1 Data Encryption Standard (DES) An example of secret key (i.e., symmetric) encryption system Note: These figures are meant to help illustrating a few.

Slides:

Advertisements

Similar presentations

6.1.2 Overview DES is a block cipher, as shown in Figure 6.1.

Advertisements

6.1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 2 Data Encryption Standard (DES)

1 CIS 5371 Cryptography 5b. Pseudorandom Objects in Practice Block Ciphers.

Cryptography and Network Security Chapter 3

Rachana Y. Patil 1 Data Encryption Standard (DES) (DES)

Data Encryption Standard (DES)

Symmetric Encryption Example: DES Weichao Wang. 2 Overview of the DES A block cipher: – encrypts blocks of 64 bits using a 64 bit key – outputs 64 bits.

DES 1 Data Encryption Standard DES 2 Data Encryption Standard  DES developed in 1970’s  Based on IBM Lucifer cipher  U.S. government standard  DES.

McGraw-Hill©The McGraw-Hill Companies, Inc., Security PART VII.

1 Day 04- Cryptography Acknowledgements to Dr. Ola Flygt of Växjö University, Sweden for providing the original slides.

Introduction to Symmetric Block Cipher Jing Deng Based on Prof. Rick Han’s Lecture Slides Dr. Andreas Steffen’s Security Tutorial.

Lecture 23 Symmetric Encryption

CSE 651: Introduction to Network Security

ECE454/CS594 Computer and Network Security Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2011.

Data Encryption Standard (DES). Symmetric Cryptography  C = E(P,K)  P = D(C,K)  Requirements  Given C, the only way to obtain P should be with  the.

The Digital Encryption Standard CSCI 5857: Encoding and Encryption.

Chapter 12 Cryptography Explained. Search Problems Specified by an algorithm C Two inputs ◦ I is the instance. ◦ S is the solution. ◦ Must complete in.

CSCI 5857: Encoding and Encryption

5.1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 5 Introduction to Modern Symmetric-key Ciphers.

Chapter 2 – Elementary Cryptography  Concepts of encryption  Cryptanalysis  Symmetric (secret key) Encryption (DES & AES)(DES & AES)  Asymmetric (public.

Network Security Lecture 14 Presented by: Dr. Munam Ali Shah.

Chapter 20 Symmetric Encryption and Message Confidentiality.

TE/CS 536 Network Security Spring 2006 – Lectures 6&7 Secret Key Cryptography.

Chapter 20 Symmetric Encryption and Message Confidentiality.

30.1 Chapter 30 Cryptography Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Feistel Cipher Structure

Cracking DES Cryptosystem A cryptosystem is made of these parts: Two parties who want to communicate over an insecure channel An encryption algorithm that.

Classical Encryption techniques

Elementary Cryptography  Concepts of encryption  Symmetric (secret key) Encryption (DES & AES)(DES & AES)  Asymmetric (public key) Encryption (RSA)(RSA)

Data Encryption Standard (DES) © 2000 Gregory Kesden.

Classical &ontemporyryptology 1 Block Cipher Today’s most widely used ciphers are in the class of Block Ciphers Today’s most widely used ciphers are in.

DES Algorithm Data Encryption Standard. DES Features Block cipher, 64 bits per block 64-bit key, with only 56 bits effective ECB mode and CBC mode.

Stream Ciphers and Block Ciphers A stream cipher is one that encrypts a digital data stream one bit or one byte at a time. Examples of classical stream.

1 University of Palestine Information Security Principles ITGD 2202 Ms. Eman Alajrami 2 nd Semester

1 CIS 5371 Cryptography 5a. Pseudorandom Objects in Practice Block Ciphers B ased on: Jonathan Katz and Yehuda Lindell Introduction to Modern Cryptography.

AES Advanced Encryption Standard. Requirements for AES AES had to be a private key algorithm. It had to use a shared secret key. It had to support the.

Permuted Choice #

30.1 Chapter 30 Cryptography Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Introduction to Modern Symmetric-key Ciphers

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter Thirteen Channel Coding and Encryption.

