In each group, 1 letter appears 5 times, 2 letters appear 4 times each, 4 letters appear 3 times each, 5 letters appear 2 times each, and 9 letters appear 1 time each. The transformation of the plaintext into the ciphertext has been carried out using one of the following methods, both illustrating a “segmentation and recombination” technique : (Hypothesis 1) The plaintext has first been enciphered (a) and then split into segments divided into two groups (b), adjusted to have the same letter frequency distribution shapes (c), and recombined with intermediary letters ‘W’ (d), (Hypothesis 2) The plaintext has first been split into segments divided into two groups (a), then each segment has been enciphered using a technique specific to its group (b); additionally, the groups have been…