Cryptography

In: Computers and Technology

Submitted By alagurajavel
Words 1831
Pages 8
Prologue:
Cryptography is an excellent art/science of protecting data from unwanted intruders by transforming the data to an unreadable format which can be brought back to the original form only by those who are authenticated to do so. This system depends vastly on a principle of key usage and is the basic underlying principle of network security. A detailed technical discussion of cryptography ,particularly from a network’s stand point provides a compelling and an up to date examination of the political and the social issues that are now inextricably intertwined with cryptography. A complete discussion of cryptography itself requires a complete book and so we touch on only the essential aspects of cryptography. It is now high time to introduce Alice and Bob who are essentially the widely accepted persons for a discussion on networks as communicators. Also ,the third party Trudy ,the intruder also has a wide role to play in hacking the discussion of the two. So the whole thread would hang about these three and the ways there adhere to secure and hack the data that is transmitted.

A First look on Terminologies
Now its high time to know the basic terminologies of Cryptography. Firstly the text that we type in the human understandable format is called as the Plain Text. The plain text is then converted to a generally incomprehensive form called as the Cipher text using a technique called Encryption which usually does this, and the cipher is transmitted. Precisely a particular encoding way is chosen by a series of letters or numbers for the encryption and the decryption called as the Key. The cipher when reaches the receiver is converted back to the plain text form by the usage of a key and the technique called as Decryption or Deciphering. Ciphering and deciphering follow specified formats making them a privilege to be used by the definitions of…...

Similar Documents

Cryptography Methods

...Unit 3 Discussion 1: Access Control Models 1. Select an access control model that best prevents unauthorized access for each of the five scenarios given in the worksheet 2. Which types of logical access controls should be used in each scenario? Justify your recommendations. Scenario 1. - Discretionary access controls I s a small company consisting of 12 computers only DAC allows each user to control access to their own data and is typically the default access control mechanism for most desktop operating systems. Scenario 2.-Role-based access control Because RBAC is based on a user's job function within the organization to which the computer system belongs. Scenario 3.-Mandatory access controls Because how big is the company MAC takes a hierarchical approach to controlling access to resources. Under a MAC enforced environment access to all resource objects (such as data files) is controlled by settings defined by the system administrator. As such, all access to resource objects is strictly controlled by the operating system based on system administrator configured settings. Mandatory Access Control the operating system checks the user's classification and categories and compares them to the properties of the object's security label. Scenario 4.- Mandatory access control The design of MAC was defined, and is primarily used by the government. Scenario 5.- Mandatory access control Because all access to resource objects is strictly controlled by the...

Words: 452 - Pages: 2

Cryptography

...Prologue: Cryptography is an excellent art/science of protecting data from unwanted intruders by transforming the data to an unreadable format which can be brought back to the original form only by those who are authenticated to do so. This system depends vastly on a principle of key usage and is the basic underlying principle of network security. A detailed technical discussion of cryptography ,particularly from a network’s stand point provides a compelling and an up to date examination of the political and the social issues that are now inextricably intertwined with cryptography. A complete discussion of cryptography itself requires a complete book and so we touch on only the essential aspects of cryptography. It is now high time to introduce Alice and Bob who are essentially the widely accepted persons for a discussion on networks as communicators. Also ,the third party Trudy ,the intruder also has a wide role to play in hacking the discussion of the two. So the whole thread would hang about these three and the ways there adhere to secure and hack the data that is transmitted. A First look on Terminologies Now its high time to know the basic terminologies of Cryptography. Firstly the text that we type in the human understandable format is called as the Plain Text. The plain text is then converted to a generally incomprehensive form called as the Cipher text using a technique called Encryption which usually does this, and the cipher is transmitted...

