/**
 * Encrypts data using the Counter (CTR) mode with Kuznyechik cipher.
 *
 * @param key Encryption key
 * @param data Data to be encrypted
 * @param iv Initialization vector
 * @returns {Uint8Array}
 */
export declare const encryptCTR: (key: Uint8Array, data: Uint8Array, iv: Uint8Array) => Uint8Array;
/**
 * Decrypts data using the Counter (CTR) mode with Kuznyechik cipher.
 *
 * @param key Encryption key
 * @param data Data to be decrypted
 * @param iv Initialization vector
 * @returns {Uint8Array}
 */
export declare const decryptCTR: (key: Uint8Array, data: Uint8Array, iv: Uint8Array) => Uint8Array;