OSDP and Wiegand offline decoding
Decode synthetic reader messages locally. Compare electrical framing, payload interpretation and authentication without using real credentials or hardware.
Sources and scopeSource record 25 August 2026
Technical source record: 25 August 2026. Check the linked documentation for current product requirements.
Offline synthetic comparison only; detailed OSDP content requires the licensed standard, and field acceptance is outside lab scope.
On this page
Overview#
Lab class: Offline synthetic fixture
Purpose#
Understand that physical signalling, frame error detection, supervision and authenticated encryption are different properties. IEC 60839-11-5 and the full OSDP specification are licensed; normative frames and keys are excluded from the fixture.
Wiegand exercise#
Using an invented bit string whose format is explicitly supplied with the fixture, identify parity positions, facility/site field, credential number field, total width, and ambiguity. Document that parity detects limited transmission errors but doesn't authenticate a reader or credential and that bit field formats vary.
Don't capture a real credential, infer a site's card format, clone/replay a card, or connect to operational reader wiring.
OSDP review exercise#
From official SIA overview material and a licensed standard where lawful access is available, map controller/peripheral roles, multidrop addressing, supervision, capabilities, secure channel purpose, key provisioning/rotation, installation/default key risk, downgrade/fallback policy, and conformance testing. Use only synthetic metadata, never live keys or frames.
Comparison record#
| Property | Wiegand style signaling | OSDP design question |
|---|---|---|
| Direction | Commonly reader to controller | Which bidirectional commands/replies are required? |
| Supervision | Limited by implementation | How is loss/tamper detected and alerted? |
| Confidentiality/authentication | Not inherent | Is Secure Channel required and correctly provisioned? |
| Addressing/topology | Often dedicated conductors | How are multidrop address and bus constraints managed? |
| Migration | Existing panels/readers/format | Is fallback disabled and key lifecycle operational? |
Evidence checklist#
- Synthetic bit string, declared format, provenance, and digest recorded
- Bit width, field boundaries, parity positions, and ambiguity identified without inferring a real site format
- Signaling, error detection, supervision, confidentiality, and authentication kept distinct
- OSDP controller/peripheral roles, addressing, capabilities, and supervision mapped from lawful sources
- Secure Channel provisioning, rotation, default key, downgrade, and fallback questions documented
- Migration assumptions and conformance evidence requirements recorded
- Real credential data, keys, frames, cards, readers, panels, and field wiring excluded
Sources#
- SIA OSDP, version/status overview, accessed 25 August 2026.
- IEC 60839-11-5:2020, catalogue entry, accessed 25 August 2026.