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088230	R. Bishop	2025-03-06 23:44:25	1	# Wiegand Protocol & Access Control
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			3	## Understanding the Wiegand Protocol
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			5	The Wiegand protocol is a widely used data transmission format in access control systems, originally based on the Wiegand effect but now primarily used as a standard for communication between card readers and controllers. It is commonly found in proximity card readers, keypads, and biometric access devices.
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			7	The Wiegand protocol is simple, reliable, and widely supported, but it has security limitations that organizations should consider when implementing or upgrading access control systems.
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			9	---
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			11	## Why Wiegand is Important
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			13	The Wiegand protocol remains relevant due to:
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			15	- Industry Standardization → Supported by most access control systems worldwide.
			16	- Simple & Efficient Communication → Uses a straightforward bitstream for transmitting credentials.
			17	- Compatibility with Legacy Systems → Many existing access control installations still rely on Wiegand.
			18	- Low-Cost Implementation → Does not require complex encryption or advanced processing.
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			20	Despite its advantages, Wiegand has security weaknesses, including lack of encryption, susceptibility to replay attacks, and limited data transmission length.
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			22	---
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			24	## Wiegand Protocol Structure
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			26	The Wiegand protocol transmits data in a binary format using two signal lines: Data0 (D0) and Data1 (D1). The most common Wiegand formats are 26-bit, 34-bit, and 37-bit, though custom formats exist.
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			28	### Common Wiegand 26-Bit Format
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			30	\| Bit Position \| Description \|
			31	\|-------------\|------------\|
			32	\| 1 \| Leading Parity Bit (Even parity for the first 13 bits) \|
			33	\| 2 - 9 \| Facility Code (Identifies the site or organization) \|
			34	\| 10 - 25 \| Card Number (Unique credential identifier) \|
			35	\| 26 \| Trailing Parity Bit (Odd parity for the last 13 bits) \|
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			37	### Wiegand Data Transmission
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			39	- Idle State → Both D0 and D1 lines remain HIGH.
			40	- Data Transmission → A LOW pulse on D0 represents a binary `0`, while a LOW pulse on D1 represents a binary `1`.
			41	- Bit Timing → Each pulse lasts approximately 50 µs, with inter-bit spacing of 1-2 ms.
			42	- Parity Checking → The first and last bits serve as parity bits to detect errors.
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			44	---
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			46	## How Wiegand Readers Transmit Data
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			48	1. Card Detection → When a card or credential is presented, the reader extracts the stored binary data.
			49	2. Bitstream Transmission → The reader transmits the credential as a sequence of D0 and D1 pulses.
			50	3. Controller Processing → The access control panel decodes the bitstream, checks the facility code and card number, and verifies access permissions.
			51	4. Access Decision → Based on the credentials, the system grants or denies access.
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			53	---
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			55	## Security Considerations
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			57	While Wiegand is widely used, it has several security concerns:
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			59	- Lack of Encryption → Data is transmitted in plain text, making it susceptible to interception.
			60	- Replay Attacks → Captured Wiegand signals can be replayed to gain unauthorized access.
			61	- Fixed Card Numbers → Cannot support dynamic or rolling security codes.
			62	- Limited Distance → Wiegand signals degrade beyond 500 feet (150 meters) without signal boosters.
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			64	To improve security, organizations should:
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			66	✅ Upgrade to encrypted credential formats such as OSDP (Open Supervised Device Protocol).
			67	✅ Use multi-factor authentication with PINs or biometrics.
			68	✅ Implement end-to-end encryption for access control data transmission.
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			70	---
			71
			72	## Migration Considerations
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			74	Organizations moving away from Wiegand should consider:
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			76	1. Evaluating Current System Compatibility → Determine if controllers and readers support OSDP or other secure alternatives.
			77	2. Deploying Secure Communication Protocols → OSDP with AES encryption is a modern replacement for Wiegand.
			78	3. Upgrading Card Credentials → Implementing HID Seos, MIFARE DESFire, or smart cards improves security.
			79	4. Enhancing Authentication Methods → Consider multi-factor authentication using biometrics or mobile credentials.
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			81	While Wiegand remains in use, organizations should transition to more secure protocols to mitigate security risks.
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			83	---
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			85	## Final Thoughts
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			87	The Wiegand protocol has been a cornerstone of access control technology, but its security weaknesses require organizations to consider modern alternatives. To ensure secure access control, businesses should:
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			89	✅ Evaluate the security risks of legacy Wiegand systems.
			90	✅ Implement OSDP or encrypted credential formats for better protection.
			91	✅ Use modern authentication technologies to prevent cloning and replay attacks.
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			93	By transitioning from Wiegand to more secure protocols, organizations can ensure future-proof access control with enhanced security and reliability.