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HC-3300   Cryptovox
Secure Crypto Phone

CRYPTOVOX HC-3300 is a secure telephone set with digital speech encryption, developed in the early 1990s by Crypto AG (Hagelin) in Zug (Switzerland). It is suitable for analogue PSTN phone lines, and encrypts voice, data and facsimile traffic. A smart-card is used for key distribution.

The HC-3300 is housed in a rather heavy fully TEMPEST shielded die-cast aluminium enclosure. It has a double key pad with 12 keys each. The rightmost keypad is identical to that of a regular phone. It has the numbers 0-9 plus * and #.

All of the special features are controlled via the keypad on the left. The unit interacts with the user via a simple LCD display that is placed in the black section at the centre. Two LEDs to the right of the display show whether the phone is in plain (red) or crypto (green) mode. A valid key card should be inserted in a slot at the right.
HC-3300 crypto phone

Secure speech conversations are possible in full-duplex at 2400, 4800 and 9600 baud data rates, depending on the quality of the telephone line. In addition, half-duplex calls are possible at 2400 and 4800 baud. Secure group calls are possible at 2400 baud only. Data and facsimile messages can be sent and received at the same rates, with V.32, V.27 ter and V.22 bis [1].

The HC-3300 can hold 30 communication keys, 3 broadcast keys, 1 structure key and 1 Key Transportation Key (KTK). Each key is 128 bits long, allowing more that 1038 possible keys. It has a key stream period of more than 1028 years.

In 1999, the HC-3300 was still in use by the United Nations (UN) alongside the HC-4220 fax encryptor for the encryption of speech and data via land lines [2]. Apparently, neither the HC-3300 nor the HC-4220 were suitable for communication via HF (radio) or satellite. For a long time, the HC-3300 has been very popular within the governments of some South-American countries such as Mexico and Argentina, until they were decomissioned around 2010.

HC-3300 crypto phone Interior Close-up of the processor and the line interface Card reader
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HC-3300 crypto phone
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Close-up of the processor and the line interface
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Card reader

The image on the right shows the interior of the HC-3300 after removing the top cover. Several PCBs are visible, such as the main processor, the line interface, the interface to the contol panel and the card reader at the bottom right.

All cryptographic components are hidden in a metal enclosure below the main PCBs. Images of the crypto unit will be published on this page as and when they become available.
Close-up of the processor and the line interface

Help required
At present we don't know the operating procedure of this phone, but it seems likely that it can not be operated without a valid key (card) installed. Generation of such keys is usually done by means of a Key Management Center (KMC). To date, we have not found a way to enter the key manually. If you can provide more information or a user manual, please contact us.

  1. Crypto AG, Company brochure, Crypto Products
    1992. 8 pages.
  1. Jane's Military Communications, HC-3300 digitally ciphered telephone
    Date unknown. 1

  2. SHIRBRIG, Lessons Learned
    Multinational Standby High Readiness Brigade for United Nations Operations. 1 June 2009.
  1. Pages no longer available from the Jane's website in 2017.

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Crypto Museum. Created: Sunday 21 August 2011. Last changed: Saturday, 24 February 2018 - 10:39 CET.
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