export default class Webhooks {
    publicKey: string;
    secretKey?: string;
    constructor({ publicKey, secretKey, }: {
        publicKey: string;
        secretKey?: string;
    });
    /**
     * Injects the webhook public key for authentication
     * @param header X-FormSG-Signature header
     * @param uri The endpoint that FormSG is POSTing to
     * @returns true if the header is verified
     * @throws {WebhookAuthenticateError} If the signature or uri cannot be verified
     */
    authenticate: (header: string, uri: string) => boolean;
    /**
     * Generates a signature based on the URI, submission ID and epoch timestamp.
     * @param params The parameters needed to generate the signature
     * @param params.uri Full URL of the request
     * @param params.submissionId Submission Mongo ObjectId saved to the database
     * @param params.epoch Number of milliseconds since Jan 1, 1970
     * @returns the generated signature
     * @throws {MissingSecretKeyError} if a secret key is not provided when instantiating this class
     * @throws {TypeError} if any parameters are undefined
     */
    generateSignature: ({ uri, submissionId, formId, epoch, }: {
        uri: string;
        submissionId: string;
        formId: string;
        epoch: number;
    }) => string;
    /**
     * Constructs the `X-FormSG-Signature` header
     * @param params The parameters needed to construct the header
     * @param params.epoch Epoch timestamp
     * @param params.submissionId Mongo ObjectId
     * @param params.formId Mongo ObjectId
     * @param params.signature A signature generated by the generateSignature() function
     * @returns The `X-FormSG-Signature` header
     * @throws {Error} if a secret key is not provided when instantiating this class
     */
    constructHeader: ({ epoch, submissionId, formId, signature, }: {
        epoch: number;
        submissionId: string;
        formId: string;
        signature: string;
    }) => string;
}