Skip to content

Latest commit

 

History

History
51 lines (39 loc) · 5.23 KB

corda.md

File metadata and controls

51 lines (39 loc) · 5.23 KB
Raw

Data Sharing Protocol Units in Corda Networks

  • RFC: 02-003
  • Authors: Sandeep Nishad, Venkatraman Ramakrishna, Krishnasuri Narayanam, Dhinakaran Vinayagamurthy
  • Status: Proposed
  • Since: 05-Jan-2023

Summary

  • This document specifies the Corda implementation of modules, and application adaptation guidelines, for the data sharing protocol.
  • Within Weaver, the protocol units to request, share, and validte data will be implemented in the Interoperation CorDapp, which is the interoperation module for a Corda-based network.
  • The protocol unit functions are meant to be called only by relay drivers with special RPC user credentials that are recognized by the Corda network at bootstrap.
  • Within Weaver, the SDK will provide user agents (clients) the capability to trigger cross-ledger data sharing operations, fetching remote state using view addresses and using the proof-accompanied view data in a local business workflow by invoking a Interoperation CorDapp workflow in the local network.

Interoperation CorDapp

The following functions should be implemented in the Interoperation CorDapp as workflows:

  • HandleExternalRequest(val query: QueryOuterClass.Query) : FlowLogic<Either<Error, State.View>>(): this FlowLogic takes the Query structure as parameter. This structure contains both a view address and a verification policy. An access control policy corresponding to the view address should be looked up from the ledger and a check should be run against the requestor's identity (certificate) which is also embedded in the Query structure. If the check passes, an appropriate subflow should be invoked to call the appropriate flow (all details embedded in the Query structure). The result is directly embedded in an InteropPayload structure, if confidentiality is not desired (determined by a flag in the Query structure). Otherwise, the result is encrypted using the public key in the requestor's certificate and a serialized form of a ConfidentialPayload structure is embedded in an InteropPayload structure (to be implemented in future). The serialized form of this InteropPayload structure is then signed by the node. The serialized InteropPayload along with the signature is then packaged in the Corda View data structure. The serialized Corda View structure in ByteArray is then encapsulated in the View structure which is then returned from this function.
  • WriteExternalStateInitiator(val viewBase64String: String, val address: String, val viewContentsBase64: Array<String>): FlowLogic<Either<Error, UniqueIdentifier>>(): this FlowLogic takes an serialized View structure in Base64 encoded string and the view address for the view. It must first validate the proof within the view, depending upon the protocol field in meta field of view. viewContentsBase64, an array of serialized ViewContents in Base64 encoded string, will be used if payload is encrypted to verify confidential payloads, which will contain decrypted payloads of each node (to be implemented in future). If the validation is successful, it creates a linear state called ExternalState corresponding to the View data structure. Then it creates a transaction to record this state in the vault. The linearId corresponding to the ExternalState is then returned which can be used by application to get the validated ExternalState.

Corda Interoperation SDK

The Corda Weaver SDK should implement and offer the following function to serve the end-to-end purpose described in the protocol's client API requirements. The given function signature is suggestive and in Kotlin syntax, but it can be modified or adapted as per need.

fun interopFlow (
    proxy: CordaRPCOps,
    localRelayEndpoint: String,
    externalStateAddress: String,
    networkName: String,
    confidential: Boolean = false,
    useTlsForRelay: Boolean = false,
    relayTlsTrustStorePath: String = "",
    relayTlsTrustStorePassword: String = "",
    tlsCACertPathsForRelay: String = ""
): Either<Error, String>

Some of the parameters are defined below:

  • proxy: instance of CordaRPCOps, a connection to a Corda node using RPC credentials of the user who submitted the query, indicating which node to submit the remote data to.
  • localRelayEndpoint: the local relay endpoint address of form <HOSTNAME/IP>:<PORT>.
  • externalStateAddress: View Address for the data sharing query.
  • confidential: if this is set to true, the contents embedded within the returned views are expected to be encrypted using the public key embedded within the keyCert parameter (to be implemented in future).

This returns the linearId of the ExternalState if the complete protocol is successful, else return an error.