RSA_check_key(3)

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 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

1.0.2t               Last change: 2019-09-10                    1

RSA_check_key(3)             OpenSSL             RSA_check_key(3)

     "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.

1.0.2t               Last change: 2019-09-10                    2