/**
 * Verify a base64-encoded (or base64url-encoded) signed token against a secret.
 *
 * Returns false if the token format is invalid or the signature does not match.
 *
 * Returns the token without its signature otherwise.
 *
 * @export
 * @param {string} signedToken - The signed token
 * @param {string} secret - The base64-encoded secret with which the token is supposed to have been signed with.
 * @returns {(string|false)} - False or the unsigned token.
 */
export declare function verifySignedToken(signedToken: string, secret: string): string | false;