I have written before about the "Verified by VISA" program. While shopping for Thanksgiving online this year, I noticed that Verified by Visa scripts were blocked by NoScript, and I could complete my purchases without authenticating. It was tempting to conclude that the implementation was faulty, but a few phone calls clarified that the Purdue Employee Federal Credit Union stopped participating in the program. I have ambivalent feelings about this. I'm glad that PEFCU let us escape from the current implementation and surprise enrollment based on SSN at the time of purchase, and SSN-based password reset. Yet, I wish a password-protection system was in place because it could significantly improve security (see below). Getting such a system to work is difficult, because in addition to needing to enroll customers, both banks and merchants have to support it. For the sake of curiosity, I counted the number of participating stores in various countries, as listed on the relevant VISA web sites:

Country	Number of Stores
USA	126
Europe	183
Thailand	439
Taiwan	144
Japan	105
China	90
Singapore	65
Malaysia	27
Hong Kong	20
Vietnam	17
Australia	13
India	7
Others	0

Multiply this by the fraction of participating banks (data not available for the US), and for a program that started in 2001, that's spotty coverage. Adoption would be better by getting people to enroll when applying for credit cards, when making a payment, by mail at any time, or in person at their bank. The more people adopt it, the more stores and banks will be keen on reducing their risk as the cost per participating card holder would decrease. Ambushing people at the time of an online purchase with an SSN request violates the security principle of psychological acceptability. The online password reset based on entering your SSN, which I had criticized, is still exposing people to SSN-guessing risks, and also the only means to change your password. I wish that VISA would overhaul the implementation and use an acceptable process (e.g., a nonce-protected link via email to a page with a security question). The reason I'm interested is because I'd rather have a password-protected credit card, and a single password to manage, than a hundred+ online shopping accounts that keep my credit card information with varying degrees of (in)security. Using an appropriate choke-point would reduce attack surface, memorization requirements, and identity theft.