Evidence chain of custody record
Hypothetical. Not a client, not a result.
// The problem
A police service tracks physical and digital evidence on paper logs between the property room, the forensic lab and court, and each transfer depends on a signature that can go missing.
// What we would build
Barcoded evidence labels printed at intake, every transfer scanned and signed, and digital files fingerprinted at intake with each fingerprint and transfer recorded on a private ledger the service and its partner forensic lab each run a node of, on servers the service controls. A well-audited database with signed logs often does this job alone, and we will say so.
// What is in it
- Barcode labels printed at intake and scanned at every transfer
- Digital files fingerprinted so any change after intake shows
- Transfers, signatures and locations recorded on a private ledger
- Disclosure packages exported with the full custody history
- Servers on premises, with label printers and scanners listed by quantity
// Stack
- Next.js
- Hyperledger Besu (private, permissioned)
- PostgreSQL
- Barcode label printers and scanners
- On-premise servers
// estimate
- Build
- ≈ US$151,000 to US$230,000, delivered within 33 weeksCAD 214,900 to 327,400
- Support
- ≈ US$2,500 a monthCAD 3,565 a month
- Hardware
- ≈ US$14,500 to US$24,800CAD 20,670 to 35,270
Prices in your currency are estimates from today's Bank of Canada rate. All invoicing is in CAD or USD.
Timeline by milestone
- Discovery
- 2.9 to 3.4 weeks
- Architecture
- 0.4 weeks
- Design approved
- 3.4 to 5.9 weeks
- Core features
- 1.9 to 2.9 weeks
- Full build
- 1.4 to 1.9 weeks
- Devnet
- 3.4 to 5.9 weeks
- Testing and fixes
- 0.4 weeks
- Testnet
- 2.9 to 3.4 weeks
- Penetration test findings closed
- 2.9 to 3.4 weeks
- Custody walkthrough with your evidence unit
- 2.9 to 3.4 weeks
- Launch
- 0.9 to 1.4 weeks
- Mainnet
- 0.9 to 1.4 weeks
Outside our hands, and added to the calendar
- Hardware delivery, after it is ordered
- 2 to 6 weeks
- CAD interface access from your vendor
- 1 to 4 weeks
- Independent penetration test and retest
- 2 to 4 weeks
How it is paid
- Deposit 20%
- CAD 42,980 to 65,480
- Discovery 1.9%
- CAD 4,083.10 to 6,220.60
- Architecture 5.2%
- CAD 11,174.80 to 17,024.80
- Design approved 1.9%
- CAD 4,083.10 to 6,220.60
- Core features 5.9%
- CAD 12,679.10 to 19,316.60
- Full build 3.9%
- CAD 8,381.10 to 12,768.60
- Devnet 15.7%
- CAD 33,739.30 to 51,401.80
- Testing and fixes 1.9%
- CAD 4,083.10 to 6,220.60
- Testnet 10.4%
- CAD 22,349.60 to 34,049.60
- Penetration test findings closed 7.7%
- CAD 16,547.30 to 25,209.80
- Custody walkthrough with your evidence unit 7.7%
- CAD 16,547.30 to 25,209.80
- Launch 1.9%
- CAD 4,083.10 to 6,220.60
- Mainnet 5.9%
- CAD 12,679.10 to 19,316.60
- Holdback, 30 days after launch (10%)
- CAD 21,490 to 32,740
- Rack server x 1
- CAD 14,200 to 28,800. Billed up front, at cost, outside the milestones
- Desktop label printer x 4
- CAD 3,490. Billed up front, at cost, outside the milestones
- Corded barcode scanner x 4
- CAD 1,180. Billed up front, at cost, outside the milestones
- Labels and ribbons, starter stock x 6
- CAD 1,800. Billed up front, at cost, outside the milestones