/**
 * File Integrity — HMAC-SHA256 signing and verification
 *
 * Used to protect local data files (e.g., usage counters) from manual editing.
 * Tampered files are rejected and treated as empty.
 *
 * @since v2.5.2
 */
export interface SignedData<T> {
    data: T;
    hmac: string;
}
/** Sign data with HMAC-SHA256 */
export declare function signData<T>(data: T, key: Buffer): SignedData<T>;
/** Verify HMAC signature and return data if valid, null if tampered */
export declare function verifySignedData<T>(signed: SignedData<T>, key: Buffer): T | null;
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