x5: Add req and provide skeleton

x5.md

@@ -8,6 +8,47 @@ created: 2019-04-18
 updated:
 ---
 
+# Introduction
+
+## Requirement
+
+TODO: Fill out and requirement such as cryptographic primitives for key generation, possibly secure vault storage.
+
+## Design goals
+
+TODO: Something briefly on adversary model, i.e. https://code.briarproject.org/briar/briar-spec/blob/master/protocols/BQP.md
+
+TODO: Elaborate on section of requirements below
+Security properties
+
+Network MitM Prevented
+Operator MitM Prevented
+Operator MitM Detected
+Operator Accountability
+Key Revocation Possible
+Privacy Preserving
+Usability
+
+Automatic Key Initialization
+Low Key Maintenance
+Easy Key Discovery
+Easy Key Recovery
+In-Band
+No Shared Secrets
+Alert-less Key Renewal
+Immediate Enrollment
+Inattentive User Resistant
+Adoptability
+
+Multiple Key Support
+No Service Provider
+No Auditing Required
+No Name Squatting
+Asynchronous
+Scalable
+
+NOTE: Several of these we don't do, and e.g. ENS/mutlikey stuff can be noted as future enhancement
+
 ## Trust establishment
 
 Trust establishment deals with users verifying they are communicating with who they think they are. In this document we specify how trust is established in Status, and what guarantees we make and don't make.
@@ -172,4 +213,4 @@ Yes.
 #### Scalable (YES)
 > Trust establishment is efficient, with resource requirements growing logarithmically (or smaller) with the the total number of participants in the system
 
-Yes.
+Yes.