RSA_check_key (3)

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NAME

RSA_check_key - validate private RSA keys

SYNOPSIS

 #include <openssl/rsa.h>

 int RSA_check_key(RSA *rsa);

DESCRIPTION

This function validates 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

.

As such, this function can not be used with any arbitrary

key object, even if it is otherwise fit for regular operation. See for more information.

RETURN VALUE

RSA_check_key() returns 1 if rsa is a valid 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 public keys that have only the modulus and public exponent elements populated. It performs integrity checks on all the key material, so the key structure must contain all the private key data too.

Unlike most other

functions, this function does not work transparently with any underlying implementation because it uses the key data in the structure directly. An implementation can override the way key data is stored and handled, and can even provide support for keys - in which case the structure may contain no key data at all! If the in question is only being used for acceleration or analysis purposes, then in all likelihood the key data is complete and untouched, but this can't be assumed in the general case.

BUGS

A method of verifying the key using opaque functions might need to be considered. Right now RSA_check_key() simply uses the structure elements directly, bypassing the 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 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.