export declare function validFlowSignature(raw: Buffer | undefined, signature: string | undefined, secret: string): boolean;
export declare function decryptFlow(body: any, key: string, passphrase?: string): {
    aes: NonSharedBuffer;
    iv: Buffer<ArrayBuffer>;
    data: any;
};
export declare function encryptFlow(data: unknown, aes: Buffer, iv: Buffer): string;