RSA_check_key(3) OpenSSL RSA_check_key(3)
NAME
RSA_check_key  validate private RSA keys
LIBRARY
libcrypto, lcrypto
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 (p1*q1), 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 objectorientation 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
openssl_rsa(3), ERR_get_error(3)
HISTORY
RSA_check_key() appeared in OpenSSL 0.9.4.
1.0.1i 20090720 RSA_check_key(3)
