sometimes,we read DER-encoded RSA public key from memory but not file,so I suggest RSAKeyImpl.h add a constructor ,it use
RSA * d2i_RSAPublicKey(RSA **a, const unsigned char **pp, long length);
RSA * d2i_RSAPrivateKey(RSA **a, const unsigned char **pp, long length);
to get the public key and private key.
other info:
http://www.openssl.org/docs/crypto/d2i_RSAPublicKey.html
