


Perhaps the most important advantage of full disc encryption, though - beyond the peace of mind it gives your business's lawyers - is the "safe harbour" immunity that accrues under many data privacy regulations. For example, credit card disclosure rules don't apply to encrypted data, and even California's strict data-disclosure statute makes an exception for encrypted records - provided you can prove they're encrypted. That's trivial with full disc encryption but not so easy with partial encryption techniques, which depend on user education for safe operation.

A key challenge for IT in deploying encryption on its laptops is the sheer number of encryption options available. Some Windows Vista editions, as well as the forthcoming Windows 7, support Microsoft's built-in BitLocker encryption, and numerous third-party encryption products cover the range of mobile operating systems from XP through Windows 7, Linux, and Mac OS X. Encryption granularity is widely variable as well, ranging from protecting individual files to encrypting virtual discs to deploying fully armored, hardware-based full disc encryption. Prices range from free to moderately expensive.
If you've put off laptop data security due to perceived technical shortcomings or high costs, you need to take another look at the field - before you lose another laptop.

Maximum encryption protection possible: TPM

Ideally, you'll deploy the full-metal-jacket approach to laptop data protection: full disc encryption using the Trusted Platform Module (TPM) technology. If you can afford the cost, waste no time with inferior methods. All you need is a laptop containing a TPM security coprocessor and, optionally, an encryption-enabled hard drive from one of the major hard drive manufacturers.

The TPM is a chip soldered on to the laptop's motherboard, providing hardware-based device authentication, tamper detection, and encryption key storage. The TPM generates encryption keys, keeping half of the key information to itself, making it impossible to recover data from an encrypted hard drive apart from the computer in which it was originally installed. Even if an attacker gets the user's part of the encryption key or disc password, the TPM-protected drive's contents can't be read when connected to another computer. Further, the TPM generates a unique digital signature from the motherboard in which it's embedded, foiling attempts to move the TPM chip itself to another machine.

TPM-enabled full disc encryption, especially hardware-based implementations of it, provides one other key benefit to enterprises: data erasure upon laptop decommissioning or repurposing. A common bugaboo in the enterprise is the accidental disclosure of data when seemingly worthless outdated laptops are discarded or sold, or transferred to another employee. Erasing sensitive information in such situations is not trivial, and even removing and physically mangling a laptop's hard drive is no guarantee against disclosure. However, because TPM has absolute control over the encryption keys - remember, half of the key information is stored with the TPM itself - you can simply tell TPM to forget its keys, and the hard drive is instantly reformatted and effectively rendered non-recoverable. disc sectors aren't zeroed, but no computationally feasible method exists today to decrypt the residue.






To achieve the ultimate in full disc encryption protection requires hardware-enabled encryption on board the hard drive. Drive-based encryption closes all of TPM's loopholes, since the encryption key is no longer stored in OS-accessible memory. Hardware-based full disc encryption also eliminates the performance penalty incurred by software-based full disc encryption, although with today's fast, processors, that software encryption overhead is not noticeable to most users.


You can also roll your own software protection using stand-alone packages such as PGP Whole disc Encryption.


If you can't do TPM, here's your plan B for encryption



A variation of folder-level encryption is virtual disc encryption (VDE), in which a single disc file contains a virtual disc image that the user can mount when needed; this virtual disc collects all sensitive files in one location. Microsoft's BitLocker offers this feature in all Vista editions, as well as in Windows Server 2008 and Windows XP. Third-party products such as PGPdisc and even free open source software programs such as TrueCrypt have VDE capabilities. Many of these third-party utilities are easier to use than BitLocker, so they can save you some implementation expense.


But the best plan B to TPM-enabled full disc encryption isn't any of these partial disc methods. The best plan is software-only full disc encryption, in which either the operating system or a third-party program performs the same encryption as with TPM but uses another method to store the encryption keys, such as a thumb drive or a smart card.

The good news is that virtually all-TPM full disc encryption suppliers' offerings, including BitLocker, can operate in this software-only mode, which relies on a removable hardware token so that you can use this approach for your non-TPM devices while having a consistent encryption method to manage across all your laptops.


Still, when TPM-enabled encryption is not an option, pure software full disc encryption can still give you considerable peace of mind, as well as provide the "safe harbour" benefits afforded encrypted systems in data-privacy regulations. Software full disc encryption solutions have also been around long enough that they're available for most mobile computing platforms, including Linux and Mac OS X.

TPM technology changes to come


One potential vulnerability of today's separate TPM chip implementation is that keys must be transported across conductors in the motherboard to the CPU for software-based full disc encryption, or to the hard drive for hardware-based full disc encryption. That could provide an entry point for a hacker. That's why a major vendor trend is to move all TPM-oriented data manipulation on to the CPU chip set in the form of customised silicon. Intel has advertised vPro, part of the upcoming Danbury processor and Eaglelake chip set. This feature will perform all encryption and decryption for SATA and eSATA drives without involving the CPU, OS device drivers, or even the hard drive itself.
