So the user holds the secret key (a good password in their mind) which is used to decrypt the whole system? Would it not be possible to implement some form of full disk encryption on the SD card in a way that it prompts the user for a decryption key on-boot. I'm confused by the negative responses on this, as though it is impossible to encrypt a device. If I were your client, you'd be sacked by now. (d) You have not thought of this yourself. (c) google it - the first 2 links I got told me all I needed to know. (b) It will be slower than it already is. This may or may not be acceptable to you or your client. (a) You/Someone will need to provide the password at boot time every time the Pi is booted. You can even do this on an already setup Pi. You can also encrypt the whole / partition (but not the /boot partition). Then you put all your applications and data in this partition with the rest of the usual/generic Raspbian in the first partition, as normal. You could re-partition the SD card and create a new empty, encrypted partition. This is my costumer requirement, please any one help me on this. In sdcard loads my application code, if any other persons open sdcard he will not understand my code. What is the best method to provide security to my device,am disabling ssh,root access etc, but i need sdcard security also,
