Turn the cameras that are already on the border into verifiable intelligence
Prahari is a software layer over existing CCTV — no new hardware. Its contribution is a cryptographically verifiable chain of custody: every event is sealed into a two-tier, countersigned hash-ledger (the edge node writes, the sector core notarizes with a key the node never holds), so surveillance evidence is tamper-resistant and admissible under BSA §65B — even after a three-day uplink outage at a remote outpost.
🔗 Two-tier ledger
Edge writes an append-only SHA-256 chain; the core countersigns each head. History the core witnessed cannot be rewritten undetected — try it in the Evidence tab.
🛰️ Existing CCTV
Measures what each degraded camera can actually do (IEC 62676-4 DORI), then grants analytics per image region. Fenced tripwires or open-border pattern-of-life.
🌙 Built for the real border
Runs day, night (IR), and thermal; reads Indian number plates; survives the offline uplink. Infiltration happens after dark — so does Prahari.
Six cameras — real pipeline output
Detections, tracks, zones, plates and the thermal/night styling are drawn by the node. These are short captures of the live system.
Tamper-evident → tamper-resistant, live
The edge hash chain alone is tamper-evident: a naive edit breaks a link. But an insider who edits an event and re-stamps every following hash produces a chain the edge's own check accepts. The sector core defeats that by countersigning each chain head with a key no node holds. Run it:
| # | Event | Score | Entry hash |
|---|
Edge chain check
Core countersignature (notary)
Indian number-plate recognition
The gate camera is certified for ANPR only where the measured scale clears 250 px/m (IEC DORI Identify) — Prahari refuses to guess a plate it cannot resolve, rather than emit garbage. Where it can, a hybrid reader (fast-alpr detection + Awiros PP-OCRv5, an Apache-2.0 Indian specialist) reads the characters.
Sample live reads from the footage:
MP 04 YK 621 · KA 51 A 0120 · TN 55 3504 · HP … · KA 66 0
MP = Madhya Pradesh · KA = Karnataka · TN = Tamil Nadu · HP = Himachal Pradesh. Non-plate text (shop boards, hoardings) is dropped by the Indian-plate format check.
Measured results
Every number is reproducible from a script in the repo. Nothing here is a projection.
| Capability | Result | Kind | Note |
|---|
Honesty stance: negative results are kept visible. The Event Priority Score is a ranking aid, not a calibrated probability, and has not been validated against border ground truth.
Security posture (STRIDE)
The one honest headline: the ledger is tamper-resistant via core countersigning today, on a symmetric-HMAC trust root. HSM-backed asymmetric signing and external anchoring are the next steps — designed for, not claimed as built.
Full code, tests and threat model: github.com/sayaksatpathi/PRAHARi