A Blockchain Safety Net for Passenger Data

1. The privacy-versus-security headache

Every year Europe’s Passenger Information Units (PIUs) collect hundreds of millions of booking records—names, seats, bag weights, payment slips—known as Passenger Name Records (PNRs).
The data are vital for spotting drug mules, trafficking routes or terror suspects, yet they are also deeply personal. EU law therefore demands:

mask identities after 6 months
delete everything after 5 years
log every single access
share only with vetted partners

Traditional file exchanges or e-mail satisfy none of these points: logs can be edited, copies leak, and nobody can prove later who touched which record when.
Enter blockchain—a technology famous for cryptocurrencies but far better at tamper-proof audit trails.

2. Why a simple database is not enough

A central warehouse (think “PNR cloud”) looks convenient, but is subject to risks:

Risk	Example
Insider threat	Rogue analyst downloads entire set
Tampering	Someone re-opens a closed case
Repudiation	Officer denies requesting the data
Availability	Single hack takes all systems down

What security engineers need is decentralisation, cryptographic logging and fine-grained access control without building separate national silos.

3. Blockchain 101 for aviation intelligence

Key ideas in blockchain:

Ledger = append-only spreadsheet copied to every approved node
Each row = hash of content + previous row → change one letter, break the chain
Smart contracts = small programs that fire only when pre-defined rules are met
Permissioned network = only accredited PIU nodes may join; no anonymous miners

4. How TENACITy wired a blockchain into real border policing

TENACITy is building a modular toolbox that helps PIUs fuse PNR with open-source intel, risk-scoring AI and pattern-mining engines. Its blockchain communication module, developed by Brno University of Technology, handles the most sensitive step: unit-to-unit data exchange.

4.1 Design choices

Requirement	Technical answer
Keep data EU-only	Hyperledger Fabric permissioned network
Hide payload from third parties	Private-data collections + off-chain encrypted blob storage
Prove nothing was altered	Store only hashes on-chain
Automatic deletion	Chaincode flags blobs for purge after legal deadline
No gas fees	Fabric’s Raft consensus, no Proof-of-Work

4.2 Life of a typical request

Officer in PIU-A opens TENACITy dashboard → hits “Request legs for passenger XYZ”
API server writes a hashed request onto the channel; only PIU-B can decrypt the blob
PIU-B chaincode checks endorsement policy, attaches encrypted PNR, timestamps response
Both sides confirm receipt; payload hashes remain, blobs are cryptographically erased
Any auditor can later verify: “Yes, hash ABC was written by PIU-A at 09:14:07 and answered by PIU-B at 09:18:22”—without ever seeing the raw PNR

5. Early numbers & lessons

Pilot network spans 6 EU PIUs, 12 peer nodes, <1 s latency inside Europe
Throughput tested at 2 000 request/response pairs per hour—enough for daily peaks
Over 80 % of test users rated the blockchain log “more trustworthy” than classical e-mail exchange
Legal team likes built-in deletion: no forgotten files lingering on FTP servers

6. Take-away

Blockchain is not magic, but tamper-proof logging + programmable deletion + mutual distrust is exactly what PNR law demands. Within TENACITy the ledger is no cryptocurrency – it is a digital notary that lets border analysts share vital clues while proving, beyond doubt, that citizens’ rights were respected every step of the way.