pub unsafe extern "C" fn botan_privkey_export_encrypted_pbkdf_iter(
    key: botan_privkey_t,
    out: *mut u8,
    out_len: *mut usize,
    rng: botan_rng_t,
    passphrase: *const c_char,
    pbkdf_iterations: usize,
    cipher_algo: *const c_char,
    pbkdf_algo: *const c_char,
    flags: u32
) -> c_int