Words: 1831 - Pages: 8

Data Cryptography

...Scams of the day!!! © 2012 Jones and Bartlett Learning, LLC www.jblearning.com Fundamentals of Information Systems Security © 2012 Jones and Bartlett Learning, LLC www.jblearning.com Page 2 Fundamentals of Information Systems Security © 2012 Jones and Bartlett Learning, LLC www.jblearning.com Page 3 On to today’s lesson © 2012 Jones and Bartlett Learning, LLC www.jblearning.com FIRST OF ALL… §  Let me clear up a misconception §  RSA public/private key encryption is THE leader, in terms of security. For all practical purposes, it is impossible to crack a RSA algorithm. §  PGP (Pretty Good Privacy) is probably the best implementation of RSA. It is now owned by Symantec. §  Other free products (which do not tightly integrate into email, for example) are available §  Understand that PKI is NOT the same thing as public key encryption Fundamentals of Information Systems Security © 2012 Jones and Bartlett Learning, LLC www.jblearning.com Page 5 Fundamentals of Information Systems Security © 2012 Jones and Bartlett Learning, LLC www.jblearning.com Page 6 Public Key Infrastructure (PKI) is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates. In cryptography, a PKI is an arrangement that binds public keys with respective user identities by means of a certificate authority (CA). The user identity must be unique within each CA domain. The...

Words: 1799 - Pages: 8

Cryptography

...EC6020 – ARSITEKTUR KOMPUTER LANJUT TUGAS – 4 CHAPTER 5 BUS, CACHE AND SHARED MEMORY SOAL-SOAL TENTANG ORGANISASI-ORGANISASI CACHE MEMORY (CACHE MEMORY ORGANIZATIONS) ARWIN NIM. 232 06 008 MAGISTER TEKNIK ELEKTRO SEKOLAH TINGGI ELEKTRONIKA DAN INFORMATIKA INSTITUT TEKNOLOGI BANDUNG 2006 1 Problem 5.8 – The main memory of a computer is organized as 64 blocks with a block size of eight (8) words. The cache has eight (8) block frames. In parts (a) through (d), show the mapping from the numbered blocks in main memory to the block frames in the cache. Draw all lines showing the mappings as clearly as possible. a. Show the direct mapping and the address bits that identify the tag field, the block number, and the word number. b. Show the fully associative mapping and the address bits that identify the tag field and the word number. c. Show the two-way set-associativity mapping and the address bits that identify the tag field, the set number, and the word number. d. Show the sector mapping with four blocks per sector and the address bits that identify the sector number, the block number, and the word number Answer : From the above statement, we get the memory and cache configuration information to calculate the identification bits and the addressing scheme. They are : Main memory has 64 blocks → n = 64 Cache memory has 8 block frames → Block size is 8 words → b = 8 ↔ s = 6 because n = 2 s m = 8 ↔ r = 3 because m = 2r ↔ w = 3...

Words: 1195 - Pages: 5

Biometric Uid Authentication Using Visual Cryptography

...[1] A.K. Jain and A. Ross, “Biometrics: a tool for information security”, IEEE Transaction on Information Forensics and Security, vol. 1, no. 2, Jun. 2006. [2] C. Blundo, A. De Santis, and D.R. Stinson. On the contrast in visual cryptography schemes. J. Cryptogr., 12:261-289, 1999. [3] J. B. Feng, H. C. Wu, C. S. Tsai, Y. F. Chang, and Y. P. Chu. Visual secret sharing for multiple secrets. Pattern Recognition, 41:3572-3581, 2008. [4] A. Ross and A. A. Othman, “Visual Cryptography for Biometric privacy”, IEEE Transaction on Information Forensics and Security, vol. 6, no. 1, Mar.2011. [5] M. Naor and B A. Shamir. Visual cryptography. in: A. De San tis (Ed.), Advances in Cryptology: Eurpocrypt'94, Lecture Notes in Computer Science, 950: 1-12, 1995. [6] C.C. Wu and L.H. Chen. A study on visual cryptography, Master Thesis. PhD thesis, Institute of Computer and Information Science, National Chiao Tung University, Taiwan, R.O.C., 1998. [7] M. Naor and A. Shamir “Visual cryptography:Improving the contrast via the cover base” IACR Eprint archive, 1996. [8] C. Blundo and A. De Santis and D.R. Stinson, “On the contrast in visual cryptography schemes”, Jurnal pf cryptography, vol. 12, pp. 261-289, 1996. [9] G. Ateniese and C. Blundo and A. De Santis and D.R. Stinson,“Extended Schemes for Visual Cryptography”, Theoretical Computer Science, 1996. [10] Z. Zhouand and G. R. Arce and G. Di Crescenzo, “Halftone visual cryptography” IEEE Trans. Image Process, vol. 15, no. 8, pp...

