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RSA_check_key(3)                                   OpenSSL                                  RSA_check_key(3)



NAME
       RSA_check_key - validate private RSA keys

SYNOPSIS
        #include <openssl/rsa.h>

        int RSA_check_key(RSA *rsa);

DESCRIPTION
       This function validates RSA keys. It checks that p and q are in fact prime, and that n = p*q.

       It also checks that d*e = 1 mod (p-1*q-1), and that dmp1, dmq1 and iqmp are set correctly or are
       NULL.

       As such, this function can not be used with any arbitrary RSA key object, even if it is otherwise fit
       for regular RSA operation. See NOTES for more information.

RETURN VALUE
       RSA_check_key() returns 1 if rsa is a valid RSA key, and 0 otherwise.  -1 is returned if an error
       occurs while checking the key.

       If the key is invalid or an error occurred, the reason code can be obtained using ERR_get_error(3).

NOTES
       This function does not work on RSA public keys that have only the modulus and public exponent
       elements populated. It performs integrity checks on all the RSA key material, so the RSA key
       structure must contain all the private key data too.

       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.

BUGS
       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.

SEE ALSO
       rsa(3), ERR_get_error(3)

HISTORY
       RSA_check_key() appeared in OpenSSL 0.9.4.



0.9.8                                            2009-04-03                                 RSA_check_key(3)