1. Subscribers choose the encryption system (e.g., the Caesar cipher with a shift by n positions).
2. Subscribers agreed on the encryption key.
3. Subscriber # 1 encrypts the original message, using the key, by the selected method and gets an encrypted message.
4. The encrypted message is sent to the subscriber No. 2.
5. Subscriber # 2 decrypts the encrypted message using the key and receives the open message.
This protocol is quite simple, but it can really be used in practice. Cryptographic protocols can be simple or complex depending on the destination. …show more content…
In many cases the attack may be directed not on the encryption algorithm but on the protocol. Therefore, even the presence of absolutely reliable encryption algorithm does not guarantee full security to the subscribers of the communication system. Known cases, when cryptographic protocols applied in practice, contain flaws that allow the fraud of the parties involved or the decryption by an active intruder. Of course, cryptographic protocols should not allow such opportunities for the offenders. That's why currently, cryptographic protocols are the subject of careful analysis by