Words: 715 - Pages: 3

History of Cryptography

...History of Cryptography AN EASY TO UNDERSTAND HISTORY OF CRYPTOGRAPHY Contents 1. Introduction 2. Classical Encryptions (Ancient Times) 3. Classical Encryptions (Middle Ages) The Cipher of Mary Queen of Scots Vigenère Ciphers Uesugi Cipher 3 4 6 6 6 7 4. Modern Ciphers: Ciphers during World War I and the Emergence of Encryption Machines German Communication Cables Disconnected by the United Kingdom Zimmermann Telegram ADFGVX Cipher The Birth of Enigma 8 8 8 8 9 5. Modern Ciphers: Encryptions in the Computer and Internet Era DES Cipher Public-Key Cryptosystem RSA Cipher Decrypting the DES Cipher Responsive Action of Cipher Enhancements for SSL 10 10 10 11 12 12 6. The Future of Encryption 7. Conclusion: Enhancing the Effectiveness of Encryptions used for SSL References 13 14 14 2 © 2013 Thawte, Inc. All rights reserved. Thawte, the thawte logo, and other trademarks, service marks, and designs are registered or unregistered trademarks of Thawte, Inc. and its subsidiaries and affi liates in the United States and in foreign countries. All other trademarks are property of their respective owners. 1. Introduction E ncryption and related technologies are widely and frequently used as a means of ensuring that information is secure, and their importance has been growing with the increasingly widespread utilization of the Internet. The use of encryption can be traced to as far back as about 3000 B.C., during the Babylonian Era. Encryption...

Words: 6411 - Pages: 26

Cryptography

...1. INTRODUCTION Does increased security provide comfort to paranoid people? Or does security provide some very basic protections that we are naive to believe that we don't need? During this time when the Internet provides essential communication between tens of millions of people and is being increasingly used as a tool for commerce, security becomes a tremendously important issue to deal with. There are many aspects to security and many applications, ranging from secure commerce and payments to private communications and protecting passwords. One essential aspect for secure communications is that of cryptography, which is the focus of this chapter. But it is important to note that while cryptography is necessary for secure communications, it is not by itself sufficient. The reader is advised, then, that the topics covered in this chapter only describe the first of many steps necessary for better security in any number of situations. This paper has two major purposes. The first is to define some of the terms and concepts behind basic cryptographic methods, and to offer a way to compare the myriad cryptographic schemes in use today. The second is to provide some real examples of cryptography in use today. I would like to say at the outset that this paper is very focused on terms, concepts, and schemes in current use and is not a treatise of the whole field. No mention is made here about pre-computerized crypto schemes, the difference between a substitution and...

Words: 7926 - Pages: 32

Cryptography Homework 1

...Homework 1 Due September 25, 2014. The answers can be handed in person or submitted electronically on Blackboard. All problems carry 4 points. 1. The probabilities (or frequencies) of the 26 letters of the English alphabet in English text are as follows. Letter A B C D E F G H I Prob. .082 .015 .028 .043 .127 .022 .020 .061 .070 Letter J K L M N O P Q R Prob. .002 .008 .040 .024 .067 .075 .019 .001 .060 Letter S T U V W X Y Z Prob. .063 .091 .028 .010 .023 .001 .020 .001 Using this information, decrypt the following ciphertext which was encrypted using a Shift Cipher: RUNJAWNMQXFCXLJULDUJCNCQNJVXDWCXOYJYNAWNNMNMO XAJAXXVFQNWRFJBJCBLQXXUHXDVDUCRYUHCQNBZDJANOXXC JPNXOCQNFJUUBKHCQNLDKRLLXWCNWCBXOCQNOUXXAJWMLN RURWPLXVKRWNMJWMMXDKUNRCHXDCQNWJUUXFQJUOCQNCX CJUOXAXYNWRWPBBDLQJBFRWMXFBJWMMXXABCQNWHXDJU UXFCQNXCQNAQJUOOXAVJCLQRWPCQNYJCCNAWCQNWHXDMXDKU NCQNFQXUNCQRWPJPJRWCXPRENJVJAPRWXONAAXAJWMCQNWH XDXAMNACQNYJYNA 2. In a one-time pad, if a message m of length is is encrypted with a key k = 0 (i.e., k consists of all 0s) then enck (m) = m. That is why, it is sometimes suggested to prohibit this key. In other words, the keyspace is restricted to strings which are all not zeros. Is the resulting cryptosystem perfectly secure? 3. For every string s, let s be the string formed by taking the bitwise complement of the string s. For example 101 = 010 and 0010 = 1101. Suppose that G is a psuedorandom number generator (PRG) with expansion factor . Which amongst the following functions are...

