The updated WebCrypto use-cases wiki

http://www.w3.org/2012/webcrypto/wiki/Use_Cases

_Credit card processing

http://www.vpay.co.kr/home/eng/03_support/popup_payment.html
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I think you need more detail on how the various steps (ideally) are dealt with.

_SSL VPN

Most companies use SSL-based VPN with pre-installed agent programs, but the method of authentication is just a PIN code or one-time password. Certificate-based VPN on the Web will be a good market to many security companies and useful to users.

    http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/htwebvpn.html
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What exactly is WebCrypto addressing here?
AFAICT the only unsolved (non-standard at least) issue is certificate enrollment.

Generic: For each use-case there should be a line or two telling in a fairly concrete way what WebCrypto brings to the table.
In particular the encryption examples need more meat since static encryption keys so far have not been a major success and we all know why: Key management is a royal PITA!

_Handling S/MIME mail
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If WebCrypto can make S/MIME encryption work for "humans" then you have done something that I didn't thought even was technically possible :-)

thanx
Anders