Sunday, July 4, 2021

CTR Mode | Counter Mode | Mode of Block Cipher | Application of Counter Mode

 

Counter Mode (CTR Mode)

   This mode is similar to OFB with the difference is that it uses counters or sequence number as input to the algorithm. There is no chaining process is done as shown in figure.

       We put a constant value as initial value of counter which will be of same size as that of a plaintext block. In counter mode, the counter is encrypted and then XORed with the plain text to cipher text.

 

Figure : Encryption Process

    During decryption process same counter is used which was encrypted earlier and later XORed with cipher text to get the original plain text as shown in figure.

 

Figure : Decryption Process

   Use of counter mode is block oriented transmission, where application needs high speed.


To learn more about Counter Mode, watch below video



Video : Counter Mode

Watch more videos click here.


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