/**
 * Minimum length required of a cookie-signing secret.
 *
 * Cookie signatures use HMAC-SHA256; a weak or empty secret makes the signature trivially
 * forgeable. 32 characters (~256 bits when random) is the floor for a usable secret. A shorter
 * or empty secret is rejected loudly rather than silently producing a forgeable signature.
 */
export declare const MIN_COOKIE_SECRET_LENGTH = 32;
/**
 * Whether a secret is strong enough to sign/verify cookies.
 *
 * @param secret - The candidate secret.
 * @returns True when the secret is a string of at least {@link MIN_COOKIE_SECRET_LENGTH} chars.
 */
export declare const isSignableCookieSecret: (secret: unknown) => secret is string;
/**
 * Check if the value is serialized.
 * @param value - The value to check.
 */
export declare const isCookieValueSerialized: (value: unknown) => value is string;
/**
 * Check if the value is signed.
 * @param value - The value to check.
 */
export declare const isCookieValueSigned: (value: unknown) => boolean;
/**
 * Sign the cookie value.
 *
 * @param value - The value to sign.
 * @param secret - Secret for signing (must be strong, see {@link isSignableCookieSecret}).
 * @throws {CookieError} If the value is not a string, is already signed, or the secret is weak/empty.
 */
export declare const signCookieValue: (value: unknown, secret: string) => string;
/**
 * Unsign the cookie value.
 *
 * @param value - The signed value.
 * @param secret - Secret for unsigning (must be strong, see {@link isSignableCookieSecret}).
 * @throws {CookieError} If the value is not a signed string or the secret is weak/empty.
 */
export declare const unsignCookieValue: (value: unknown, secret: string) => string | false;