RE: Cryptographically Enforceable Issuer Policies (forked

Hi Steve,

Before answering your question, let me tell you this is still stuff we are coming to grips with - it is the subject of a masters thesis that Naveena Anaigoundanpudur Karthikeyan is working on with TNO. So what I write below are ideas that I still need to see verified.

We introduce a new role, which we call `KeySmith`, that generates all keys involved. Specifically:

  *   It publishes the public key (and some other stuff) that issuers can use to encrypt credentials under their policy, and
  *   It provides a Decryption-Key Provisioning Service (DKPS) that other parties can supply attributes to and then obtain a decryption key that enables them to decrypt any credential that was encrypted under a policy that is satisfied by the attributes that the party supplied.

Determining whether or not a verifier (or a holder for that matter) can decrypt a credential relies on:

  *   The crypto-magic that is called Ciphertext Policy Attribute Based Encryption (CP-ABE);
  *   The rigor with which the KeySmith validates the attributes that parties supply as they request a decryption key.

Consequently, parties that issue credentials under such a policy must (be able to) determine

  *   That he attributes that a KeySmith uses to generate decryption keys are sufficient for expressing its policy
  *   That the process that the KeySmith uses to validate the attributes that parties provide as they request a decryption key, provides sufficient assurance that the (cryptograhpic) evaluation of the policy is also valid. And I think this is the trickiest part.

Rieks

From: steve.e.magennis@gmail.com <steve.e.magennis@gmail.com>
Sent: donderdag 20 mei 2021 16:17
To: Joosten, H.J.M. (Rieks) <rieks.joosten@tno.nl>; 'Luca Boldrin' <luca.boldrin@infocert.it>; 'Michael Herman (Trusted Digital Web)' <mwherman@parallelspace.net>
Cc: 'public-credentials' <public-credentials@w3.org>; Kruijssen, A. (Age) <age.kruijssen@tno.nl>; Stornebrink, M.H.M. (Michiel) <michiel.stornebrink@tno.nl>
Subject: RE: One subject, 2 VCs, 2 duplicate properties

... forking the conversation r.e. Cryptographically Enforceable Issuer Policies
@Joosten, H.J.M. (Rieks)<mailto:rieks.joosten@tno.nl>, how would it be determined if a Verifier satisfies policy conditions? Really interesting idea.
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