24-Nov-15Security Cryptography Cryptography is the science and art of transforming messages to make them secure and immune to attacks. It involves plaintext,

Chapter 3 Encryption Algorithms & Systems (Part D)

Lecture 23 Symmetric Encryption

1 Symmetric key cryptography: DES DES: Data Encryption Standard US encryption standard [NIST 1993] 56-bit symmetric key, 64 bit plaintext input How secure.

Lecture 3 Overview. Ciphers The intent of cryptography is to provide secrecy to messages and data Substitutions – ‘hide’ letters of plaintext Transposition.

K. Salah1 Cryptography Module I. K. Salah2 Cryptographic Protocols  Messages should be transmitted to destination  Only the recipient should see it.

DATA & COMPUTER SECURITY (CSNB414) MODULE 3 MODERN SYMMETRIC ENCRYPTION.

5.1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 5 Introduction to Modern Symmetric-key Ciphers.

Lecture 4 Overview. Data Encryption Standard Combination of substitution and transposition – Repeated for 16 cycles – Provides confusion and diffusion.

Lecture 3 Overview. Ciphers The intent of cryptography is to provide secrecy to messages and data Substitutions – ‘hide’ letters of plaintext Transposition.

Lecture 4 Overview. Data Encryption Standard Combination of substitution and transposition – Repeated for 16 cycles – Provides confusion and diffusion.

Computer Science and Engineering Computer System Security CSE 5339/7339 Lecture 7 September 9, 2004.

Module :MA3036NI Symmetric Encryption -3 Lecture Week 4.

Block Ciphers and the Data Encryption Standard. Modern Block Ciphers  One of the most widely used types of cryptographic algorithms  Used in symmetric.

CPIT 425 Chapter Three: Symmetric Key Cryptography.

Information and Network Security Lecture 2 Dr. Hadi AL Saadi.

Information and Computer Security CPIS 312 Lab 6 & 7 1 TRIGUI Mohamed Salim Symmetric key cryptography.

@Yuan Xue Announcement Project Release Team forming Homework 1 will be released next Tuesday.

Lecture 4 Data Encryption Standard (DES) Dr. Nermin Hamza

CS480 Cryptography and Information Security

Provides Confidentiality

- Stream Cipher and Block Cipher - Confusion & Diffusion

Networks and Communication Systems Department

Introduction to Modern Symmetric-key Ciphers

DES Examples Chater#3 DES.

Computer Security IT423 Semester II

DES (Data Encryption Standard)

DATA ENCRYPTION STANDARD (DES)

Presentation transcript:

1 Data Encryption Standard (DES) An example of secret key (i.e., symmetric) encryption system Note: These figures are meant to help illustrating a few points. (The goal is to save time in reproducing large tables & figures on the board and coping them in the notebooks.) There are other important points covered in class that are not given in the following slides. Please refer to the lectures and the text book for details.

2 DES is a complex combination of substitution and transposition (CONFUSION and DIFFUSION) repeatedly applied, one on top of the other, for total of 16 cycles Cycle 1 Cycle 2 Cycle 16

3 One DES cycle (total 16) Slide 5 Slide 6 Slide 7 & 8 Slide 9 Initial permutation 16 cycles Inverse initial permutation Combines permutation and substitution, including key

4 Permutation General idea: rearrange the characters Example in class: Columnar transposition Write the plain text in 5 columns MARYL ANDWV UGAME ISTON IGHTX Cipher text - read by column mauii angsg rdath ywmot lvenx

5 Expansion permutation General idea: rearrange the bits & repeat certain bits Pattern used in each cycle of DES to expand the right block from 32 bits to 48 bits

6 Permuted Choice General idea: rearrange the bits & omit certain bits Pattern used in each cycle of DES to shorten the sifted key from 56 bits to 48 bits

7 S-Box Substitution, Choice Start with 48 bits ( ) Divide them in 8 blocks, each long 6 bits For each block using the look-up table on the next slide produce 4 bits End result is 8 blocks, each long 4 bits (total 32 bits output from the S-box) Output from each block 4 bits Input in each block 6 bits See the example on the next slide

8 row 1 column 9 In block S 7 choose row 1, column 9 The output is 3, that is, 0011 binary (4 bits) Example: The input to block S 7 is (6 bits) S-Box look-up table & Example

9 P- box Permutation BitsGoes to position – – Straight permutation: Each input bit is moved to a new position in the output Rearrangement used in DES