A transposition cipher is a type of cipher that encrypts a document by rearranging the same characters to produce the ciphertext. A transposition cipher does not change the identity or frequency of the characters, but only their position. A transposition cipher can use various methods to permute the characters, such as writing them in a grid and reading them in a different order, or shifting them along a rail fence pattern. A transposition cipher is a simple and fast algorithm, but it can be easily broken by frequency analysis or anagramming. A transposition cipher is the type of cipher employed by Kevin in the above scenario, as he used a simple algorithm to encrypt the document that just rearranges the same characters to produce the ciphertext. Reference:

Transposition cipher - Wikipedia

Network Security: Transposition Cipher Techniques - Coding Streets

Network Defense Essentials (NDE) | Coursera - Module 4: Cryptography Techniques

Columnar Transposition Cipher - GeeksforGeeks