Encryption. LEARNING OBJECTIVES: BY THE END OF THE LESSON YOU SHOULD KNOW. What encryption is and why it is important The basics of encryption techniques.

Slides:

Advertisements

Similar presentations

CLASSICAL ENCRYPTION TECHNIQUES

Advertisements

Using Cryptography to Secure Information. Overview Introduction to Cryptography Using Symmetric Encryption Using Hash Functions Using Public Key Encryption.

Cryptology Terminology and Early History. Cryptology Terms Cryptology –The science of concealing the meaning of messages and the discovery of the meaning.

Cryptology  Terminology  plaintext - text that is not encrypted.  ciphertext - the output of the encryption process.  key - the information required.

Creating Secret Messages. 2 Why do we need to keep things secret? Historically, secret messages were used in wars and battles For example, the Enigma.

Introduction to Cryptography and Security Mechanisms Dr Keith Martin McCrea

CYPHER INDEX n Introduction n Background n Demo INTRODUCTION n Cypher is a software toolkit designed to aid in the decryption of standard (historical)

CPSC CPSC 3730 Cryptography Chapter 2 Classical Encryption Techniques.

Chapter 13: Electronic Commerce and Information Security Invitation to Computer Science, C++ Version, Fourth Edition SP09: Contains security section (13.4)

Introduction to Cryptography

Cryptography Week-6.

History and Background Part 1: Basic Concepts and Monoalphabetic Substitution CSCI 5857: Encoding and Encryption.

Polyalphabetic Substitution Ciphers. First Steps Towards Complexity  If one alphabet is good, then two alphabets must be better!  By doubling the number.

Chapter 2 Basic Encryption and Decryption. csci5233 computer security & integrity 2 Encryption / Decryption encrypted transmission AB plaintext ciphertext.

Security in Computing Cryptography (Introduction) Derived from Greek words: ‘Kruptos’ (hidden) and ‘graphein’ (writing.

Introduction to Information Security Chapter II : Classical Ciphers.

Week 2 - Wednesday.  What did we talk about last time?  Encryption  Shift ciphers  Transposition ciphers.

CS110: Computers and the Internet Encryption and Certificates.

Section 2.1: Shift Ciphers and Modular Arithmetic The purpose of this section is to learn about modular arithmetic, which is one of the fundamental mathematical.

Cryptography Data communications and networks Momina Tariq: Ambreen Sohail: Data Communications and Networks.

Lec. 5 : History of Cryptologic Research II

Introduction to Cryptography

Day 18. Concepts Plaintext: the original message Ciphertext: the transformed message Encryption: transformation of plaintext into ciphertext Decryption:

Chapter 17 Security. Information Systems Cryptography Key Exchange Protocols Password Combinatorics Other Security Issues 12-2.

Section 2.1: Shift Ciphers and Modular Arithmetic Practice HW from Barr Textbook (not to hand in) p.66 # 1, 2, 3-6, 9-12, 13, 15.

CIT 380: Securing Computer SystemsSlide #1 CIT 380: Securing Computer Systems Classical Cryptography.

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

Symmetric-Key Cryptography

Module :MA3036NI Cryptography and Number Theory Lecture Week 3 Symmetric Encryption-2.

NET 311 Information Security

CSCI 5857: Encoding and Encryption

Abstract: Cryptology is a combination of the processes of keeping a message secret (cryptography) and trying to break the secrecy of that message (cryptoanalysis).

Classical Crypto By: Luong-Sorin VA, IMIT Dith Nimol, IMIT.

Data Security and Encryption (CSE348) 1. Lecture # 4 2.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Security.

Traditional Symmetric-Key Ciphers

Computer Security Cryptography. Cryptography Now and Before  In the past – mainly used for confidentiality  Today –Still used for confidentiality –Data.

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

CRYPTOGRAPHY. TOPICS OF SEMINAR Introduction & Related Terms Categories and Aspects of cryptography Model of Network Security Encryption Techniques Public.

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

Section 2.5 Polyaphabetic Substitutions

Computer Science and Engineering Computer System Security CSE 5339/7339 Lecture 3 August 26, 2004.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Security PART VII.

Section 2.3: Substitution Ciphers

Encryption CS110: Computer Science and the Internet.

