add quote from did whitepaper

xdi.md

@@ -29,7 +29,28 @@ The XNS Public Trust Organization was founded in July 2000, shortly after Intern
   - Markus Sabadello
 * [XDI Verifiable Claims and Link Contracts](https://github.com/WebOfTrustInfo/rwot4-paris/tree/master/topics-and-advance-readings/xdi-verifiable-claims-link-contracts.md) by Markus Sabadello
 * [First XDI Link Contract between "btcr" DID and "sov" DID](https://github.com/WebOfTrustInfo/rwot5-boston/tree/master/topics-and-advance-readings/first-xdi-link-contract-between-btcr-did-and-sov-did.md) by Markus Sabadello
-
+* [DID Whitepaper](https://github.com/WebOfTrustInfo/rwot2-id2020/blob/master/topics-and-advance-readings/DID-Whitepaper.md)
+  > In April 2015 the XDI.org trustees formed the XDI Registry Working Group (XRWG) to transition XDI registry infrastructure from a centralized model to a new decentralized blockchain-based model.
+  > 
+  > The charter of the XRWG includes the following principles:
+  >
+  > * Maximum interoperability.   
+  > * Minimum viable centralization. 
+  > * Critical infrastructure. The XDI Registry must provide for a high level of reliability, stability, scalability, security, sustainability and other requirements typical of critical internet infrastructure.
+  > * Sovereign identity. The XDI Registry should enable any XDI authority (person or organization) to fully administer its own registry and/or its own entry in an xdi.org-specified registry, without the need to rely on any particular external administrative authority.
+  > * Neutrality. The XDI Registry should be available to all members of the public and should not discriminate against any party that wishes to use it for any lawful purpose.
+  >
+  > [...]
+  >
+  > A DID architecture should focus on the set of components that Mr. Gupta refers to as "the minimum required for people to be able to do business (or other critical functions) together".
+  >
+  >**A Decentralized Identifier (DID) Registry and Discovery Service**
+  >
+  > This "minimum required" is defined by a union of the proposed requirements identified by the W3C Credential Community Group, the XDI.org Registry Working Group, and the Rebooting the Web of Trust group. It consists of three functions that can be addressed by a combination of blockchain and DHT technology:
+  >
+  > * A DID registration function
+  > * A discovery function - enables looking up a registered DID in the blockchain
+  > * A master key recovery function
 
 ## Project Danube [**^**](#contents)