ICS 28 CCV draft w/ init and validator set update

README.md

@@ -70,5 +70,6 @@ All standards at or past the "Draft" stage are listed here in order of their ICS
 | -------------------------------------------------------- | ----------------------- | ----- |
 | [20](spec/app/ics-020-fungible-token-transfer/README.md) | Fungible Token Transfer | Candidate |
 | [27](spec/app/ics-027-interchain-accounts/README.md)     | Interchain Accounts     | Draft |
+| [28](spec/app/ics-028-cross-chain-validation/README.md)  | Cross-Chain Validation  | Draft |
 | [29](spec/app/ics-029-fee-payment) | General Relayer Incentivisation Mechanism | Candidate |
 | [30](spec/app/ics-030-middleware) | IBC Application Middleware | Candidate |

spec/app/ics-028-cross-chain-validation/README.md

@@ -0,0 +1,53 @@
+---
+ics: 28
+title: Cross-Chain Validation
+stage: draft
+category: IBC/APP
+requires: 25, 26
+kind: 
+author: 
+created: 
+modified: 
+---
+
+<!-- omit in toc -->
+# Synopsis
+
+This standard document specifies packet data structure, state machine handling logic, and encoding details for Cross-Chain Validation (CCV). CCV is the specific IBC level protocol that enables *Interchain Security*, a Cosmos-specific category of *Shared Security*.
+
+At a high level, CCV enables a *provider chain* (e.g., the Cosmos Hub) to provide *security* to multiple *consumer chains*. This means that the validator sets on the consumer chains are chosen from the validator set of the provider chain (for more details, see the [Security Model](./overview_and_basic_concepts.md#security-model) section).
+
+The communication between the provider and the consumer chains is done through the IBC protocol over a *unique*, *ordered* channel (one for each consumer chain). 
+
+> Throughout this document, we will use the terms chain and blockchain interchangeably.
+
+## Contents
+- [Overview and Basic Concepts](./overview_and_basic_concepts.md)
+- [System Model and Properties](./system_model_and_properties.md)
+- [Technical Specification: Data Structures and Methods](./technical_specification.md)
+
+<!--
+## Backwards Compatibility
+
+(discussion of compatibility or lack thereof with previous standards)
+
+## Forwards Compatibility
+
+(discussion of compatibility or lack thereof with expected future standards)
+
+## Example Implementation
+
+(link to or description of concrete example implementation)
+
+## Other Implementations
+
+(links to or descriptions of other implementations)
+
+## History
+
+(changelog and notable inspirations / references)
+ -->
+
+## Copyright
+
+All content herein is licensed under [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0).