--- /dev/null
+/**\r
+ * Calculates the byte length of a base64 encoded string.\r
+ * @param {string} string Base64 encoded string\r
+ * @returns {number} Byte length\r
+ */\r
+export function length(string: string): number;\r
+\r
+/**\r
+ * Encodes a buffer to a base64 encoded string.\r
+ * @param {Uint8Array} buffer Source buffer\r
+ * @param {number} start Source start\r
+ * @param {number} end Source end\r
+ * @returns {string} Base64 encoded string\r
+ */\r
+export function encode(buffer: Uint8Array, start: number, end: number): string;\r
+\r
+/**\r
+ * Decodes a base64 encoded string to a buffer.\r
+ * @param {string} string Source string\r
+ * @param {Uint8Array} buffer Destination buffer\r
+ * @param {number} offset Destination offset\r
+ * @returns {number} Number of bytes written\r
+ * @throws {Error} If encoding is invalid\r
+ */\r
+export function decode(string: string, buffer: Uint8Array, offset: number): number;\r
+\r
+/**\r
+ * Tests if the specified string appears to be base64 encoded.\r
+ * @param {string} string String to test\r
+ * @returns {boolean} `true` if it appears to be base64 encoded, otherwise false\r
+ */\r
+export function test(string: string): boolean;\r