Fig. 1 shows a simple encryption algorithm for messages sent from a research boat. Each letter is replaced by the next letter in the alphabet. The alphabet ...
Question 1 Report
Fig. 1 shows a simple encryption algorithm for messages sent from a research boat. Each letter is replaced by the next letter in the alphabet. The alphabet wraps from Z to A. A receiving program reverses the process before it displays the original word. This method is weak encryption, but it is useful for demonstrating how an algorithm changes data using a fixed rule.
(a) Identify the encrypted letter for M. [1]
(b) Write the encrypted word for CAP. [1]
(c) State the original letter when the receiver changes D back by one. [1]
(d) Give the encrypted letter for Z. [1]
(e) Identify one reason this encryption is not secure for important data. [1]
Answer Details
(a) Shifting M forward by one letter gives N. [1]
(b) Encrypt each letter of CAP by shifting it one place: \(C\rightarrow D\), \(A\rightarrow B\), \(P\rightarrow Q\). The encrypted word is DBQ. [1]
(c) Reversing D by one letter gives C. [1]
(d) The alphabet wraps around, so Z encrypts to A. [1]
(e) This encryption is not secure for important data because the rule or key is easy to guess. [1] There are very few possible shifts, so an attacker can try them quickly.
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