/// <reference types="node" />
/**
 * Provides AES-256-CBC encryption and message authentication. The CBC cipher is
 * used for good platform native compatability.
 *
 * @see https://security.stackexchange.com/a/63134
 * @see https://security.stackexchange.com/a/20493
 *
 * @arg {Buffer} secret - See PrivateKey.getSharedSecret()
 * @arg {Buffer} message - plaintext
 * @arg {Buffer} [IV = randomBytes(16)] - An unpredictable strong random value
 * is required and supplied by default.  Unit tests may provide a static value
 * to achieve predictable results.
 *
 * @throws {Error} IV must be 16 bytes
 */
export declare function checkEncrypt(secret: Buffer, message: Buffer, IV?: Buffer): Buffer;
/**
 *  Provides AES-256-CBC message authentication then decryption.
 *
 *  @arg {Buffer} secret - See PrivateKey.getSharedSecret()
 *  @arg {Buffer} message - ciphertext (from checkEncrypt)
 *
 *  @throws {Error} decrypt failed
 */
export declare function checkDecrypt(secret: Buffer, message: Buffer): Buffer;