| 52 | RSA_generate_key() is similar to RSA_generate_key_ex() but
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| 53 | expects an old-style callback function; see
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| 54 | L<BN_generate_prime(3)> for information on the old-style callback.
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| 55 |
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| 56 | =over 2
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| 57 |
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| 58 | =item *
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| 59 |
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| 60 | While a random prime number is generated, it is called as
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| 61 | described in L<BN_generate_prime(3)>.
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| 62 |
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| 63 | =item *
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| 64 |
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| 65 | When the n-th randomly generated prime is rejected as not
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| 66 | suitable for the key, B<BN_GENCB_call(cb, 2, n)> is called.
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| 67 |
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| 68 | =item *
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| 69 |
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| 70 | When a random p has been found with p-1 relatively prime to B<e>,
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| 71 | it is called as B<BN_GENCB_call(cb, 3, 0)>.
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| 72 |
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| 73 | =back
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| 74 |
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| 75 | The process is then repeated for prime q and other primes (if any)
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| 76 | with B<BN_GENCB_call(cb, 3, i)> where B<i> indicates the i-th prime.
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| 77 |
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| 78 | =head1 RETURN VALUES
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| 79 |
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| 80 | RSA_generate_multi_prime_key() returns 1 on success or 0 on error.
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| 81 | RSA_generate_key_ex() returns 1 on success or 0 on error.
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| 82 | The error codes can be obtained by L<ERR_get_error(3)>.
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| 83 |
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| 84 | RSA_generate_key() returns a pointer to the RSA structure or
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| 85 | B<NULL> if the key generation fails.
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| 86 |
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| 87 | =head1 BUGS
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| 88 |
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| 89 | B<BN_GENCB_call(cb, 2, x)> is used with two different meanings.
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| 90 |
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| 91 | =head1 SEE ALSO
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| 92 |
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| 93 | L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)>,
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| 94 | L<RAND(7)>
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| 95 |
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| 96 | =head1 HISTORY
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| 97 |
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| 98 | RSA_generate_key() was deprecated in OpenSSL 0.9.8; use
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| 99 | RSA_generate_key_ex() instead.
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| 100 |
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| 101 | =head1 COPYRIGHT
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| 102 |
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| 103 | Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
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| 104 |
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| 105 | Licensed under the OpenSSL license (the "License"). You may not use
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| 106 | this file except in compliance with the License. You can obtain a copy
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| 107 | in the file LICENSE in the source distribution or at
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| 108 | L<https://www.openssl.org/source/license.html>.
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| 109 |
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| 110 | =cut
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