XChaCha20 as defined by the XChaCha20 IRTF CFRG draft.
export const KEY_BYTES: number = 32;
export const NONCE_BYTES: number = 24;
export function xchacha20(
out: Uint8Array,
key: Uint8Array,
nonce: Uint8Array,
counter: number,
text: Uint8Array
): void;xchacha20 does not do any input validation. Make sure key and nonce have correct sizes and that counter is an uint32. Also, guarantee that out.byteLength === text.byteLength.