Summary of Cryptography Motivation

Cryptography involves techniques like the Caesar Cipher and Vigenére Cipher, which encrypt messages by shifting letters. The Caesar Cipher uses a fixed shift, while the Vigenére Cipher uses a key with multiple shifts. Breaking these ciphers relies on frequency analysis, where the frequency of each letter in the encrypted message is compared to typical frequencies in natural language. For example, in English, 'e' is the most common letter. By assuming the most frequent letter in the encrypted message corresponds to 'e', we can attempt decryption. If the decrypted message doesn't make sense, we try the next most common letter. Writing a program to automate this process requires counting the frequency of each letter and identifying the highest count. Instead of writing cumbersome code with many parameters and repetitive conditions, we can use arrays to simplify and generalize the process.

Key Points

• Caesar Cipher: Shifts each letter by a fixed amount.
• Vigenére Cipher: Uses a key with multiple shift amounts.
• Frequency Analysis: Used to break ciphers by comparing letter frequencies in the encrypted message to typical frequencies in natural language.
• Programming Approach: Counting letter frequencies and identifying the highest count can be done more efficiently with arrays rather than numerous parameters and repetitive code.

Example Table