import { HeaderSignature } from './parser';
/**
 * Helper function to construct the basestring and verify the signature of an
 * incoming request
 * @param uri incoming request to verify
 * @param signatureHeader the X-FormSG-Signature header to verify against
 * @returns true if verification succeeds, false otherwise
 * @throws {WebhookAuthenticateError} if given signature header is malformed.
 */
declare const isSignatureHeaderValid: (uri: string, signatureHeader: HeaderSignature, publicKey: string) => boolean;
/**
 * Helper function to verify that the epoch submitted is recent and valid.
 * Prevents against replay attacks. Allows for negative time interval
 * in case of clock drift between Form servers and recipient server.
 * @param epoch The number of milliseconds since 1 Jan 1970 00:00:00 UTC.
 * @param expiry Duration of expiry in milliseconds. The default is 5 minutes.
 * @returns true if the epoch given has exceeded expiry duration calculated from current time.
 */
declare const hasEpochExpired: (epoch: number, expiry?: number) => boolean;
export { isSignatureHeaderValid, hasEpochExpired };