Management of signature keys for government

[Nicholas Bohm]

At 09:04 2/03/98 +0000, Ross Anderson wrote:
[snip]
>So if you switched from RSA to DSA and thus had a key generation time
>of 1/2 sec rather than 30 sec, then given a trustworthy terminal in
>the bank the customer can generate an initial signing key which can't
>be reconstructed unless both the bank and VISA cheat. Add tamper
>resistant boxes at both these places, add lots of audit, and ensure
>that if they do cheat they can acquire stupendous liabilities.
>Experience shows that you can just about make this work.

A few years ago I advised one of the Clearing Banks on the terms and
conditions applying to their electronic banking services to corporate
customers.  These terms made the customer responsible for instructions
authenticated with the customer's key, as provided by the bank to the
customer.  I made the point that this term would not work satisfactorily
unless the bank took adequate steps to ensure that the key was in fact
delivered to an individual member of staff who was properly authorised by
the corporate customer to receive it.  I criticised the then current
practice of sending the key by ordinary post to the company in an envelope
addressed impersonally to "the Managing Director".  I was told by the
bank's legal department that this comment was regarded by the bank as
extending beyond the scope of my instructions.

There certainly seem to be a remarkable number of ways for this sort of
thing to go wrong.  I certainly feel more secure with a system where I can
generate my own key pair on my own (non-networked) PC while offline from
the net.  Given the problems which seem (from correspondence in this list)
to arise when trying to be sure of the security of card-based systems, what
is their advantage?

[snip]

	Regards,

		Nicholas Bohm

Salkyns, Great Canfield,
Takeley, Bishop's Stortford CM22 6SX, UK

Phone		01279 870285	(+44 1279 870285)
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PGP RSA 1024 bit public key ID: 0x08340015.  Fingerprint:
9E 15 FB 2A 54 96 24 37  98 A2 E0 D1 34 13 48 07
PGP DSS/DH 1024/3072 public key ID: 0x899DD7FF.  Fingerprint:
5248 1320 B42E 84FC 1E8B  A9E6 0912 AE66 899D D7FF