How DES and 3DES work
Main Body:
What is the history of DES, and why is s-DES studied?
How does DES and 3DES work? Provide an example of each.
Explain the following ingredients that decide the algorithm in the Fiestel cipher:
Block size Key size
Subkey generation
Round function
Fast software encryption/decryption
Ease of Analysis
Conclusion
Sample Solution
DES (Data Encryption Standard) is a symmetric-key encryption algorithm that was developed by IBM in the 1970s and has since been used as one of the most widely accepted standards for secure data transmission. DES uses a 56 bit key to encrypt a message and then transmit it over an insecure network. To ensure maximum security, only the sender and receiver should know this key; otherwise, anyone can intercept or decode the message without authorization. DES utilizes what is called a Feistel cipher structure which separates each block of data into two halves before running it through multiple rounds of encryption using logic functions such as XOR and AND. This ensures that even if an attacker knows one half of the original message, they will still be unable to access its contents unless they know both halves—making it difficult for them to determine what data is being sent in between messages (“Cryptography Basics: Data Encryption Standard (DES)”). Although efficient, due to technological advancements like faster computers and better computing power, DES has become increasingly vulnerable to brute force attacks —where an attacker could guess all possible keys until finding the right one . To counter this , improved versions such as 3DES were developed which use three separate 56 bit keys instead of just one (Rajan & Rao). This tripled encryption process provides greater protection against brute force attacks since hackers would now need to go through three times more combinations in order to decrypt any information successfully .. To illustrate how DES works let us consider an example where Bob wants to send Alice a secret message “I Love You” . He first encodes his message into binary code —01001001 00111000 01101110 01100111 001110 1 10001001—and then uses his 56 bit key 00001111 11110000 11001100 11000011 11001000 11100010 11100011 10101010 on each 8 bit block using algorithms like XOR in order to transform it into something unrecognizable like - 0xF7ADEDC8D2A03DB9 . Finally , he sends out this ciphertextto Alice who runs her own version of the same algorithm with her own key on each 8 bits — resulting in retrieving back our original binary code iLoveYou.
eople that were Jewish or helped hide Jews were put in concentration camps and were forced to do labor like cooking, making tools, making clothing, and various other tasks. Then they were assigned barracks which, is where you sleep. Some camps were like regular summer camps, with a school, and just a single wire fence. But other concentration camps had maximum security, and were a lot more strict as in what you can and can’t do. If I were at one of these camps I would escape at night so no one could see me, then send my parents a letter and hope they didn’t get killed if the Germans found out I escaped.