This Credentica- UProve paper describes how Verisign issues (or did issue in the past) certs with encrypted attributes:

"VeriSign issues certificates that contain encrypted attributes that can be unlocked only by verifiers that meet the qualifications necessary to receive the required decryption key from a trusted third party"

  • Are there any public examples of this being used?

  • What are some use cases that would require this attribute?

  • Is it unreasonable to assume that I could embed similar attributes in my own CA? (MSFT or otherwise)

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    Constructive feedback on the downvote is appreciated. – halfbit Jul 18 '13 at 21:33
  • The SSL Observatory project may help you with this question: eff.org/observatory – buherator Jul 22 '13 at 8:59

This comment seems to talk about an old VeriSign extension called CZAG. It appeared to have been relatively common a dozen years ago, but I am not sure it is still used. Indeed, it seems that the encryption system was extremely sloppy; this article (published at Usenix in 2002) describes the extension, what it contains, and what it leaks through really poor use of cryptography.

Searching the extension OID (2.16.840.1.113733.1.6.3) on Google uncovers some examples of certificates containing that extension, e.g. this one (this is a GitHub URL, I am not sure how long it will be valid).

It seems that the use case for this extension was of the kind "VeriSign wants to make money". The commercial promise was that users, with CZAG-enabled certificates, could register on some Web sites, the site automatically extracting the user's demographics ("Country, Zip, Age and Gender") without requiring the user to enter the information themselves. For some reason, back in these days, people thought that it was cool to have random Web sites automatically access their private information without control. Anyway, it was an opt-out system, so it can be assumed that most users were simply unaware of these shenanigans.

Most of the references to CZAG I find are from before the 2002 article, so my guess is that this extension was discreetly removed from VeriSign's procedures once it was demonstrated how weak the obfuscation was.

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