PGP disk encrypt approved by MoD for military use
The British protective markings run from UNCLAS (Impact Level 1-2) to RESTRICTED (Impact Level 3) through CONFIDENTIAL (4), SECRET (5) and TOP SECRET (6).
There are some security products already on the UK market certified to higher levels, for instance Flagstone Enhanced rated for TOP SECRET information - but this requires replacement of a laptop's hard disk with special hardware, which would be overkill for most users. Microsoft's BitLocker, included in some versions of its later operating systems, is (like PGP) only OK'd for RESTRICTED.
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