Negotiation Topics

Compatibility Layers

1. DIDComm Service Type
2. Envelope Type ('accept' proposal)
3. Encryption method (in DID Doc?)
4. Content Encoding (JSON/CBOR)
5. Inner message format (expected attributes within content encoding.)
6. DIDComm Protocol Type

Layers 1-5 Must Align to be able to respond with a message for further negotiation leveraging DIDComm Protocols.

Negotiation Options

1. Profile
   • Profile attribute
   • Indicated by service type (bad idea)
2. pre-flight (re-flight?)
   • .well-known
   • Transport message request/failure response
   • attachment on OOB
3. DID Doc Service Block Attributes

Notes

• Any accept string should be a string match, not to be parsed.
• top level content type is not just envelope type

Orthogonal: Implications on routing

Option 1: Recipient is responsible to line up a delivery path compatible with his stated compatibility.

• Simpler for Sender
• May be inflexible

Option 2: Each routing step can declare it's own compatibility

• Complex for sender
• Full flexibility