/**
 * One strict base64 decoder shared by every caller (writeBinary, S3 binary
 * uploads). A lenient decoder silently drops invalid characters and
 * truncates at bad padding, so it would produce corrupted bytes rather than
 * fail. This validates first and throws a clear error; whitespace is allowed
 * and ignored. The decoding itself is the platform's own `atob`, which Node
 * and browsers both have.
 */
export declare const BASE64_QUANTUM_LENGTH = 4;
export declare const BASE64_MAX_PADDING_LENGTH = 2;
export declare const BASE64_ALPHABET_AND_PADDING: RegExp;
export declare function decodeBase64Strict(base64: string): Uint8Array;
/** `encodeBase64` in the URL-safe alphabet with no padding, the way
 *  `base64url` spells it. */
export declare function encodeBase64Url(bytes: Uint8Array): string;
/** The number of bytes in the UTF-8 encoding of `text`. */
export declare function utf8ByteLength(text: string): number;
/** Standard base64 with padding, through the platform's own `btoa`, which
 *  Node and browsers both have. `btoa` takes a string of byte values. */
export declare function encodeBase64(bytes: Uint8Array): string;
/** `encodeBase64` of the UTF-8 bytes of `text`. */
export declare function encodeBase64Text(text: string): string;