if ( !BN_set_word(bn, (unsigned long)RSA_F4)
|| !(rsa_key = RSA_new())
|| !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
)
if ( !BN_set_word(bn, (unsigned long)RSA_F4)
|| !(rsa_key = RSA_new())
|| !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
)