BitChat encrypts messages based on their context, whether private, group, or broadcast, and automatically splits large messages into 500-byte chunks to ensure efficient delivery over its Bluetooth-only mesh network.

Quotes that support claims

Messages are encrypted based on whether they are private, in a room, or broadcast, and large messages are fragmented into smaller 500-byte chunks.

To maximize the efficiency of transmission over the Bluetooth mesh network, large messages are automatically fragmented into 500-byte messages.