This check-in adds three additional functions for backwards compatibility: crypto_box_unchecked, crypto_box_open_unchecked and crypto_box_beforenm_unchecked. The functions can be used for interoperability with downlevel clients, like old versions of NaCl and libsodium. It should also help some cryptocurrencies, like Bitcoin, Ethereum, Monero and Zcash.
Also see https://eprint.iacr.org/2017/806.pdf (low order element attack) and https://github.com/jedisct1/libsodium/issues/662 (Zcash break).