Words: 448 - Pages: 2

Cryptography - Itec 5001

...Administrative Information Sections applies to: | ITEC and CRJU, ALL (both U and G sections) | Covers Concepts From | Chapter 9 (and other material) | Date Assigned | Monday, November 10, 2014 | Date / Time Due | Monday, December 1, 2014, 11:59pm. Due to the proximity to the end of the semester, only a ONE day late period will be allowed, until Tuesday, December 2, @ 11:59pm | Method of Submission | You may download this document, enter your answers directly into it, and upload it back into Desire-2-Learn (D2L). The assignment must be submitted via D2L – no other method will be accepted | Percentage of overall grade | This lab, including all required deliverables, is worth 6% of the course’s overall grade, or 60 points out of 1000. | DELIVERABLES | For the Virtual Lab component: Make sure that you transfer all files/images indicated in the lab to our local computer. For the part of the assignment in which you answer questions, they should be answered in THIS document.For the Manual / CrypTool 1 component: all answers are to be entered in THIS document. | Value of each question | See each question or component | BONUS | See below | In this assignment, you will: * Encrypt (not decrypt) a message “by hand,” using techniques used from the Whitman/Mattord Principles of Information Security online pdf file and online lecture. * After doing that, you will download the Cryptool 1 software used to perform cryptography. You will then perform the...

Words: 1748 - Pages: 7

Modern Cryptography Research Paper

...CS 6903 - Applied Cryptography Lecture 10: Lecture 10, slides 3-15 Speaker: Giovanni Di Crescenzo, Scribe: Chaitanya Bhorade December 13, 2014 Summary: This document contains notes for Lecture 10, slides 3-15. These are the lecture notes with some additional information by the scribe, for Lecture 10 Slides 3- 15. The primary focus is on Digital Signatures and its constructions. Properties of a digital signature is then discussed. This is followed by some Digital Signature schemes. And finally Digital Signatures in practice are shown to conclude the notes. 1 Introduction Digital Signatures is a concept derived form a normal signature which is used to confirm the origin of a received document. Asymmetric cryptographic technique is been implemented to ensure whether the received document is authenticated or not. With some factors, a digital signature offers more security than a real-life signature. Because it is difficult to convert a digital signature for message m which can be used as a sign a new message m’ A digital signature for a document would be bits which are derived from: the document and the secret key of the signer.The public key is available freely to anyone who wants to verify the signature. Whereas the other key, which is a secret key, is only known to the one that is authorized to generate the signatures which are associated with that public key. 2 Properties of Digital Signature • Integrity: Recipients can be confident that the message has not...

Words: 1535 - Pages: 7

Cryptography

...Symmetric Cryptography Secret writings have been found in many civilizations dating back to thousands of years where wide spread writings were adopted. Some of these civilizations included the Egyptians with their use of hieroglyphics, the Greeks and Spartan and the use of Scytale, and the Romans with the use of the Caesar Cipher. All these encryption methods could be thought of as symmetric encryption, which uses the same key to encrypt and decrypt the ciphertext. With a more contemporary look at symmetric key encryption with computer data, we can classify it into two categories called block ciphers and stream ciphers. The data in a block cipher would be broken down into specific sizes, for example 64-bit blocks or 128-bit blocks, which then the blocks would be encrypted separately. In stream ciphers, data would be encrypted in a stream of bits as oppose to dividing the data into blocks of bits. The decryption process for these two classification of symmetric encryption, of course, would be to use the same encryption key. Differences and Similarities with Symmetric and Asymmetric The fundamental difference between symmetric and asymmetric cryptography would be that asymmetric uses two keys, a public and private key, for encryption and decryption. If a private key is used to encrypt, then a related public key would be used to decrypt. This could also work the other way around when a public key is used to encrypt, then a related private key would be used to decrypt...

