RSA_CHECK_KEY(3SSL) OpenSSL RSA_CHECK_KEY(3SSL)
RSA_check_key_ex, RSA_check_key - validate private RSA keys
int RSA_check_key_ex(RSA *rsa, BN_GENCB *cb);
int RSA_check_key(RSA *rsa);
RSA_check_key_ex() function validates RSA keys. It checks that p and q
are in fact prime, and that n = p*q.
It does not work on RSA public keys that have only the modulus and
public exponent elements populated. It also checks that d*e = 1 mod
(p-1*q-1), and that dmp1, dmq1 and iqmp are set correctly or are NULL.
It performs integrity checks on all the RSA key material, so the RSA
key structure must contain all the private key data too. Therefore, it
cannot be used with any arbitrary RSA key object, even if it is
otherwise fit for regular RSA operation.
The cb parameter is a callback that will be invoked in the same manner
RSA_check_key() is equivalent to RSA_check_key_ex() with a NULL cb.
RSA_check_key_ex() and RSA_check_key() return 1 if rsa is a valid RSA
key, and 0 otherwise. They return -1 if an error occurs while checking
If the key is invalid or an error occurred, the reason code can be
obtained using ERR_get_error(3).
Unlike most other RSA functions, this function does not work
transparently with any underlying ENGINE implementation because it uses
the key data in the RSA structure directly. An ENGINE implementation
can override the way key data is stored and handled, and can even
provide support for HSM keys - in which case the RSA structure may
contain no key data at all! If the ENGINE in question is only being
used for acceleration or analysis purposes, then in all likelihood the
RSA key data is complete and untouched, but this can't be assumed in
the general case.
A method of verifying the RSA key using opaque RSA API functions might
need to be considered. Right now RSA_check_key() simply uses the RSA
structure elements directly, bypassing the RSA_METHOD table altogether
(and completely violating encapsulation and object-orientation in the
process). The best fix will probably be to introduce a "check_key()"
handler to the RSA_METHOD function table so that alternative
implementations can also provide their own verifiers.
RSA_check_key_ex() appeared after OpenSSL 1.0.2.
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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
1.1.1 2022-03-09 RSA_CHECK_KEY(3SSL)
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