Of the two processes used in symmetric key cryptography, which involves swapping blocks of the text?

In symmetric key cryptography, the process that involves swapping blocks of text is known as transposition. This method rearranges the positions of the elements within the plaintext to create ciphertext without altering the actual characters. The primary objective of transposition is to shuffle the data, making it unreadable without the key that specifies how the original order can be restored.

In contrast, encryption refers broadly to the process of converting plaintext into ciphertext using a specific algorithm and key, while decryption is the reverse process of transforming ciphertext back into plaintext. Substitution, on the other hand, involves replacing elements of the plaintext with other symbols to conceal the original message but does not focus specifically on swapping or rearranging positions.

The use of transposition is pivotal in creating complex relationships between the characters in the text, ensuring that even if portions of the ciphertext are known, the original text is still challenging to decipher without the corresponding key.