Telephone spam

By Ashok Argent-Katwala

I've always been quite wary of the Telephone Preference Service (and its sibling the Mail Preference Service). It makes me nervous that the do-not-spam list is held by an organisation that promotes direct marketing.

After getting more marketing calls, and this weekend a spam text message from Firezza (a local pizza firm, no link-love from here), I finally signed up for the TPS for my mobile number and our home number.

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Unfortunately, this showed up a rudimentary security error by the TPS. As is common, they verify the email address you give them by sending a link you must follow before they act on your request.

Alas, the two links they sent me were:

 https://secure.dma.org.uk/tps/confirm/xxxxx28
 and
 https://secure.dma.org.uk/tps/confirm/xxxxx29

(for the same xxxxx in each case).

That is, they're using a serial number as the hard-to-guess, hard-to-forge thing.

I can think of nice, privacy respecting ways to store do-not-spam lists, using something like a Bloom filter. Unfortunately, doing that would require a basic understanding far in excess of the TPS' displayed competence.