http://74f5ydnjsrizxzjux3ivt5qt2epgzvq2pfipttdpjblyqcx7i4sq.b32.i2p/chat98/chat98/commit/358aa6038cb79ae451a8d6d1fae44ba32ac77741.diff
It is the actual message, end-to-end encrypted using the recipient's public key (the key shared with others to add as buddies), and your secret key. These keys are X25519 keys, and the encryption algorithm used for this layer is **AES/CBC/PKCS5Padding**.