Words: 558 - Pages: 3

Cryptography Outline

...Course Title: Cryptography Section 1-1 Topic: Introduction To Cryptography Confidentiality, Integrity, Availability and Authentication How companies use cryptography How penetration testers can also use cryptography Tools, Techniques and Attacks Academics discusses history of encryption. Academics simply encrypt or hash, why aren't people using hashing more? Professional is just, encrypt or not, hash or just verify Section 1-2 Topic: Key Concepts of Cryptography: PKIS & Encryption Learning Objectives: Cryptography is one of the most underrated courses of study in the industry. Of those who do study it, issues with comprehension tend to hinder individual mastery. By taking this course, learners will finally be able to grasp all the critical concepts, theories and practices associated with Cryptography. This Cryptography presentation discusses and demonstrates the key concepts of Cryptography from attacks, PKIs and Encryption in detail. You’ll learn about the difference between public and private keys and about the similarities and differences between symmetry & asymmetry. We’ll also discuss the concept of integrity and confidentiality and their relationships to/with protocols. This Cryptography course will help you master the basics of Cryptography as you begin to develop the discipline needed to become an accomplished pen tester. Keys and Principles 1. Keys 1a. Symmetric - also referred to as same keys, private key, symmetric key - same...

Words: 3749 - Pages: 15

Cryptography

...In the 20th- century cryptography was adopted by international government to protect private and sensitive information and for communication purposes. Cryptography is known as the science of secret writing that enables storage and transfer of information that is hidden from everyone, but only can read by those who are authorized. The concept of cryptography is to protect confidential information and to assure the identity of people who send electronic messages and conduct electronic transactions are who they say they are. There are also various types of cryptography for example symmetric keys or shared- secret cryptography, is when you use the same key to both encrypt and decrypt a message. The most common form of symmetric key cryptography is the data Encryption standard. The second type of cryptography is asymmetric key cryptography, two keys are needed. A message encrypted using one key can only be decrypted using the other and vice versa. One key is called public key and the other is called the private key. Cryptosystem disguises messages, allowing only selected people to see though the disguise. The mechanisms that make up a strong cryptosystem is the size and means used to protect cryptographic keys. The longer the key the harder it is to break the encryption. A cryptosystem is considered strong only until it’s cracked. Strong cryptosystems produce cipher text that always appears random to standard statistical test. They also resist all known attacks on cryptosystem...

Words: 349 - Pages: 2

Cryptography

...History of Cryptography Developments in cryptography | Period | Development | 2000 BC | In Egypt, hieroglyphics were used in inscriptions. | 500-600 BC | Hebrews used the atbash method for encryption. In this method, each letter of the alphabet mapped to a different letter to hide the true meaning of a word. | 487 BC | The Spartans used the scytale for encryption – messages were written on paper wrapped around a wooden rod. The paper was then unwrapped and sent. The recipient could read the message only by wrapping this paper on a rod of the same length and diameter. | 100-44 BC | Julius Caesar used an encryption method similar to the atbash method. He shifted each letter of the alphabet by a fixed number of places to send encrypted messages. | 1379 | Gabrieli di Lavinde developed the nomenclator. | 1466-1467 | The first polyalphabetic cipher was invented, which was much stronger than the nomenclator. | 1518 | Johannes Trithemius invented a steganographic cipher in which each letter was represented as a word taken from a succession of columns. | 1553 | Giovan Batista Belaso introduced the use of a passphrase as the key for a repeated polyalphabetic cipher. In 1563, Giovanni Battista Porta introduced the digraphic cipher and classified ciphers as transposition, substitution, and symbol substitution. | 1585 | Blaise de Vigenere developed the polyalphabetic substitution cipher. William Frederick Friedman published a book on cryptography, and is known as...

Words: 1015 - Pages: 5

Cryptography

...Define one type of cryptography and describe the security features. Asymmetric Cryptography: Digital Signatures Most of the time when we mention cryptography, or put asymmetric in front of it we are met with just plain blank stares. In the following paragraphs I will attempt to explain what it is, and give examples on its use. First an explanation of Public Key Infrastructure, or PKI. A cryptographic system uses two keys, a public key known to everyone and a private key, the private key has full control to the key owner, and has to keep in secured environment. A unique feature to the public key system is that the public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them. Moreover, it is virtually impossible to distinguish the private key if you know the public key. When employee A wants to send a secure message to employee B, you use the employee B’s public key to encrypt the message. Employee B, then uses their private key to decrypt it. Public Key cryptography, is also called asymmetric encryption because it uses two keys instead of one key (symmetric encryption). Next, for my example of a process that utilizes asymmetric cryptography, is Digital Signatures. I will be using employee’s A and B as my subjects to explain the digital signature process. First, from employee A’s point of view the signing process is simple. This is because few steps are...

Words: 589 - Pages: 3