import { HEX_ENC, type UTF8_ENC } from "../constants.js";
/**
 * Encodes a UTF-8 string into bytes.
 * @param str Input string.
 * @returns UTF-8 encoded bytes.
 */
export declare function utf8ToBuffer(str: string): Uint8Array;
/**
 * Decodes UTF-8 bytes into a string.
 * @param buf UTF-8 encoded bytes.
 * @returns Decoded string.
 */
export declare function bufferToUtf8(buf: Uint8Array): string;
/**
 * Concatenates multiple byte arrays.
 * @param buffers Byte arrays to concatenate.
 * @returns Concatenated byte array.
 */
export declare function concatBuffers(...buffers: Uint8Array[]): Uint8Array;
/**
 * Converts bytes to a lowercase hex string.
 * @param buf Input bytes.
 * @param enc Output encoding selector. Only `hex` is accepted.
 * @returns Hex string.
 */
export declare function bufferToHex(buf: Uint8Array, enc?: typeof HEX_ENC | typeof UTF8_ENC): string;
/**
 * Converts a hex string to bytes.
 * @param hex Input hex string, with optional `0x` prefix.
 * @returns Decoded bytes.
 */
export declare function hexToBuffer(hex: string): Uint8Array;
/**
 * Removes a leading `0x` prefix from a hex string.
 * @param hex Input hex string.
 * @returns Hex string without prefix.
 */
export declare function sanitizeHex(hex: string): string;
/**
 * Removes leading zeros from a hex string.
 * @param hex Input hex string.
 * @returns Hex string without leading zeros.
 */
export declare function removeHexLeadingZeros(hex: string): string;
/**
 * Parses a hex string into a number.
 * @param hex Input hex string.
 * @returns Parsed number.
 */
export declare function hexToNumber(hex: string): number;
/**
 * RFC 4648 Base64 from bytes. Chunks `btoa` input to avoid huge spread argument lists.
 *
 * @param buf Input bytes.
 * @returns Base64 string (no line breaks).
 */
export declare function bufferToBase64(buf: Uint8Array): string;
/**
 * RFC 4648 Base64 to bytes (whitespace stripped). Uses `atob`.
 *
 * @param str Base64 string.
 * @returns New `Uint8Array`.
 * @throws {DOMException} Invalid Base64 where `atob` throws.
 */
export declare function base64ToBuffer(str: string): Uint8Array;
/**
 * RFC 4648 Base64url without `=` padding (`-`/`_`). Common for JWK `k`.
 *
 * @param buf Input bytes.
 * @returns Base64url string.
 */
export declare function bufferToBase64Url(buf: Uint8Array): string;
/**
 * Base64url to bytes (optional padding; then {@link base64ToBuffer}).
 *
 * @param str Base64url string.
 * @returns New `Uint8Array`.
 * @throws {Error} Length mod 4 === 1 (invalid).
 */
export declare function base64UrlToBuffer(str: string): Uint8Array;
/**
 * 16-byte AES-128 raw key from `utf8ToBuffer(key.padEnd(16, " "))`. Must yield exactly 16 UTF-8 bytes
 * (same constraint as Web Crypto `importKey("raw", …)` for AES-128).
 *
 * @param key Passphrase.
 * @returns 16 key bytes.
 * @throws {Error} UTF-8 length ≠ 16 after padding.
 */
export declare function aes128StringKeyMaterial(key: string): Uint8Array;
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