/**
 * A four way client-server handshake, as excellently described in
 * https://ssbc.github.io/scuttlebutt-protocol-guide/ with a few additions:
 *
 * This protocols has one added version byte, one added difficulty byte, 4 byte added nonce bytes,
 * and a 6 byte added clock timestamp and added optional client/server data exchange for
 * swapping application parameters of default maximum 2048 bytes.
 *
 * The added difficulty byte can be used to force the client to calculate a nonce to match the
 * difficulty level set by the server for the handshake to complete.
 */
/// <reference types="node" />
import { ClientInterface } from "pocket-sockets";
import { HandshakeResult } from "./types";
export declare function writeUInt64BE(target: Buffer, nr: bigint): void;
export declare function readUInt64BE(source: Buffer): bigint;
/**
 * On successful handshake return a populated HandshakeResult object.
 * On unsuccessful throw exception.
 * @return Promise <HandshakeResult>
 * @throws
 */
export declare function HandshakeAsClient(client: ClientInterface, clientLongtermSk: Buffer, clientLongtermPk: Buffer, serverLongtermPk: Buffer, discriminator: Buffer, clientData?: Buffer, clock?: number, maxServerDataSize?: number, timeout?: number): Promise<HandshakeResult>;
/**
 * On successful handshake return a populated HandshakeResult object.
 *
 * On failed handshake throw exception.
 *
 * @param client to send and retrieve data on
 * @param serverLongtermSk this side's long term secret key
 * @param serverLongtermPk this side's long term public key
 * @param discriminator arbitrary data that must exactly match the client discriminator data
 * @param allowedClientKeys if Buffer array it contains all client public keys allowed to handshake.
 *  If a function the function has to return true for the client to be allowed.
 *  If undefined then allow all clients to handshake.
 * @param serverData optional data to pass to the client upon successful handshake. Its length cannot
 *  exceed the client's maximum allowed length.
 * @param clock timestamp in milliseconds for when starting the handshake
 *  This value will be adjusted upwards to be as near as possible for when the clock was sent
 * @param difficulty is the number of nibbles the client is required to calculate to mitigate ddos
 *  attacks. Difficulty 6 is a lot. 8 is max.
 *  If the client does not provide a requested nonce then the handshake is aborted after the clients
 *  second message is retrieved.
 * @param maxClientDataSize the maximum length allowed for the client to pass its optional data.
 * @param timeout in milliseconds to wait for each message before aborting.
 * @return Promise<HandshakeResult>
 * @throws on error
 */
export declare function HandshakeAsServer(client: ClientInterface, serverLongtermSk: Buffer, serverLongtermPk: Buffer, discriminator: Buffer, allowedClientKeys?: ((clientLongtermPk: Buffer) => boolean) | Buffer[], serverData?: Buffer, clock?: number, difficulty?: number, maxClientDataSize?: number, timeout?: number): Promise<HandshakeResult>;