import type { OtpDigits } from '../types';
/**
 * Perform dynamic truncation on HMAC result according to RFC 4226
 *
 * @param hmacArray - HMAC result as byte array (minimum 20 bytes)
 * @param digits - Number of digits in the final code (6 or 8)
 *
 * @throws ({@link InternalError}) - if HMAC array is too short or digits is invalid
 *
 * @returns Truncated code as string with leading zeros
 */
export declare const dynamicTruncation: (hmacArray: Uint8Array, digits: OtpDigits) => string;