/**
 * Encode a Uint8Array or string to Base64.
 * Uses TextEncoder + manual base64 to support binary data correctly.
 */
export declare function encodeBase64(data: Uint8Array | string): string;
/**
 * Decode a Base64 string to Uint8Array.
 */
export declare function decodeBase64(data: string): Uint8Array;
/**
 * Encode text using Quoted-Printable (RFC 2045).
 */
export declare function encodeQP(text: string): string;
/**
 * Encode an email header value per RFC 2047.
 * Non-ASCII values become: =?UTF-8?B?<base64>?=
 */
export declare function encodeHeader(value: string): string;
/**
 * Returns true if the string contains non-ASCII characters
 * and therefore requires RFC 2047 encoding in headers.
 */
export declare function needsEncoding(text: string): boolean;
/**
 * Encode bytes to Base64url (RFC 4648 §5) without padding.
 * Used by Web Push (VAPID / RFC 8291) and similar protocols.
 */
export declare function encodeBase64Url(data: Uint8Array | string): string;
/**
 * Decode a Base64url (RFC 4648 §5) string to bytes.
 * Accepts both padded and unpadded input.
 */
export declare function decodeBase64Url(data: string): Uint8Array;
/** Decode bytes to UTF-8 string. */
export declare function decodeUtf8(bytes: Uint8Array): string;
/** Encode string to UTF-8 bytes. */
export declare function encodeUtf8(text: string): Uint8Array;