Explanation:
As stated in the official CCSE Courseware, “A hash function is a one-way mathematical function that maps variable values into smaller values of a fixed length” The size of the message is made smaller in order to ensure maximum network performance. The shorter the message, the less computation required, and the better the performance. The result of the hash function, known as a message digest, is much smaller than the original message, but unique to it. If any changes to a message occur, the message digest will be different, indicating that the message has been altered. See Page 7.7 of CCSE NG Official Courseware. (VPN1-FW1 Management II NG FP-1).

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