Cryptograph y and network security seventh edition by william stallings chapter 3 classical. The internet is a worldwide network of connected computers. Cipher algorithm for transforming plaintext to ciphertext. Privatekey encryption algorithms a privatekey or secretkey, or singlekey encryption algorithm is one where the sender and the recipient share a common, or closely related, key all traditional encryption algorithms are privatekey overview of a privatekey encryption system and attacker 912010 classical cryptography. With the use of symmetric encryption, the principal security problem is maintaining the secrecy of the key. Classical encryption techniques as opposed to modern cryptography symmetrickey. Almost all secret key ciphers are essentially a combination of two simple techniques. Chapter 2 classical encryption techniques symmetric encryption, also referred to as conventional encryption or singlekey encryption, was the only type of encryption in use prior to the development of publickey encryption in the 1970s. Chapter 2 classical encryption techniques flashcards. Symmetric key encryption algorithm uses same cryptographic keys for both. Basic vocabulary of encryption and decryption plaintext. Classical cryptography and quantum cryptography geeksforgeeks. Classical encryption techniques symmetric cipher model. Cryptanalysis the process of attempting to discover x or k or both is known as cryptanalysis.
Analysis of classical encryption techniques in cloud. Classical encryption techniques free download as powerpoint presentation. Chosen plaintext attacker selects plaintext and gets ciphertext chosen international it university is 09 spring 2017 lecture 2. Classical encryption techniques cryptography cipher. In case m 3, the encryption can be expressed in terms of the matrix multiplication as follows. The us national bureau of standards nbs declared it in 1976 the standard for us government cryptography, for documents that are sensitive but not classi. Apr 18, 2020 classical encryption techniques, there are two basic building blocks of all encryption techniques. Chapter 2 classical encryption techniques flashcards quizlet. Request pdf analysis of classical encryption techniques in cloud computing cloud computing has become a significant computing model in the it industry. Classical encryption techniques raj jain washington university in saint louis saint louis, mo 63. Mar 01, 20 plaintext encrypted two letters at a time.
Two building blocks of all classical encryption techniques are substitution and transposition. Encryption is a security method in which information is encoded in such a way that only authorized user can read it. Classical encryption techniques in network security 1. This approach is also called as posteriori approach. Pis a finite set of possible plaintexts cis a finite set of possible ciphertexts k, the keyspace, is a finite set of possible keys e. Given the algorithm and ciphertext, an attacker cannot obtain the key or plaintext. This is the limitation of this encryption technique that this private key must be distributed only among the authorized sender and receiver. K d c ek e, p p dk d, ek e, p keyless cipher a cipher that does not require the use of a key key cannot be changed if the encryption algorithm should fall into the interceptor s hands, future messages can still be kept secret because the. Such a scheme is known as a cryptographic system cryptosystem or a cipher. Symmetric encryption, also referred to as conventional encryption or singlekey encryption, was the only type of encryption in use prior to the development of publickey encryption1. Building blocks of classical encryption techniques. Classical encryption techniques in network security. The many schemes available today for encryption and decryption. This is my implementation for some classical encryption techniques.
Classical encryption techniques linkedin slideshare. Lawrie browns slides supplied with william stallings s book cryptography and network security. Network security classical encryption techniques 2. The process of protecting information by transforming encrypting it into an unreadable format is called cryptography. Techniques used for deciphering a message without any knowledge of the enciphering details fall into the area of cryptanalysis. In a modern block cipher but still using a classical encryption method, we replace a block of n bits from the plaintext with a blockofnbitsfromtheciphertext. Substitution means replacing an element of the plaintext with an element of cipher text. Classical and modern encryption techniques are investigated and then compared here. This tutorial covers the basics of the science of cryptography. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Introduction to finite fields and their applications pdf. Only those who possess secret key can decipher decrypt the message into plain text. This is the original intelligible message or data that is fed into the algorithm as input.
Classical encryption techniques computer science and. Classical encryption techniques in cryptography and network security. Analytical study on encryption techniques and challenges. If a pair is a repeated letter, insert a filler like x, ex. Substitutionreplace one element in plaintext with another transpositionrearrange elements product systemsmultiple stages of substitutions and transpositions number of keys used. Ahmed elshafee, acu spring 2014, information security.
It uses encryption algorithm to generate ciphertext that can only be read if decrypted. Thisgeneralideaisillustrated in figure 1 for the case of n 4. Classical encryption techniques lecture notes on computer and network security. Cryptanalysis of monoalphabetic the relative frequencies of the letters in the. Classical encryption techniques in cryptography and. On average, need to try half of all possible keys time needed proportional to size of key space. Disadvantages practical consideration may force us to test algorithm for small number of instances. Loai tawalbeh computer engineering department jordan university of science and technology jordan cpe 542. Nov 07, 2016 lecture slides by lawrie brown for cryptography and network security, 5e, by william stallings, chapter 2 classical encryption techniques. The national security agency nsa is responsible for higher levels of security. Integrating classical encryption with modern technique. The encryption takes m successive plaintext letter and substitutes them for m ciphertext letters.
