The combination of what two processes increases the security of the resultant cipher text?

The combination of substitution and transposition enhances the security of cipher text by utilizing two distinct methods to obfuscate the original data.

Substitution replaces characters or bits in the plaintext with other characters or bits according to a defined system, making it difficult for an unauthorized party to deduce the original message just by analyzing the substituted values. This process effectively alters the appearance of the plaintext, creating a level of complexity that aids in protecting sensitive information.

Transposition, on the other hand, rearranges the order of characters or bits without altering their values. This means that while the components of the message are still present, their alignment and placement are altered, adding another layer of confusion to the data. When the output of the substitution is then subject to transposition, the result is a cipher text that has both scrambled values and altered order, making unauthorized decryption even more challenging.

Using substitution alone may offer a certain level of protection, but when combined with transposition, the security is significantly increased. This dual-layer approach means that even if an attacker were to analyze the cipher text, the chances of successfully retrieving the original data without knowledge of both methods used is extremely low. It provides a robust method for securing sensitive information against potential cryptanalysis attacks.