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Physical Security & Locksmithing Glossary

Key terminology and technical concepts referenced throughout the wiki.

A​

  • Amplitude Shift Keying (ASK): A low-frequency RFID modulation scheme that alters the amplitude of the carrier wave to represent binary data (e.g., EM4100).
  • Astragal: A vertical molding or plate attached to the meeting edge of a door to cover the gap and protect latch hardware from external tampering.
  • Auxiliary Deadlatch Pin: A secondary small pin alongside a latch bolt that, when depressed by the strike plate, prevents the main latch from being depressed or slipped.

B​

  • Bitting: The specific pattern of depth cuts on a key blade designed to set pins or wafers to the correct heights.
  • Between Cut Centers (BCC): The distance between consecutive cut positions along a key blade.
  • Bottom of Keyway (BOK): Applying rotational tension by placing the wrench at the bottom (pin side) of the keyway.
  • Build-up Pin (Control Pin): In SFIC systems, the specific pin placed in the chamber to bridge the difference between the operating cut and the control cut.

C​

  • Contact Area: The angular span between the Left Contact Point and Right Contact Point on a safe lock drive cam.
  • Contact Point: The specific rotational position on a safe dial where the lever nose makes metal-on-metal contact with the drive cam gate edges.
  • Control Key: A dedicated key used in interchangeable core (SFIC/LFIC) systems to rotate the control sleeve and extract the core from its housing.
  • Control Shear Line: The secondary upper shear plane in an SFIC cylinder that allows the control sleeve to turn independently of the plug.
  • Core (Plug): The inner rotating portion of a lock cylinder that turns to activate the locking cam or tailpiece.
  • Crash Bar: A horizontal egress device that unlatches a door when push pressure is applied.
  • Crypto-1: The proprietary stream cipher designed by NXP Semiconductors for MIFARE Classic RFID smartcards.

D​

  • De Bruijn Sequence: A cyclic sequence of characters from a given alphabet for which every possible sequence of length n appears as a substring exactly once; used to minimize keypad brute-force keystrokes.
  • Drive Cam: The primary disc in a mechanical safe lock attached to the dial spindle that drives the wheel pack and features the drop-in gate.
  • Drop-In: The mechanical event during safe lock dialing when all wheel gates align beneath the fence, allowing the lever nose to enter the drive cam gate.

E​

  • Effective Plug Diameter (EPD): The outer diameter of a lock cylinder plug body.
  • ESPkey: An open-source hardware implant installed inline on a Wiegand bus to passively sniff, log, and replay badge credentials.

F​

  • Facility Code (FC): An 8-bit to 16-bit integer embedded within an access control credential bitstream designating the specific enterprise or installation site.
  • Fail-Safe: An electric lock that unlocks automatically when electrical power is interrupted (e.g., standard magnetic locks).
  • Fail-Secure: An electric lock that remains mechanically locked when electrical power is lost (e.g., standard electric strikes).
  • False Set: A slight rotation of the plug that occurs when a spool or security pin catches on its narrow waist rather than fully setting.
  • Fence: A rigid crossbar attached to the lever of a safe lock that must enter all wheel gates simultaneously to permit unlocking.
  • Frequency Shift Keying (FSK): A modulation technique used in RFID systems (e.g., HID Prox) that toggles between two subcarrier frequencies to transmit data.

G​

  • Gate: A rectangular notch milled into the outer circumference of a safe lock wheel disc.
  • Gate Signature: A measurable shift or narrowing of the dial contact area indicating that a wheel gate has passed under the fence.

I​

  • iCLASS Elite: A high-security configuration of HID iCLASS credentials utilizing a customized enterprise cryptographic key rather than standard factory keys.
  • Independent Service (IND): An elevator operating mode that removes the car from the automated dispatch group, allowing exclusive manual control from within the cab.
  • Interchangeable Core (IC): A modular cylinder engineered to be extracted and replaced in seconds using a control key without hardware disassembly.

L​

  • Left Contact Point (LCP): The dial position where the lever nose contacts the left shoulder of the safe lock drive cam gate.
  • loclass: An open-source cryptographic attack against HID iCLASS readers that recovers secret Elite Master Keys by simulating credentials to harvest reader authentication MACs.
  • Lost Motion: Mechanical play engineered into safe lock drive flys that allows wheels to be parked while other wheels rotate in the opposite direction.

M​

  • Maximum Adjacent Cut Specification (MACS): The maximum allowable numerical depth difference between adjacent cuts on a key blade.
  • Multiplex Keyway: A hierarchical family of keyway wardings featuring change keys, multi-section sub-masters, and all-section grand master keys.

O​

  • 1-Wire: A low-speed single-data-conductor serial communications bus developed by Dallas Semiconductor for iButton fobs and sensors.
  • Operating Shear Line: The primary shear boundary in an interchangeable core that allows the inner plug to turn and operate the lock throw.

P​

  • Paracentric: A lock keyway design where warding projections extend past the vertical centerline of the key blade.
  • Phase 1 Emergency Recall: An automated or key-triggered elevator life safety state that returns all cars non-stop to the ground floor.
  • Phase 2 Emergency In-Car Operation: A key-controlled elevator mode allowing firefighters to manually navigate the car during emergencies.
  • Phase Shift Keying (PSK): An RFID modulation scheme (e.g., Indala) that shifts the phase of the carrier waveform.

R​

  • Request to Exit (REX): A sensor (PIR, motion, or switch) designed to detect an occupant approaching an exit and signal the electronic access system to unlock the door.
  • Right Contact Point (RCP): The dial position where the lever nose contacts the right shoulder of the safe lock drive cam gate.

S​

  • Shear Line: The circular boundary plane between the rotating plug and the stationary cylinder housing.
  • Single Pin Picking (SPP): The method of lifting each pin individually to the shear line while feeling for binding order.
  • Small Format Interchangeable Core (SFIC): A standardized figure-eight interchangeable core format based on the Best A-2/A-3/A-4 architecture.
  • Stack Constant: The required total height of all components in an SFIC chamber stack (equal to 23 steps in the Best A-2 system).

T​

  • T5577: An Atmel/Microchip multi-standard rewritable RFID transponder chip capable of emulating nearly any 125 kHz credential.
  • To First Cut (TFC): The distance from the key stop reference point (shoulder or tip) to the center of the first pin cut.
  • Top of Keyway (TOK): Placing a flat tension prybar at the top of the keyway to maximize pick mobility.

W​

  • Wheel Pack: The assembly of coaxial combination discs and drive flys inside a mechanical safe lock.
  • Wiegand Protocol: A standard 2-wire (Data 0 / Data 1) unidirectional communications interface connecting card readers to access control panels.