The many schemes used for encryption constitute the area of study known as cryptography. There are two types of encryptions schemes as listed below. Cryptography and network security for computers and email. Classical encryption techniques in cryptography and network. Classical techniques are based on two building blocks. Pis a finite set of possible plaintexts cis a finite set of possible ciphertexts k, the keyspace, is a finite set of possible keys e is a finite set of encryption functions. Communication encrypts as com x munication if the letters appear on the same row of your table, replace them with the letters to their immediate right respectively wrapping around to the left side of the row if a letter in the original pair was on the right side of the row. Classical encryption techniques jordan university of.
Comparing classical encryption with modern techniques. A substitution technique is one in which the words or text of plaintext are replaced by other letters or by numbers or symbols. View homework help 02classical from math 201 at punjab college multan. Loai tawalbeh fall 2005 basic terminology plaintext the original message ciphertext the coded message. If we look at the figure below we can better understand. Fully homomorphic encryption without modulus switching. A general paradigm for algorithm design threestep process. Discovering the algorithm that performs better for large as well as for small instances is critical. It is the hash function that generates the hash code, which helps. These chips are widely available and incorporated into a number of products. This allows the sharing of electronic information and resources. Classical encryption techniques there are two requirements for secure use of conventional encryption. Starting with the origins of cryptography, it moves on to explain cryptosystems, various traditional and modern ciphers.
The secret key is also input to the encryption algorithm. A stream cipher processes the input elements continuously, producing output element one at a time, as it goes along. Of the plaintext is viewed as a sequence of bits, then substitution involves replacing plaintext bit patterns with ciphertext bit patterns 2. Classical techniques symmetric model substitution transposition rotor machines steganography characterising cryptographic systems operations used for encryption. This is essentially the encryption algorithm run in reverse. Classical encryption techniques in cryptography and network security free download as powerpoint presentation. A symmetric encryption scheme has five ingredients as shown in the following figure. The strategy used by the cryptanalysis depends on the nature of the encryption scheme and the. Classical cryptography has two types of techniques. Substitution the letters of plaintext are replaced by other letters or by numbers or symbols. Sep 16, 20 classical encryption techniques in network security 1.
Some basic vocabulary of computer and network security and a. Classical encryption techniques developed lowcost chip implementations of data encryption algorithms. Replace characters of plaintext by other characters. Symmetric encryption, also referred to as conventional encryption or singlekey encryption, was the only type of encryption in use prior to the development of publickey encryption in the 1970s. In terms of security, hashing is a technique used to encrypt data and generate unpredictable hash values. Pdf comparing classical encryption with modern techniques. Fully homomorphic encryption without modulus switching from classical gapsvp. Classical encryption techniques washington university.
It explains how programmers and network professionals can use cryptography to maintain the privacy of computer data. Bruteforce attack try every key to decipher the ciphertext. With the message x and the encryption key k as input, the encryption algorithm forms the ciphertext y y1, y2. Sender and receiver must have obtained copies of the secret key in a secure fashion and must keep the key secure. In classical cryptography, the various parameters used by a decryption algorithm are derived from the same secret key that was used in the encryption algorithm. It takes the ciphertext and the secret key and produces the original plaintext. To introduce the rudiments of the vocabulary of computer and network security and that of encryptiondecryption. A symmetric encryption scheme has five ingredients. In general, though, n is set to 64 or multiples thereof.
Another way of classifying cryptographic algorithm are mono alphabetic cipher and poly alphabetic cipher 22 based on the mapping of plain text alphabet to cipher text alphabet. We can write this as y ekx this notation indicates that y is produced by using encryption algorithm e as a function of the plaintext x, with the specific function determined by the value of the key k. It remains by far the most widely used of the two types of encryption. Public key encryption algorithm uses pair of keys, one of which is a secret key and one of which is public. Start studying chapter 2 classical encryption techniques. If the plaintext is viewed as a sequence of bits, then substitution method comes into picture which involves replacing plaintext bit patterns with cipher text bit patterns. In the symmetric cryptography a single key is used for encrypting and decryption the data. The encryption algorithm performs various substitutions and transformations on the plaintext. Playfair cipher one approach to improve security was to encrypt multiple letters the playfair cipher is an example invented by charles wheatstone in 1854, but named after his friend baron playfair. These two keys are mathematically linked with each other. Secret key ciphers use a secret key for encryption.