<style> p { text-align: left; } </style> # Credential Types --- ## Basic Cryptography > Warning: Not a deep cryptography discussion **Sign**: Using a private key, create a signature **Verify**: Using the corresponding public key, verify the signature. The signed data cannot be modified without invalidating the signature. --- **Symetric Keys**: one key used for both encryption and decryption, or sign and verify **Asymetric Keys**: two keys (one private, one public) that can be used to encrypto and decrypt, sign and verify Nearly all modern cryptography uses Asymetric Keys --- ## Credential Purpose A *Verifiable Credential* is just some data that has been signed by one party and can be verified by another. Verifiable Credentials make Trust Portable --- # Credential Anatomy - Encoding - Signature Style - Envelope Format --- ## Privacy Preserving Technologies - Selective Disclosure - generally accepted as a useful feature - Predicates - common to claim these are not necessary. I'm writing about this. - Non-correlative holder binding - also missunderstood. I'm gonna write about this too. --- ## AnonCreds - All the privacy features - Flat structure - Requires a Credential Definition - keys for each field - Currently bound to Indy ledgers (active work to relax this constraint) - Data encoded as numbers - Credential as _issued_ different than credential as _presented_. - Can ONLY be presented by the Holder --- ## 'Other' Cred Types - Can be held and 'presented' by anybody - This can be very useful - Data issued is the same as data presented - Presentation by holder must also prove they are the subject - Typically by proving DID ownership --- ## JSON-LD - Deep semantic structures - Data encoded using JSON-LD specific canonicalization - Encoding not specific to JSON, allows for other formats much easier. --- ## JSON-LD BBS+ - BBS+ is a different signature scheme - Allows for selective disclosure - Could _therotically_ provide predicates - Generates the Cred-Def dynamically --- ## JWT - Flat-ish structure - Low semantic meaning - Data encoded using Base64 --- ## ACDCs? - Based in the KERI world - Coming soon? --- ## Links https://www.w3.org/TR/vc-data-model/#types https://anoncreds-wg.github.io/anoncreds-spec/