In short, the Crypto Bone is a novel approach to making confidential communication both secure and usable. While you are writing or reading messages on your Linux computer, the security of your communication is always at risk, because malware can affect your computer in many ways. The computer we use day-by-day essentially is too complex and too vulnerable to be completely secure. It is quite obvious that in using a second external device to encrypt your messages, security can be improved considerably. The original idea was to use an autonomous micro computer like the Beagle Bone or the Raspberry Pi to delegate all encryption and key management to a device that can be much more secure than the computer you usually use. Such a secure, external device can help ordinary users to establish secure communication with other people that is always encrypted. And at the same time it will make life easier for people, because all message keys are stored in a safe place. Apart from providing a single secret when a conversation with somebody starts, there is no need to keep track of the message keys used to encrypt the messages that are sent out. These keys are updated and managed automatically in a safe manner, so that the user is not required to remember keys or complex passwords to continue the secure communication. It is your login password that you'll need to run the graphical user interface, because the keys are stored in the memory of a daemon that can only be used with root permissions. Users don't need any knowledge of cryptography or special skills to operate the Crypto Bone. And they still maintain the sole control over the message keys themselves, as it possible to interrupt or reset the initial secret for any communication using the graphical user interface. Although such a separate, external device is quite useful to secure the database in which message keys are stored, it is also possible to use a carfully designed daemon on the main machine to be used as a local, software-based Crypto Bone. Obviously the local Crypto Bone is less secure than an external device, but as a carefully designed daemon process it can protect all message keys against malware threats that don't gain full root privilege on the main machine. The Crypto Bone makes sure that all messages are encrypted with keys stored locally in a safe place, either inside the local cryptobone daemon on your main computer or in a separate external device, if additional protection of the message key database is required. No third party needs to be trusted to make secure confidential communication happen. It's all under the user's control. The system updates the message encryption keys with every message exchange, so that only currently used message keys are in the computer's main memory. Past messages have been read already and their decryption keys are reliably deleted and forgotten. This mechanism ensures that messages exchanged in the past cannot be read, even if the encrypted messages are leaked, because the encryption keys, previously stored in main memory, are long gone and cannot be re-constructed.