katkryptolog

 A fax with an encoder , model HC-4400-09 from the Swiss Company Crypto AG , was placed at Ministry of Foreign Affairs of the Slovak Republic (SR) and abroad at the representative offices of the Slovak Republic. It was used to encrypt and transfer copies of documents using the regular telephone network. The electronic device was compatible with any fax machine or personal computer. It was in the service as a fax server, did not have any restrictions on standard devices, with an error correction mode, automatic protocol adaptation, a security module resistant to unauthorised manipulation, automatic or manual key selection, for protection against forgery, for generating and encrypting keys, a program for managing keys, protected database, speed from 2400 to 14400 b/s. Installation and  operation of the fax machine was simple. Cryptodevice - a fax with encoder - model HC-4400-09  The device was manufactured in the 1990s by the Swiss company Crypto AG , which specialised in...

How the Czechoslovak secret service ŠtB breaks the encryption machine Gretag TC 803 at the Spanish embassy in Prague: https://www.info.cz/zpravodajstvi/cesko/akce-sumperk?odemknout=YAYLEWR8KH Detailed description of the encryption machine  Gretag TC 803 : https://www.cryptomuseum.com/crypto/gretag/803/index.htm Picture of the cipher machine's daily key block   "...Another break-in at the embassy took place on June 27, 1980. In this case, the State Security encountered a problem that it could not deal with. The Spanish started using the Gretag TC 803 encryption machine. ... Daily slips of paper with an encryption key were inserted into it. These were stored in a safe and bound with bookbinding cloth on three sides and in the middle. The canvas thus formed a kind of letter E with four arms. Between the canvas arms were perforated slips of metal foil that were inserted into the encryption machine. One part was designated for each day. Used and unused keys were shredded the...