This means that you are right. Alas, the decryption key (they symmetric key used to encrypt this particular message) is derived deterministically from the private key and nonce. The nonce they use is the hash of the chunk. Thus, the same chunk will always be encrypted with the same symmetric key.
This means that you are right. Alas, the decryption key (they symmetric key used to encrypt this particular message) is derived deterministically from the private key and nonce. The nonce they use is the hash of the chunk. Thus, the same chunk will always be encrypted with the same symmetric key.