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Data Encryption Standard (DES)

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DES - Data Encryption Standard | Data Encryption Standard In Cryptography | Simp

Jul 25, 2021

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In this presentation on DES - Data Encryption Standard, we learn about the origin of the encryption algorithm while understanding the importance of Feistel Ciphers. The steps for encryption and decryption are explained in detail, and we also read about the future of the Data Encryption Standard in cryptography. In the end, we take a look at a live example to further highlight the characteristics of DES encryption.<br><br>Learn more at https://www.simplilearn.com/cyber-security-expert-master-program-training-course

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Today’s Agenda What Is DES? Origin of DES Feistel Ciphers How DES Works Future of DES Live Example

What Is DES?

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What Is DES? • Stands for Data Encryption Standard • Symmetric-Key algorithm using block-by-block encryption • Block size is 64 bits and key size is 48 bits • Follows the Feistel Cipher structure Block 1 Block 2 Block n Plaintext Broken down to 64-bit blocks

Origin of DES

Feistel Ciphers

Feistel Ciphers • Block Cipher that is used as a structure for encryption algorithms • Uses substitution and permutation alternately • Based on Shannon Structure from 1945 • Developed by Horst Feistel • Reversing the process can decrypt ciphertext back to plaintext

Feistel Ciphers Plaintext (64-bit) Left Half(32-bit) Right Half(32-bit) + XOR Operation F Encryption Key used here New Left Half New Right Half

Round Function One Half (32-bit) Expansion Box + 48-bit Text Kn 48-bit Key 48-bit Output

Round Function 48-bit Output S-Box XOR’d with the other half of plaintext 32-bit Output

Structure Guidelines • Block size should be a compromise between size and speed

Structure Guidelines • Block size should be a compromise between size and speed • Key size is directly proportional to strength of encryption

Structure Guidelines • Block size should be a compromise between size and speed • Key size is directly proportional to strength of encryption • Higher the number of rounds, tougher it is to crack

Structure Guidelines • Block size should be a compromise between size and speed • Key size is directly proportional to strength of encryption • Higher the number of rounds, tougher it is to crack • Round function should be complex

Structure Guidelines • Block size should be a compromise between size and speed • Key size is directly proportional to strength of encryption • Higher the number of rounds, tougher it is to crack • Round function should be complex • Speed is essential to handle large amounts of data

How DES Works

How DES Works – Key Generation 64-bit Plaintext Initial Permutation K0 Round 1 48-bit key K1 56-bit Cipher Key Round 2 Round-key Generator 48-bit key K15 Round 16 48-bit key Final Permutation 64-bit Ciphertext

How DES Works - Decryption 64-bit Ciphertext Final Permutation K15 Round 16 48-bit key 56-bit Cipher Key K1 Round-key Generator Round 2 48-bit key K0 Round 1 48-bit key 64-bit Plaintext Initial Permutation

Modes of Operation Electronic Codebook Cipher Block Chaining DES Cipher Feedback Block Output Feedback Counter Method

Future of DES

Future of DES • Replaced by AES in 2002 as the world standard for encryption • 56-bit key size easily broken by new generation computers • Withdrawn support for official purposes in 2005 • Triple-DES still allowed for important data till 2030

Live Example

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Performance Analysis of Data Encryption Standard DES

Information security is becoming much more important in data storage and transmission with the fast progression of digital data exchange in electronic way. Cryptography has come up as a solution which plays a vital role in information security system against malicious attacks. The cryptography is most important aspect of communications security and becoming an important building block for computer security. This security mechanism uses some algorithms to scramble data into unreadable text which can be only being decoded or decrypted by party those possesses the associated key. To protect sent messages that some of the most commonly used cryptography methods with private key based algorithm are LOKI 89, 91, 97 , DES, triple DES, AES, Blowfish, etc. These algorithms also include several computational issues as well as the analysis of DES algorithm. The main features that specify and differentiate one algorithm from another are the ability to the speed of encryption and decryption of the input plain text. This paper analyzes the private key based algorithm DES and LOKI91 by computing index of coincidence IC and time efficiency. Thida Soe | Soe Soe Mon | Khin Aye Thu "Performance Analysis of Data Encryption Standard (DES)" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26650.pdf Paper URL: https://www.ijtsrd.com/computer-science/computer-security/26650/performance-analysis-of-data-encryption-standard-des/thida-soe

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• Preferences

DATA ENCRYPTION STANDARD - PowerPoint PPT Presentation

DATA ENCRYPTION STANDARD

Des is an encryption block cipher that encrypts data in 64-bit blocks. ... official description, 'data encryption standard', published january 15, 1977. ... – powerpoint ppt presentation.

• Shirley Ann Fogarty
• Pat OCallaghan
• Karen Waters
• Eoin Cosgrave
• DES was developed by IBM and was endorsed by the US government in 1977 as an official standard.
• DES is an encryption block cipher that encrypts data in 64-bit blocks.
• When in use, both the receiver and the sender must use the same key for encryption and decryption.
• Main Components Algorithm and key
• 64 - bit block of plaintext enters algorithm.
• Split in half, combined with the key and 16 identical rounds are performed on it.
• 64-bit block of ciphertext is produced from the algorithm.
• National Bureau of Standards (NBS) wanted a program to protect computer and communications data .
• IBM developed an algorithm from an old algorithm called Lucifer.
• The response from the public was good yet wary due to the involvement of the NSA.
• Official description, Data Encryption Standard, published January 15, 1977.
• DES is reviewed every 5 years.
• To this day no suitable replacement algorithm has been found.
• DES is expected to have a backdoor in the algorithm.
• There are 64 weak keys and when used for the initial keys can cause security problems.
• There are rumors that a computer has been built which can crack it in 3 hours.
• Multiple DESThe algorithm is applied several times
• Tuchman developed a method known as Triple Encryption with Two Keys (EDE mode)
• Doubling the block length128 vs. 64 bit block pros and cons
• DES The algorithm of choice
• Users include IBM, Motorola and General Electric
• DES based products include mobile radio units and encryption boxes for use with microwave, satellite and other types of communications
• Several cryptographers have brought lawsuits against the U.S Government.
• Between the 1970s and 1990s NSA threatened people with prosecution if they published certain scientific papers
• 1996 saw a decision that no attempts should be made to regulate publications in books or any form of paper .
• On 1/7/98, IBM submitted a new encryption algorithm to NIST for consideration as the AES
• It has a 128-bit key, and can be used in hardware, software and in bandwidth-constrained applications i.e smart cards.
• Although DES is still a strong encryption algorithm NIST is said to be preparing for its eventual replacement.

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