From: adacrypt on
For whatever it may be worth to any reader – in security of
information an out-of-office travelling user may be a business person,
a diplomat, military person or whatever but the need in every case is
the same and is twofold i.e. they need a secure communications
facility to email home sensitive information that is accumulating
during a trip and the means of secure storage of sensitive data within
the computer during a trip. That can only be provided by encryption of
the data that they accumulate during a trip. They may wish to secure
the information should their laptop computer or whatever be lost or
stolen, the loss of the computer is the least of their worries in that
event usually.

The ciphers to hand are written in Ada-95 and operate from a stick of
removable memory in a USB port. The compiler is installed within the
computer but the cipher remains on board the pen drive in the USB

I am claiming that an advantage of using a pen drive like this is that
it alone contains the cipher and the thinking is that the compiler
reads and writes to the pen drive only and thus bye-passes the
computer hard-drive proper. A benefit of this is mode of operation is
that the plaintext for encryption does not get into the hard drive and
the danger of leaving residual impressions on the hard drive that may
be recovered as information by cryptanalysts using forensic means is
obviated. (I would welcome any advanced information from more expert
readers on this point – please verify how correct this claim is –
totally, partly ? – I am not a computer scientist and would
appreciate your help)

The characters for encryption are encrypted one at a time either by
being keyed in at the same computer keyboard in real time or by
reading in from an external batch file so that each character over-
writes the previous one in RAM and in the computer CPU and again no
impressions are left inside the computer so that an adversary who
steals the person’s laptop does not get to stealing the sensitive
information being protected.

This crypto scheme type is not peculiar to Ada-95 alone but the only
ciphers to hand at present that can do this are written by me in
Ada-95. - adacrypt