export interface SessionIdPayload {
    validFrom: number;
    sessionId: number;
    validTo: number;
}
declare const byteBrand: unique symbol;
export type Byte = number & {
    readonly [byteBrand]: void;
};
export declare const toByte: (n: number) => Byte;
export declare class LavvaBluetoothEncryptionHelper {
    /** Parse MAC like "AA:BB:CC:DD:EE:FF" or "AABBCCDDEEFF" into 6 bytes */
    static parseMac(macStr: string): Uint8Array;
    /** Your MAC->key derivation (32 bytes) */
    static calcChacha20Key(macStr: string): Uint8Array;
    /** 12-byte nonce from payload (little-endian uint32 x3) */
    static getNonce({ validFrom, sessionId, validTo }: SessionIdPayload): Uint8Array;
    /**
     * ChaCha20 stream cipher (IETF): XOR plaintext with keystream.
     * Default counter=1 (common when reserving counter=0 for Poly1305 key derivation).
     */
    static chacha20EncryptBytes(key32: Uint8Array, nonce12: Uint8Array, plaintext: Uint8Array, counter?: number): Uint8Array;
    /** Decryption is identical (XOR again) */
    static chacha20DecryptBytes(key32: Uint8Array, nonce12: Uint8Array, ciphertext: Uint8Array, counter?: number): Uint8Array;
    /** Encrypt hex string (bytes in hex) -> ciphertext hex */
    static chacha20EncryptHex(key32: Uint8Array, nonce12: Uint8Array, plaintextHex: string, counter?: number): string;
    /** Decrypt hex string (ciphertext hex) -> plaintext hex */
    static chacha20DecryptHex(key32: Uint8Array, nonce12: Uint8Array, ciphertextHex: string, counter?: number): string;
    private readonly key32;
    constructor(macStr: string);
    encryptHexWithSession(payload: SessionIdPayload, plaintextHex: string, counter?: number): string;
    decryptHexWithSession(payload: SessionIdPayload, ciphertextHex: string, counter?: number): string;
    getKeyBytes(): Uint8Array;
    private static readonly SIGMA;
    private static chacha20Xor;
    /** Write 64-byte keystream block into `out64` */
    private static chacha20Block;
    private static quarterRound;
    private static rotl32;
    private static u8ToU32LE;
    private static u32ToU8LE;
    static bytesToHex(bytes: Uint8Array): string;
    static hexToBytes(hex: string): Uint8Array;
    private static readonly HEX_LUT;
    private static hexNibble;
    static stringToHex(str: string): string;
    static hexToString(hex: string): string;
}
export {};