package tezos-crypto

secretbox key msg nonce encrypts and authenticates the data in msg using key and nonce and returns the authentication tag and the ciphertext in one buffer. For this reason, the returned buffer will be tag_length longer than msg.

secretbox_open key cmsg nonce verifies and decrypts cmsg using key and nonce and returns the plaintext if successful. As above, the returned buffer will be tag_length shorter than cmsg.