-----BEGIN PGP SIGNED MESSAGE----- Hal Finney writes:

The simple blinded signature model provides a pretty simple way to allow only one pseudonym per True Name in a given forum, if you assume there is some way to distinguish people in the real world. Suppose Cypherwonks wanted only one person per nym. And suppose there was an agency which was able to distinguish people, that is, it could tell when it had seen the same person twice. Now, Cypherwonks asks this agency to give a single blinded signature of a type (exponent) which is unique to that list, to anyone who wants it, but such that nobody gets more than one.

To be accepted on the Cypherwonks list, then, somebody would have to show a signature of this particular type, different from everyone else's. Each person could only get one such token, which Chaum has called an is-a-person credential (again, this is a simplification of his idea, I think).

Real-world application of this protocol still depends on folks not using the credentials of friends/family/dead people, especially where "real name" <-> credential mapping isn't available. -----BEGIN PGP SIGNATURE----- Version: 2.3a iQCVAgUBLaT/gH3YhjZY3fMNAQFIjwQArXybGzGZnHUugI6mcOn8CwhamKC9KxK7 LmWo0lzEsrK8Iq4n17JB9fLKb8Cb3UYYinvBk1Fadr9OcAOANC1bqjDoJ3Dsvyz3 9/AFY8CfiaH9JqhRK1jAMdg2kuAFdtFBENhhXE9f6v6sedeQvclfwea1u5vMaErJ 0aq5KRAQKH4= =MFNH -----END PGP SIGNATURE-----