OMAP3530 Securing Read Access to NAND flash memory

Hi There,

We are developing a data-logging application based around an omap 3530 running OpenEmbedded linux. The units will use a dial-home function using a gsm modem and will utilise a VPN to secure the connection. As such, there will be files containing passwords to allow this secure connection to establish. The OS will be installed into the NAND flash, with the boot order set to NAND flash only, with no secondary devices.

The devices will be installed in the open, where we don't have physical security over the device. Our concern is that a would be attacker could access the device, and find the connection settings for the VPN and thus gain access to the home network. Whilst this might seem paranoid, for this particular application, its important to cover these bases to satisfy the IT chiefs.

So my question is, with an OS installed in the NAND flash, how can we protect the flash from being read when the OS is not booted? We assume that the attacker has access to all ports such as JTAG, etc. We would still need read/write access from the OS to the flash.

Thanks for any help you can give,
Regards
Rob Smith