mGuard

# Trust Model

## Signing chain

![](cert signing chain.png)

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## Trust Model

![trust anchor](Group 71.png)

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## Component identities

**Root / Site CA**

**Identity:** `/ndn/md2k`

**Type:** Self-signed root CA

**Trust Anchor:** `md2k-trust-anchor.ndncert`

All components ultimately chain to this root.  

Consumers load this file so they can trust any certificate issued under `/ndn/md2k`.

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##  **Identities Signed by the Root CA**

The root `/ndn/md2k` signs:

- `/ndn/md2k/mguard/controller`

- `/ndn/md2k/mguard/aa`

- `/ndn/md2k/mguard/dd40c` (producer)

- All consumer identities (example: `/ndn/md2k/adam`)

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## **Stream Identities Signed by the Producer**

The producer identity `/ndn/md2k/mguard/dd40c` signs all stream identities:

- `/ndn/md2k/mguard/dd40c/phone/accelerometer`

- `/ndn/md2k/mguard/dd40c/phone/gyroscope`

- `/ndn/md2k/mguard/dd40c/phone/gps`

- `/ndn/md2k/mguard/dd40c/phone/battery`

- `/ndn/md2k/mguard/dd40c/data_analysis/gps_episodes_and_semantic_location`

These stream identities are used to sign **manifests**, **encrypted DATA**, and **CK packets**.

The producer must now serve the certificates for these streams  

(interest filter on each stream's certificate prefix).

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## **Producer Behavior**

Producer validates:

- AA public parameters (`/aa/PUBPARAMS`)

Producer signs:

- Stream manifests (RSA) using stream identity certificates  

- CK packets (digest)  

- Encrypted data (digest)

Producer serves:

- Producer certificate  

- All stream certificates  

Producer no longer signs manifests with its own identity;  

manifests are now signed by stream identities.

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##  **Consumer Behavior**

The consumer performs the most validation.

Consumer validates:

- AA parameters (RSA)

- DKEY segments (RSA)

- Controller POLICYDATA (RSA)

- Stream manifests (RSA)

- CK packets (digest)

- Encrypted data segments (digest)

All rules validated using the consumers trust schema.

Consumer decrypts:

1. Encrypted application DATA → extract CK name  

2. Fetch CK → decrypt with DKEY  

3. Decrypt DATA using CK

The consumer uses three rules:

1. **AA public parameters and DKEY validation**  

   `/ndn/md2k/mguard/aa/*` signed by AA (RSA), chaining to root.

2. **Controller POLICYDATA replies**  

   `/ndn/md2k/mguard/controller/*` signed by controller (RSA), chaining to root.

3. **Stream and producer content**  

   `/ndn/md2k/mguard/dd40c/*`  

   Allows:

   - `sha256` (digest) for encrypted DATA, CK, metadata  

   - `rsa-sha256` for manifests, stream certs  

   KeyLocator must be a prefix of the Data name.

All validations ultimately chain back to `/ndn/md2k`.