/**
 * Decodes the base64 encoded string into a `string`.
 * @hidden
 * @param {string} input
 * @returns {string}
 */
export declare function base64Decode(input: string): string;
/**
 * Encodes the `input` string into a base64 `string`.
 * @hidden
 * @param {string} input
 * @returns {string}
 */
export declare function base64Encode(input: string): string;
/**
 * Converts regular base64 encoded string to URL-safe base64 encoded string.
 * @hidden
 * @param {string} input - Regular base64 encoded string.
 * @returns {string} - URL-safe base64 encoded string.
 */
export declare function base64UrlFromBase64(input: string): string;
/**
 * Converts URL-safe base64 encoded string to regular base64 encoded string.
 * @hidden
 * @param {string} input - URL-safe base64 encoded string.
 * @returns {string} - Regular base64 encoded string.
 */
export declare function base64UrlToBase64(input: string): string;
/**
 * * Encodes the `input` string into a string using URL-safe base64 encoding.
 *
 * @hidden
 *
 * @param {string} input - The input.
 * @returns {string}
 */
export declare function base64UrlEncode(input: string): string;
/**
 * Decodes the URL-safe base64-encoded `input` string into a `string`.
 *
 * @hidden
 *
 * @param {string} input
 * @returns {string}
 */
export declare function base64UrlDecode(input: string): string;