When the soft key key "Crypto " is pressed, the two phones and the receiving phone automatically select a new 128 bit encryption. Some 1038 possible codes are possible. With termination of the call, the code is  deleted immediately. The code change is apart from the key length an important safety factor. 

Technical data:

• Speech transmission with GSM Half rate Vocoder
  
• Uses transparent data channel in the GSM asymmetrical algorithm (combination of Diffie Helmann and RSA) for code agreement with 1024 bits key length symmetrical algorithm with 128 bits key length communication 
  
• GSM to GSM communication GSM to ISDN
  
• The compressed voice signal is sent over the GSM data channel using the GSM half rate Vocoder. 
  
• The compressed data become with information error recognition and - correction completed and then encodes. Then they are provided with further information for the synchronisation of the receiving station and transmitted over the data channel. 
  
  
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