/**
 * @file protocol.ts
 * @description DTLS 1.2 wire-format constants and TLV/vector encoders.
 * @module dtls/protocol
 *
 * Covers exactly what WebRTC's data channel needs:
 *   cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (0xC02B)
 *   curve secp256r1, signature scheme ecdsa_secp256r1_sha256.
 *
 * References: RFC 6347 (DTLS 1.2), RFC 5246 (TLS 1.2), RFC 8422 (ECC).
 */
export declare const DTLS_1_2 = 65277;
export declare const CONTENT_TYPE: Readonly<{
    CHANGE_CIPHER_SPEC: 20;
    ALERT: 21;
    HANDSHAKE: 22;
    APPLICATION_DATA: 23;
}>;
export declare const HANDSHAKE_TYPE: Readonly<{
    HELLO_REQUEST: 0;
    CLIENT_HELLO: 1;
    SERVER_HELLO: 2;
    HELLO_VERIFY_REQUEST: 3;
    CERTIFICATE: 11;
    SERVER_KEY_EXCHANGE: 12;
    CERTIFICATE_REQUEST: 13;
    SERVER_HELLO_DONE: 14;
    CERTIFICATE_VERIFY: 15;
    CLIENT_KEY_EXCHANGE: 16;
    FINISHED: 20;
}>;
export declare const ALERT_LEVEL: Readonly<{
    WARNING: 1;
    FATAL: 2;
}>;
export declare const ALERT_DESC: Readonly<{
    CLOSE_NOTIFY: 0;
    HANDSHAKE_FAILURE: 40;
    BAD_CERTIFICATE: 42;
    DECRYPT_ERROR: 51;
    INTERNAL_ERROR: 80;
}>;
export declare const CIPHER_SUITE = 49195;
export declare const NAMED_GROUP: Readonly<{
    secp256r1: 23;
}>;
export declare const EC_POINT_FORMAT: Readonly<{
    uncompressed: 0;
}>;
export declare const HASH_ALG: Readonly<{
    sha256: 4;
    sha384: 5;
    sha512: 6;
}>;
export declare const SIG_ALG: Readonly<{
    rsa: 1;
    ecdsa: 3;
}>;
export declare const CERT_TYPE: Readonly<{
    ecdsa_sign: 64;
    rsa_sign: 1;
}>;
export declare const EXTENSION: Readonly<{
    SUPPORTED_GROUPS: 10;
    EC_POINT_FORMATS: 11;
    SIGNATURE_ALGORITHMS: 13;
    EXTENDED_MASTER_SECRET: 23;
    RENEGOTIATION_INFO: 65281;
}>;
export declare const FINISHED_LABEL: Readonly<{
    CLIENT: "client finished";
    SERVER: "server finished";
}>;
/** A parsed DTLS record from {@link parseRecords}. */
export interface Record {
    type: number;
    version: number;
    epoch: number;
    seq: number;
    fragment: Buffer;
}
/** A parsed handshake message header from {@link parseHandshake}. */
export interface Handshake {
    msgType: number;
    length: number;
    messageSeq: number;
    fragmentOffset: number;
    fragmentLength: number;
    body: Buffer;
}
/** Encode a uint24 (3 bytes, big-endian). */
export declare function uint24(n: number): Buffer;
/** Read a uint24 at offset. */
export declare function readUint24(buf: Buffer, off: number): number;
/** Length-prefixed vector with a 1-byte length. */
export declare function vec8(body: Buffer): Buffer;
/** Length-prefixed vector with a 2-byte length. */
export declare function vec16(body: Buffer): Buffer;
/** Length-prefixed vector with a 3-byte length. */
export declare function vec24(body: Buffer): Buffer;
/**
 * Encode a DTLS record (13-byte header + fragment).
 * @param type - CONTENT_TYPE
 * @param epoch
 * @param seq - 48-bit sequence number
 * @param fragment
 * @param version
 */
export declare function encodeRecord(type: number, epoch: number, seq: number, fragment: Buffer, version?: number): Buffer;
/**
 * Parse one or more DTLS records from a datagram. Multiple records may be
 * packed into a single UDP packet.
 * @param packet
 */
export declare function parseRecords(packet: Buffer): Record[];
/**
 * Encode a DTLS handshake message header + body (unfragmented).
 * @param msgType - HANDSHAKE_TYPE
 * @param messageSeq
 * @param body
 */
export declare function encodeHandshake(msgType: number, messageSeq: number, body: Buffer): Buffer;
/**
 * Parse a handshake message header.
 * @param buf - starts at the handshake header
 */
export declare function parseHandshake(buf: Buffer): Handshake;