/**
 * HMAC-SHA-256 → base64url. Used as the tag for signed CSRF tokens and any
 * other MACed value in this package.
 * @param {string | Buffer | Uint8Array} data
 * @param {string | Buffer | Uint8Array} secret
 * @returns {string}
 */
export function hmacBase64Url(data: string | Buffer | Uint8Array, secret: string | Buffer | Uint8Array): string;