The technique that involves rearranging the positions of characters in the plaintext to create ciphertext is known as a transposition cipher. In this encryption method, the actual characters in the plaintext remain unchanged; instead, their positions are altered according to a specific system or key. This results in a ciphertext that maintains the original character set but in a different order, making it more challenging for an unauthorized party to decipher the message without knowledge of the rearrangement method used.
Transposition ciphers are effective because by merely rearranging the characters, the cipher can make patterns in the plaintext less apparent, enhancing the cryptographic strength. This technique is typically used in conjunction with other forms of encryption to bolster security.
In contrast, substitution ciphers operate by replacing each character in the plaintext with another character, rather than rearranging their positions. Block ciphers and asymmetric ciphers are different types of encryption techniques that deal with larger blocks of data or make use of paired keys for encryption and decryption, but they do not specifically focus on rearranging characters.