XORs data with the ChaCha20 keystream for key (32 bytes) and nonce
(12 bytes), starting at block counter. Applying it twice restores the
input. There is no bc-crypto function for this; it is provenance-mark's
ChaCha20::new + apply_keystream (the chacha20 crate).
InvalidParameter on a non-Uint8Array argument or
a non-object options; InvalidSize on a wrong-length key or nonce;
InvalidParameter if counter is outside [0, 2^32 - 2] or the data
would use the backend-reserved block counter 2^32 - 1.
XORs
datawith the ChaCha20 keystream forkey(32 bytes) andnonce(12 bytes), starting at blockcounter. Applying it twice restores the input. There is nobc-cryptofunction for this; it is provenance-mark'sChaCha20::new+apply_keystream(thechacha20crate).