f987a4dd89
The manual pages require for some API functions that the 'random number
generator must be seeded' before calling the function. Initially, this
was meant literally, i.e. the OpenSSL CSPRNG had to be seeded manually
before calling these functions.
Since version 1.1.1, the CSPRNG is seeded automatically on first use,
so it's not the responsibility of the programmer anymore. Still, he
needs to be aware that the seeding might fail.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/9257)
(cherry picked from commit 262c00882a)
110 lines
3.4 KiB
Text
110 lines
3.4 KiB
Text
=pod
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=head1 NAME
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RSA_generate_key_ex, RSA_generate_key,
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RSA_generate_multi_prime_key - generate RSA key pair
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=head1 SYNOPSIS
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#include <openssl/rsa.h>
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int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
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int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb);
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Deprecated:
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#if OPENSSL_API_COMPAT < 0x00908000L
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RSA *RSA_generate_key(int bits, unsigned long e,
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void (*callback)(int, int, void *), void *cb_arg);
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#endif
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=head1 DESCRIPTION
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RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in the
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B<RSA> structure provided in B<rsa>. The pseudo-random number generator must
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be seeded prior to calling RSA_generate_key_ex().
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RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores
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it in the B<RSA> structure provided in B<rsa>. The number of primes is given by
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the B<primes> parameter. The random number generator must be seeded when
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calling RSA_generate_multi_prime_key().
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If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
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external circumstances (see L<RAND(7)>), the operation will fail.
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The modulus size will be of length B<bits>, the number of primes to form the
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modulus will be B<primes>, and the public exponent will be B<e>. Key sizes
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with B<num> E<lt> 1024 should be considered insecure. The exponent is an odd
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number, typically 3, 17 or 65537.
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In order to maintain adequate security level, the maximum number of permitted
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B<primes> depends on modulus bit length:
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<1024 | >=1024 | >=4096 | >=8192
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------+--------+--------+-------
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2 | 3 | 4 | 5
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A callback function may be used to provide feedback about the
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progress of the key generation. If B<cb> is not B<NULL>, it
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will be called as follows using the BN_GENCB_call() function
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described on the L<BN_generate_prime(3)> page.
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RSA_generate_key() is similar to RSA_generate_key_ex() but
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expects an old-style callback function; see
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L<BN_generate_prime(3)> for information on the old-style callback.
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=over 2
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=item *
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While a random prime number is generated, it is called as
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described in L<BN_generate_prime(3)>.
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=item *
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When the n-th randomly generated prime is rejected as not
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suitable for the key, B<BN_GENCB_call(cb, 2, n)> is called.
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=item *
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When a random p has been found with p-1 relatively prime to B<e>,
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it is called as B<BN_GENCB_call(cb, 3, 0)>.
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=back
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The process is then repeated for prime q and other primes (if any)
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with B<BN_GENCB_call(cb, 3, i)> where B<i> indicates the i-th prime.
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=head1 RETURN VALUES
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RSA_generate_multi_prime_key() returns 1 on success or 0 on error.
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RSA_generate_key_ex() returns 1 on success or 0 on error.
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The error codes can be obtained by L<ERR_get_error(3)>.
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RSA_generate_key() returns a pointer to the RSA structure or
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B<NULL> if the key generation fails.
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=head1 BUGS
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B<BN_GENCB_call(cb, 2, x)> is used with two different meanings.
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=head1 SEE ALSO
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L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)>,
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L<RAND(7)>
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=head1 HISTORY
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RSA_generate_key() was deprecated in OpenSSL 0.9.8; use
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RSA_generate_key_ex() instead.
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=head1 COPYRIGHT
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Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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