export declare class Base64Encode {
    /**
     * Returns URL Safe base64 encoded string from a plaintext string.
     */
    static urlEncode(input: string): string;
    /**
     * Returns URL Safe base64 encoded string from an int8Array.
     */
    static urlEncodeArr(inputArr: Uint8Array): string;
    /**
     * Returns base64 encoded string from plaintext string.
     */
    static encode(input: string): string;
    /**
     * Base64 encode byte array
     */
    private static base64EncArr;
    /**
     * Base64 string to array encoding helper
     */
    private static uint6ToB64;
}