import type { ChaChaExports } from './types.js';
/**
 * ChaCha20-Poly1305 AEAD encrypt (RFC 8439 §2.8).
 * @param x          ChaCha20 WASM exports
 * @param key        32-byte key
 * @param nonce      12-byte nonce, must be unique per (key, message)
 * @param plaintext  Data to encrypt (must be ≤ WASM CHUNK_SIZE)
 * @param aad        Additional authenticated data
 * @returns          `{ ciphertext, tag }`, tag is 16 bytes
 */
export declare function aeadEncrypt(x: ChaChaExports, key: Uint8Array, nonce: Uint8Array, plaintext: Uint8Array, aad: Uint8Array): {
    ciphertext: Uint8Array;
    tag: Uint8Array;
};
/**
 * ChaCha20-Poly1305 AEAD decrypt with constant-time tag comparison (RFC 8439 §2.8).
 * Throws `AuthenticationError` on tag mismatch; never returns plaintext on failure.
 * @param x           ChaCha20 WASM exports
 * @param key         32-byte key
 * @param nonce       12-byte nonce, must match the value used to encrypt
 * @param ciphertext  Ciphertext bytes (must be ≤ WASM CHUNK_SIZE)
 * @param tag         16-byte Poly1305 tag
 * @param aad         Additional authenticated data
 * @param cipherName  Error label for `AuthenticationError` (default 'chacha20-poly1305')
 * @returns           Plaintext
 */
export declare function aeadDecrypt(x: ChaChaExports, key: Uint8Array, nonce: Uint8Array, ciphertext: Uint8Array, tag: Uint8Array, aad: Uint8Array, cipherName?: string): Uint8Array;
/**
 * Derive a 32-byte HChaCha20 subkey from `key` and the first 16 bytes of `nonce`.
 * Used as the inner key for XChaCha20-Poly1305 (draft-irtf-cfrg-xchacha §2.3).
 * @param x      ChaCha20 WASM exports
 * @param key    32-byte master key
 * @param nonce  24-byte XChaCha20 nonce (only bytes 0-15 are used)
 * @returns      32-byte HChaCha20 subkey
 */
export declare function deriveSubkey(x: ChaChaExports, key: Uint8Array, nonce: Uint8Array): Uint8Array;
/**
 * Build the inner 12-byte ChaCha20 nonce for XChaCha20 from bytes 16-23 of the
 * 24-byte XChaCha nonce (draft-irtf-cfrg-xchacha §2.3).
 * @param nonce  24-byte XChaCha20 nonce
 * @returns      12-byte inner nonce (bytes 0-3 are zero, bytes 4-11 are nonce[16:24])
 */
export declare function innerNonce(nonce: Uint8Array): Uint8Array;
/**
 * XChaCha20-Poly1305 encrypt (draft-irtf-cfrg-xchacha).
 * Derives HChaCha20 subkey from `key` + nonce[0:16], then runs
 * ChaCha20-Poly1305 with a 12-byte inner nonce (nonce[16:24]).
 * @param x          ChaCha20 WASM exports
 * @param key        32-byte key
 * @param nonce      24-byte nonce
 * @param plaintext  Data to encrypt
 * @param aad        Additional authenticated data
 * @returns          Ciphertext || 16-byte Poly1305 tag
 */
export declare function xcEncrypt(x: ChaChaExports, key: Uint8Array, nonce: Uint8Array, plaintext: Uint8Array, aad: Uint8Array): Uint8Array;
/**
 * XChaCha20-Poly1305 decrypt (draft-irtf-cfrg-xchacha).
 * Derives HChaCha20 subkey, verifies the Poly1305 tag, then decrypts.
 * Throws `AuthenticationError` on tag mismatch.
 * @param x           ChaCha20 WASM exports
 * @param key         32-byte key
 * @param nonce       24-byte nonce, must match the value used to encrypt
 * @param ciphertext  Ciphertext || 16-byte tag (combined format from `xcEncrypt`)
 * @param aad         Additional authenticated data
 * @returns           Plaintext
 */
export declare function xcDecrypt(x: ChaChaExports, key: Uint8Array, nonce: Uint8Array, ciphertext: Uint8Array, aad: Uint8Array): Uint8Array;