Add: Docs for CoMID Template Format

Signed-off-by: Ravjot Singh <[email protected]>

data/comid/README.md

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+
+# CoMID Template Format
+
+## 1 Introduction
+
+**CoMID (Concise Model Identifier)**,  is a data model and serialization format (in JSON) for capturing **reference values** and **verification keys** that can be used in remote attestation and other trust-verification scenarios. By standardizing how measurements are captured and shared, CoMID facilitates **interoperability**, **integrity**, and **traceability** across various systems and vendors.
+
+## 2 Template Structure
+
+A CoMID template is a JSON document composed of **top-level fields** and a **triples** object. The **top-level fields** provide overall identification, language, and authorship, while the **triples** object contains domain-specific data (e.g., reference values, attester keys).
+
+```
+{
+  "lang": "<language-region>",
+  "tag-identity": { ... },
+  "entities": [ ... ],
+  "triples": {
+    "reference-values": [ ... ],
+    "attester-verification-keys": [ ... ]
+    ...
+  }
+}
+``` 
+
+### 2.1 Top-Level Fields
+
+-   **lang** (`String`): Defines the language or locale (e.g., `"en-GB"`).
+-   **tag-identity** (`Object`): Uniquely identifies this CoMID document via an ID (often a UUID) and includes a version number.
+-   **entities** (`Array`): Lists the entities (organizations, individuals, etc.) contributing to or maintaining the document, along with their roles.
+
+### 2.2 Triples
+
+-   **reference-values**: One or more **reference-value** objects, each containing an **environment** and one or more **measurements**.
+-   **attester-verification-keys**: One or more **attester-verification-key** objects, each containing an **environment** and an array of **verification-keys**.
+
+
+## 3 Components
+
+### 3.1 Environment
+
+An **environment** captures the context of a measurement or verification key:
+
+-   **class**: Vendor, model, and possibly an ID (`type` + `value`).
+-   **instance** (`optional`): For distinguishing multiple instances of the same environment (e.g., using `ueid` or `uuid`).
+-   **layer** and **index** (`optional`): For layered environments (e.g., DICE layers in multi-stage boot processes).
+
+### 3.2 Measurements
+
+Each measurement has two crucial subfields:
+
+-   **key**: Identifies the measurement, including possible fields like `label`, `version`, and `signer-id`.
+-   **value**: Holds the actual measurement data (e.g., cryptographic digests, raw values, or operational flags).
+
+### 3.3 Attester Verification Keys
+
+Used to store **public keys** associated with an environment. This is essential for verifying the attestation claims or measurement signatures produced by that environment.
+
+## 4 Field-By-Field Explanation
+
+### 4.1 Global Fields
+|     Field    	|  Type  	|                       Description                       	|                    Example                   	|   	
+|:------------:	|:------:	|:-------------------------------------------------------:	|:--------------------------------------------:	|
+| lang         	| String 	| Language/country code.                                  	| "en-GB"                                      	|   	
+| tag-identity 	| Object 	| Identity of this CoMID tag (UUID + version).            	| "id": "43BBE37F-2E61-4B33-AED3-53CFF1428B16" 	|   	
+| entities     	| Array  	| The organizations/roles associated with this CoMID tag. 	| [ { "name": "ACME Ltd." ... } ]              	|   	
+
+### 4.2 Reference-Value Fields
+|        Field       |  Type  |                                     Description                                    |                                            Example                                            |
+|:------------------:|:------:|:----------------------------------------------------------------------------------:|:---------------------------------------------------------------------------------------------:|
+| environment        | Object | Contains class and optionally instance, layer, index.                              | See 3.1 Environment.                                                                          |
+| measurements       | Array  | List of measurement objects.                                                       | [ { "key": { ... }, "value": { ... } } ]                                                      |
+| measurements.key   | Object | Identifies the measurement. Could be a psa.refval-id, cca.platform-config-id, etc. | { "type": "psa.refval-id", "value": { "label": "BL", "version": "2.1.0", ... } }              |
+| measurements.value | Object | Holds the actual measurement data.                                                 | { "digests": ["sha-256:..."] }, or { "raw-value": { "type": "bytes", "value": "..." } }, etc. |
+
+### 4.3 Attester-Verification-Key Fields
+|       Field       |  Type  |               Description               |                                   Example                                   |
+|:-----------------:|:------:|:---------------------------------------:|:---------------------------------------------------------------------------:|
+| environment       | Object | Defines the environment for these keys. | See 3.1 Environment.                                                        |
+| verification-keys | Array  | Holds one or more public keys.          | [ { "type": "pkix-base64-key", "value": "-----BEGIN PUBLIC KEY-----..." } ] |
+----------
+
+### 5 High Level Structure for CoMID Templates
+
+![CoMID Template Structure](https://drive.google.com/file/d/1b6lURF52BOqU569APLQj6PwAEN_qSGJv/view?usp=sharing)