[149154] in cryptography@c2.net mail archive
Re: [Cryptography] one-time pads
daemon@ATHENA.MIT.EDU (Philip Shaw)
Tue Jan 21 02:48:13 2014
X-Original-To: cryptography@metzdowd.com
From: Philip Shaw <wahspilihp@gmail.com>
In-Reply-To: <CAAMy4URooutxtYX4WNEVkqhSCR867pod2OJec-FyW5xACBQasQ@mail.gmail.com>
Date: Tue, 21 Jan 2014 13:12:29 +1030
To: Tom Mitchell <mitch@niftyegg.com>
Cc: John Kelsey <crypto.jmk@gmail.com>,
"cryptography@metzdowd.com" <cryptography@metzdowd.com>,
Bill Frantz <frantz@pwpconsult.com>
Errors-To: cryptography-bounces+crypto.discuss=bloom-picayune.mit.edu@metzdowd.com
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On 21 Jan 2014, at 5:11 , Tom Mitchell <mitch@niftyegg.com> wrote:
> The top to bottom structure of the pad makes them a stream cypher =
although a
> key in the corner can ID any page so pages can be tossed if the =
protocol is to
> attach the page key i.e. not "Page 1, 2, 3,.." but a fixed length
> field "(C}TEw[;wgU5*2c"
> messages can be sent out of sequence but that implies the pad is =
busted open
> commonly undesirable with a OTP (at both ends). Page key tricks are =
possible.
>=20
> After folk address my naive summary above, what does a modern OTP look =
like?
ISTR reading something about using data tape with a modified reader, so =
that the tape is erased after it passes through the read head, then =
over-written multiple times (and then burnt - the overwriting is just to =
protect against the tapes being intercepted on their way to the =
incinerator).
Of course, that makes the reader totally obvious to anyone who looked, =
but IIRC the device was for use inside embassies or similar facilities, =
so the pads could be transported by diplomatic courier anyway.
I have had the idea of producing something compatible with an SD reader =
(at least the common open-ended type) but which stores the data embedded =
inside cardboard or similar material, which can be doped on the outer =
end with the phosphorous + shielding layer used on strike-anywhere =
matches, but I haven=92t worked out any specifics, and it would probably =
only be practical to store a KB at most - so useful for a couple of =
private keys but not much else. It still wouldn=92t be deniable, but it =
would be trivial to destroy in a hurry.
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