Barcode & QR Code Reading¶
Definition¶
Many identity documents contain machine-readable codes — PDF417 barcodes, QR codes, or Data Matrix — encoding structured data that can be extracted quickly and validated against visually printed information.
Code Types on ID Documents¶
| Code Type | Found On | Data Encoded |
|---|---|---|
| PDF417 | US/Canadian driving licenses, some IDs | AAMVA standard: name, DOB, address, DL class, restrictions |
| QR Code | India Aadhaar, some EU IDs | Digitally signed identity data |
| Data Matrix | Some EU IDs, residence permits | Encoded identity fields |
| 1D Barcode | Older documents | Document number, basic data |
Aadhaar QR Code¶
India's Aadhaar QR contains digitally signed XML — verifiable offline:
| Feature | Details |
|---|---|
| Content | Name, DOB, gender, address, photo (optional), last 4 digits of Aadhaar |
| Signature | UIDAI digital signature — cryptographically verifiable |
| Offline verification | No internet needed — just validate signature against UIDAI public key |
| Photo in QR | Newer Aadhaar cards include compressed face photo in QR |
Key Takeaways¶
Summary
- Barcodes/QR codes provide machine-readable, pre-structured data — faster than OCR
- PDF417 is standard on US/Canadian driving licenses (AAMVA format)
- Aadhaar QR enables offline verification with digital signature — critical for India eKYC
- Cross-validating barcode data with OCR data detects tampering (altered visible text won't match barcode)