NAME    [Toc]    [Back]

       RSA_check_key - validate private RSA keys

SYNOPSIS    [Toc]    [Back]

        #include <openssl/rsa.h>

        int RSA_check_key(RSA *rsa);

DESCRIPTION    [Toc]    [Back]

       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    [Toc]    [Back]

       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    [Toc]    [Back]

       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    [Toc]    [Back]

       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    [Toc]    [Back]

       rsa(3), ERR_get_error(3)

HISTORY    [Toc]    [Back]

       RSA_check_key() appeared in OpenSSL 0.9.4.


OpenBSD 3.6                 2002-09-10                          2