Quiz Chapter 7

What is the message authentication code process why is it considered ‘good’?

Answer:

The message authentication code process is as follows:
  1. A key is generated by a key generation operation and is shared between the sender and the receiver.
  2. The sender takes the key (authentication key) and the message as input and outputs a tag; a cryptographic checksum depending on the key and the message as its output.
  3. The receiver then takes the message and the key and performs the same checksum. If the result matches the tag, the message has been verified.
The process is considered ‘good’ because the best method for forging the process is by guessing the 1 of 2n possibilities the tag could be, where n is the amount of bits long the tag is.

Topic revision: r2 - 2013-12-18 - JimSkon
 
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