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docs/CHANGELOG.md

@@ -1,5 +1,13 @@
 # HyperCortex Mesh Protocol — Changelog
 
+## HMP-0005 (February 2026) — Core Specification v5.0.2
+
+**Security & Cryptography:**
+* Introduced optional `key-disclosure` container for controlled symmetric key sharing.
+* Enabled delayed and conditional decryption workflows (e.g., post-consensus, escrow, staged disclosure).
+
+No breaking changes. Fully backward-compatible within the 5.0.x series.
+
 ## HMP-0005 (October 2025) — Core Specification v5.0
 
 **Architecture:**
@@ -172,4 +180,3 @@ This version supersedes all RFC-based HMP 4.x specifications.
 * Provided high-level example workflows (goal creation, task delegation, concept consensus).
 * Laid out an initial Future Work list, covering scalability, cross-mesh interoperability, and quantum networking as exploratory directions.
 * Established the RFC document structure and versioning approach for further evolution.
-

docs/HMP-0005.md

@@ -1,6 +1,6 @@
 # HyperCortex Mesh Protocol (HMP)
 
-**Version: 5.0.0**
+**Version: 5.0.2**
 **Document ID:** HMP-0005  
 **Status:** Stable  
 **Category:** Core Specification  
@@ -801,10 +801,10 @@ a multi-dimensional system used to represent conceptual relations numerically or
    | `key_recipient`   | string | Symmetric key encrypted with the recipient’s public key (hybrid encryption envelope). |
    | `payload_type`    | string | Recommended prefix `encrypted+` (e.g., `encrypted+zstd+json`).                         |
 
-6. **Relationship between `recipient` and `key_recipient`:**
+6. **Recipient fields:**
 
-    * When encryption is applied, the container MUST have exactly **one** recipient.
-    * For multiple recipients, encryption is **not** used; the payload remains in plaintext.
+   * When `recipient` is used, exactly one recipient MUST be specified.
+   * For encrypted delivery to multiple recipients, the `group_recipient` mechanism (see 3.19) MUST be used.
 
 > ⚙️ **Note:** Agents may forward encrypted containers even if they cannot decrypt them, maintaining store-and-forward behavior.
 ---
@@ -7052,6 +7052,40 @@ All such interpretations are outside the scope of HMP.
 
 ---
 
+### 12.6 Key Disclosure Container (`key_disclosure`)
+
+The `key_disclosure` container is used to disclose the symmetric key used to encrypt the payload of a previously encrypted container.
+
+This mechanism enables delayed or selective disclosure without modifying the original container.
+
+#### Container structure
+
+```json
+{
+  "head": {
+    "class": "key_disclosure"
+  },
+  "payload": {
+    "target_container": "did:hmp:container:abc123",
+    "symmetric_key": "BASE64URL(...)"
+  },
+  "related": {
+    "disclosure": ["did:hmp:container:abc123"]
+  }
+}
+```
+
+#### Semantics
+
+1. The original container remains immutable.
+2. The `symmetric_key` MUST be Base64URL-encoded.
+3. The disclosed symmetric key MUST successfully decrypt the target container’s payload and produce content matching its `payload_hash`.
+4. The container MAY itself be encrypted (see 3.9 and 3.19).
+5. Multiple `key_disclosure` containers MAY reference the same target.
+6. The container SHOULD reference the target using the `related.disclosure` field to enable efficient backlink indexing.
+
+---
+
 ## 13. Experimental Extensions
 
 Experimental Extensions describe mechanisms that are intentionally exposed for exploration, prototyping, and architectural discovery.
@@ -7129,6 +7163,7 @@ All items below represent *potential extensions* for the 5.x family.
 | External Protocol Identifiers (`peer_announce.other_protocols`)   | Recommended  | 12.5.2 / 14.11    | Likely             |
 | External Resources / Container Storage (`peer_announce.external`) | Recommended  | 12.5.3 / 14.12    | Likely             |
 | Identity Cost and Anti-Sybil Signaling                            | Recommended  | 12.5.4            | Likely             |
+| Key Disclosure Container (`key_disclosure`)                       | Recommended  | 12.6              | Likely             |
 | Key Rotation and Recovery                                         | Experimental | 13.1 / 14.3.2     | Unknown            |
 | Proxy Keys and Encrypted Routing                                  | Research     | 14.3.3            | Unknown            |
 | Reputation Mesh                                                   | Research     | 14.1.1            | Likely             |