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.