| 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_check_key_ex, RSA_check_key - validate private RSA keys
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/rsa.h>
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| 10 |
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| 11 | int RSA_check_key_ex(RSA *rsa, BN_GENCB *cb);
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| 12 |
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| 13 | int RSA_check_key(RSA *rsa);
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| 14 |
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| 15 | =head1 DESCRIPTION
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| 16 |
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| 17 | RSA_check_key_ex() function validates RSA keys.
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| 18 | It checks that B<p> and B<q> are
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| 19 | in fact prime, and that B<n = p*q>.
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| 20 |
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| 21 | It does not work on RSA public keys that have only the modulus
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| 22 | and public exponent elements populated.
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| 23 | It also checks that B<d*e = 1 mod (p-1*q-1)>,
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| 24 | and that B<dmp1>, B<dmq1> and B<iqmp> are set correctly or are B<NULL>.
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| 25 | It performs integrity checks on all
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| 26 | the RSA key material, so the RSA key structure must contain all the private
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| 27 | key data too.
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| 28 | Therefore, it cannot be used with any arbitrary RSA key object,
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| 29 | even if it is otherwise fit for regular RSA operation.
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| 30 |
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| 31 | The B<cb> parameter is a callback that will be invoked in the same
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| 32 | manner as L<BN_is_prime_ex(3)>.
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| 33 |
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| 34 | RSA_check_key() is equivalent to RSA_check_key_ex() with a NULL B<cb>.
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| 35 |
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| 36 | =head1 RETURN VALUES
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| 37 |
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| 38 | RSA_check_key_ex() and RSA_check_key()
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| 39 | return 1 if B<rsa> is a valid RSA key, and 0 otherwise.
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| 40 | They return -1 if an error occurs while checking the key.
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| 41 |
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| 42 | If the key is invalid or an error occurred, the reason code can be
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| 43 | obtained using L<ERR_get_error(3)>.
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| 44 |
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| 45 | =head1 NOTES
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| 46 |
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| 47 | Unlike most other RSA functions, this function does B<not> work
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| 48 | transparently with any underlying ENGINE implementation because it uses the
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| 49 | key data in the RSA structure directly. An ENGINE implementation can
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| 50 | override the way key data is stored and handled, and can even provide
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| 51 | support for HSM keys - in which case the RSA structure may contain B<no>
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| 52 | key data at all! If the ENGINE in question is only being used for
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| 53 | acceleration or analysis purposes, then in all likelihood the RSA key data
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| 54 | is complete and untouched, but this can't be assumed in the general case.
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| 55 |
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| 56 | =head1 BUGS
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| 57 |
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| 58 | A method of verifying the RSA key using opaque RSA API functions might need
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| 59 | to be considered. Right now RSA_check_key() simply uses the RSA structure
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| 60 | elements directly, bypassing the RSA_METHOD table altogether (and
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| 61 | completely violating encapsulation and object-orientation in the process).
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| 62 | The best fix will probably be to introduce a "check_key()" handler to the
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| 63 | RSA_METHOD function table so that alternative implementations can also
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| 64 | provide their own verifiers.
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| 65 |
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| 66 | =head1 SEE ALSO
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| 67 |
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| 68 | L<BN_is_prime_ex(3)>,
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| 69 | L<ERR_get_error(3)>
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| 70 |
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| 71 | =head1 HISTORY
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| 72 |
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| 73 | RSA_check_key_ex() appeared after OpenSSL 1.0.2.
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| 74 |
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| 75 | =head1 COPYRIGHT
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| 76 |
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| 77 | Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
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| 78 |
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| 79 | Licensed under the OpenSSL license (the "License"). You may not use
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| 80 | this file except in compliance with the License. You can obtain a copy
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| 81 | in the file LICENSE in the source distribution or at
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| 82 | L<https://www.openssl.org/source/license.html>.
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| 83 |
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| 84 | =cut
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