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 arbi-
       trary 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 mate-
       rial, so the RSA key structure must contain all the pri-
       vate key data too.

       Unlike most other RSA functions, this function does not
       work transparently with any underlying ENGINE implemen-
       tation 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 ques-
       tion 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-orienta-
       tion 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.



0.9.7c                     2002-09-25          RSA_check_key(3)
