/**
 * Encrypts data using the Multilinear Galois Mode (MGM) with Kuznyechik cipher.
 * @param key Encryption key
 * @param data Data to be encrypted and authenticated
 * @param iv Initialization vector
 * @param additionalData Additional data to be authenticated
 */
export declare const encryptMGM: (key: Uint8Array, data: Uint8Array, iv: Uint8Array, additionalData?: Uint8Array) => Uint8Array;
/**
 * Decrypts data using the Multilinear Galois Mode (MGM) with Kuznyechik cipher.
 * @param key Encryption key
 * @param data Data to be decrypted and authenticated
 * @param iv Initialization vector
 * @param additionalData Additional data to be authenticated
 */
export declare const decryptMGM: (key: Uint8Array, data: Uint8Array, iv: Uint8Array, additionalData?: Uint8Array) => Uint8Array;