Sections 3 & 5
Resilience by measured degradation
The system is not impossible to shut down. It is designed to remain useful through internet shutdowns, tolerate partial telecom failure, preserve records during local isolation, and recover cleanly when connectivity returns.
Feature phone / Smartphone / Shelter terminal
│
Amrao Achi Safety Service
│
JOGAJOG Event and Relay Layer
/ │ │ \
SMS Wi-Fi Internet Volunteer bundle
\ │ │ /
Independent replicated community nodes
│
Authorized family response
System layers
User interfaces
SMS, numeric aliases (1 / 2 / 0), Bangla IVR, and an offline Wi-Fi captive portal.
Node services
Parser, local database, queue, authorization, rate limiter, and replay cache on each independent relay.
Transport adapters
Approved operator/A2P SMS, internet HTTPS, local Wi-Fi, Bluetooth, and encrypted bundle import/export.
Trust services
Root and regional node certificates, HMAC token keys, bulletin signatures, and audit logs.
Coordination layer
Non-authoritative regional dashboards. Failure here never stops local check-in or lookup.
Threats this design addresses
- Internet or social-platform shutdown
- Failure or blocking of one SMS gateway or receiving number
- Malicious check-in submitted for another person
- Unauthorized mass lookup or stalking
- Fake emergency bulletin claiming to be official
- Duplicate, delayed, or out-of-order SMS delivery
- A valid old event replayed to fake a current status
- A node key improperly issued, retained, or revoked
Regulatory-compliant SMS
Production messaging runs only through operator-approved A2P or short-code routes via licensed aggregators. No unsanctioned multi-SIM modem banks — this demo uses a simulated route.
Privacy by construction
Phone numbers are never replicated in the clear. A versioned HMAC-derived blind index (the "person token") is the only cross-node lookup key.