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

Introduction to Cryptography Lecture 8. Polyalphabetic Substitutions Definition: Let be different substitution ciphers. Then to encrypt the message apply.

Vigenére Cipher Kimberly Chiffens & Maria Jannelli.

Network Security Lecture 13 Presented by: Dr. Munam Ali Shah.

Introduction to Cryptography Lecture 4. Caesar Cipher Gaius Julius Caesar (100 B.C.- 44 B.C.) General Politician Dictator of Rome Creator of Caesar Cipher.

1 Introduction CS 303 Algorithmic Number Theory and Cryptography Jeremy R. Johnson.

Substitution Ciphers Reference –Matt Bishop, Computer Security, Addison Wesley, 2003.

Lecture 2 Classical Cipher System SIMPLE SUBSTITUTION CIPHERS By: NOOR DHIA AL- SHAKARCHY

Computer Security By Rubel Biswas. Introduction History Terms & Definitions Symmetric and Asymmetric Attacks on Cryptosystems Outline.

Information Security CPIT 425 Instructor: Bashair Alrashed LAB1.

CS480 Cryptography and Information Security Huiping Guo Department of Computer Science California State University, Los Angeles 4. Traditional and Modern.

Substitution Ciphers.

Chapter 2 Basic Encryption and Decryption

Computer and Data Security 4th Class

Information and Computer Security CPIS 312 Lab 2

Topics discussed in this section: 30-2 SYMMETRIC-KEY CRYPTOGRAPHY Symmetric-key cryptography started thousands of years ago when people needed.

Topic 3: Data Encryption.

NET 311D Information Security

Simple Encryption- Lesson 5

Fun with Cryptography The Science of Secrecy.

Double Transpositions

Symmetric Encryption or conventional / private-key / single-key

NET 311D Information Security

Presentation transcript:

Encryption. LEARNING OBJECTIVES: BY THE END OF THE LESSON YOU SHOULD KNOW. What encryption is and why it is important The basics of encryption techniques How to encrypt a message using the Caesar cipher How to encrypt a message using the transposition cipher How to use frequency analysis to help decrypt ciphers

Encryption - Starter: Since you were so upset last week. Here is the quiz!! Please enter the link below to play the quiz regarding number systems.  Learning Objectives: By the end of the lesson you should know. What encryption is and why it is important The basics of encryption techniques How to encrypt a message using the Caesar cipher How to encrypt a message using the transposition cipher How to use frequency analysis to help decrypt ciphers

What is Encryption?:  It’s a process of scrambling information so it cannot be understood by anyone intercepting the data.  To decrypt it you need to know the encryption method and key used.Sender Data Receiver

Why is it important?:  Data is vulnerable  It could be personal information  It could be sensitive information  Networks and computers can be hacked

Encryption Basics:  How does it work?  By changing plaintext into ciphertext  Hello world  Cfzzn anwzx  Hello world  Decrypted by receiver by knowing the cipher method and using a key.

Caesar cipher.  Example of a shift cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ ABCDEFGHIJKLMNOPQRSTUVWXYZ

Caesar cipher.  Example of a shift cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ VWXYZABCDEFGHIJKLMNOPQRSTU An example of a monoalphabetic cipher. What is the key? Ans: 5

Caesar cipher.  Example of a substitution cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ ERNESTBEVIN

Caesar cipher.  Example of a substitution cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ ERNSTBVI

Caesar cipher.  Example of a substitution cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ ERNSTBVIACDFGHJKLMOPQUWXYZ ERNSTBVI What is the key? Ans:

Caesar cipher.  Another example of a substitution cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ ERNSTBVIACDFGHJKLMOPQUWXYZ ABCDEFGHIJKLMNOPQRSTUVWXYZ DQKWROTPJYNUBSIXCLAZGMVEFH An example of a polyalphabetic cipher. What is the key? Ans: a lookup table

Frequency analysis  Shift/substitution ciphers are easy to crack.  Done by analysing the frequency of characters.  Who can guess most frequent letter in English alphabet?  Ans: E

Transposition Cipher  Please watch this video tutorial. 

Plenary:  How did you get on with the task?  Was it too difficult/too easy?  Are you confident you have learnt the learning objectives?  Homework: Read through section 27 and complete tasks in AQA A level Computer Science for before next week lesson. And remember UPLOAD TO FRONTER!!!