HSA210 – Secure Headphone Diode

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The HSA210 is the world’s first device that fully secures stereo analog audio output stream to prevent audio eavesdropping. The product has passed extensive security evaluations and its patented design offers security functions that prevent all known methods of audio output channel attacks for remote eavesdropping even when target computer is infected or controlled by malicious code.

Computers connected to public networks and to the internet can be easily hacked and controlled remotely. Such computers having headphones connected are at risk of becoming an eavesdropping bug. Attacker can install a malicious code on the product that will turn the connected headphones elements into dynamic microphones. With proper audio driver modifications, this small signal may be amplified and filtered to enable picking up surrounding conversation. Then malicious code may easily compress the audio data and stream it over the internet to the interested remote attacker. The attacker reconstructs the audio signal, enhance it if needed and analyze it to recover valuable classified information. Such attack can exist while the user is completely unaware and it can even run undetectable by anti-virus and intrusion detection programs through the use of Zero Day Vulnerabilities.

One of the most common methods used to hack computer audio systems remotely is through the use of RAT (Remote Access Trojan). With the use of RAT the remote attacker can modify the audio CODEC driver functionality and switch the microphone input to the headphones or line-out jack. To prevent all this, there is a need for an efficient analog audio diode that can block all usable signals from the headphones to the computer.

  • Analogue Audio Data Diode
    Preventing audio stream from headphones flowing back to the computer audio jack. The only effective mean to protect from remote eavesdropping through connected headphones configured as microphone

  • Crystal clear audio quality
    The HSA210 uses active diode circuitry to assure that audio passing in the right direction is not distorted or attenuated. Security features does not negatively affect audio quality

  • Crossed installation detection
    The HSA210 can detect and prevent an attempt to connect it to the microphone by the user or through audio CODEC driver manipulation

  • Active anti-tampering
    Battery backed active anti-tampering system prevents in-transit tampering and enables full trust in the supplied product

  • No USB interface
    Preventing the need to change existing audio equipment. Also preventing the use of unsecure USB audio

  • Highest security by design
    The HSA210 is world’s first and only Common Criteria EAL 4+ (pending) audio security device. There is no other effective solution to prevent audio attacks in the markets today

  • Easy integration
    The HSA210 supports wide range of security products from HSL and from other vendors including Secure KVM switches, matrix, Secure KM etc.

HSA210 – Secure Headphone Diode 

No. of Computers

  • 1


  • 1 x USB Type-A to connect to computer
  • 1 x 3.5mm stereo jack for headphones output:
  • Supports 4-64 Ohm headsets
  • Can drive 0.25W per channel into 8 Ohm load
  • Support audio output into higher impedance devices such as amplified speakers

Controls and indications

  • Self-Test push-button with
  • LED for self-test (green) and tampering indications (red).

Security Features

  • Independent/isolated microcontroller
  • Analog Audio Data Diode circuitry to prevent the use of headphones as dynamic microphone
  • Detection of crossed connection of plug inserted into a microphone jack or headphones jack with changed role
  • Holographic tampering-evident labels
  • Active battery backed anti-tampering system to prevent physical tampering

Audio Features

  • Excellent flat audio response curve
  • Frequency response: 100-20,000Hz
  • Diode reverse-flow attenuation:  32 ± 4dB
  • S/N ratio: More than 52dB

Audio Cards Supported

  • All AC’97 CODECs on-board or cards
  • HD Audio CODECs
  • Note: Professional PCI Cards and multi-channel sound cards are not supported

Computer Ports

  • 1 x 3.5mm audio stereo plug for headphones or line output
  • 1 x USB Type-B


  • 55 (W) x 96 (D) x 21 (H) mm / 2.15 (W) x 3.77 (D) x 0.83 (H) inch.


  • 0.1 Kg. (0.2 lbs.).


  • Yellow tip DC power jack 5V DC, 0.2A (maximum)
  • Wall-mounted power supply 90-240VAC input

Operating Temperature

  • 0ºC to 40ºC (32ºF to 104ºF);

Storage Temperature

  • -20ºC to 60ºC (-4ºF to 140ºF)


  • Operating – 20 to 80% non-condensing;
  • Storage – 10 to 90% non-condensing


  • 0 to 10,000 ft


  • CE, UL and cUL, Safety BSEN60950 / EN60950

Product life-cycle

  • 10 years


  • 2 Years
  Specification Sheets File Size Date
HSA210 Secure Headphone Diode Datasheet

HSA210 Secure Headphone Diode Datasheet

431 KB 24 Feb, 2015

HSA210 – Secure Headphone Diode, Audio Output only, active anti-tampering, Silver, EU Power       

HSA210 – Secure Headphone Diode, Audio Output only, active anti-tampering, Silver, UK Power  

HSA210 – Secure Headphone Diode, Audio Output only, active anti-tampering, Silver, US Power              


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