Cryptography and Digital Signature
#1

Presented by:
Sreekanth.A

[attachment=10854]
Abstract: Cryptography's aim is to construct schemes or protocols that can still accomplish certain tasks even in the presence of an adversary. A basic task in cryptography is to enable users to communicate securely over an insecure channel in a way that guarantees their transmissions' privacy and authenticity. Providing privacy and authenticity remains a central goal for cryptographic protocols, but the field has expanded to encompass many others, including e-voting, digital coins, and secure auctions. This paper explains what cryptography is about and how we can scientifically justify a cryptographic scheme's security.
Key Words: Cipher text, Public key, Private key, Crptography
1.0 Introduction
The origin of the word cryptology lies in ancient Greek. The word cryptology is made up of two components: "kryptos", which means hidden and "logos" which means word. Cryptology is as old as writing itself, and has been used for thousands of years to safeguard military and diplomatic communications. For example, the famous Roman emperor Julius Caesar used a cipher to protect the messages to his troops. Within the field of cryptology one can see two separate divisions: cryptography and cryptanalysis. The cryptographer seeks methods to ensure the safety and security of conversations while the cryptanalyst tries to undo the former's work by breaking his systems. The main goals of modern cryptography can be seen as: user authentication, data authentication (data integrity and data origin authentication), non-repudiation of origin, and data confidentiality. In the following section we will elaborate more on these services. Subsequently we will explain how these services can be realized using cryptographic primitives. Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks (like the Internet) so that it cannot be read by anyone except the intended recipient. While cryptography is the science of securing data, cryptanalysis is the science of analyzing and breaking secure communication. Classical cryptanalysis involves an interesting combination of analytical reasoning, application of mathematical tools, pattern finding, patience, determination, and luck. Cryptanalysts are also called attackers. Cryptology embraces both cryptography and cryptanalysis.
2.0 Encryption and decryption
Data that can be read and understood without any special measures is called plaintext or clear text. The method of disguising plaintext in such a way as to hide its substance is called encryption. Encrypting plaintext results in unreadable gibberish called cipher text. You use encryption to ensure that information is hidden from anyone for whom it is not intended, even those who can see the encrypted data. The process of reverting cipher text to its original plaintext is called decryption.
3.0 Strength of cryptography
Cryptography can be strong or weak, as explained above. Cryptographic strength is measured in the time and resources it would require to recover the plaintext. The result of strong cryptography is cipher text that is very difficult to decipher without possession of the appropriate decoding tool. How difficult? Given all of today’s computing power and available time—even a billion computers doing a billion checks a second—it is not possible to decipher the result of strong cryptography before the end of the universe. One would think, then, that strong cryptography would hold up rather well against even an extremely determined cryptanalyst. Who’s really to say? No one has proven that the strongest encryption obtainable today will hold up under tomorrow’s computing power. However, the strong cryptography employed by PGP is the best available today. Vigilance and conservatism will protect you better, however, than claims of impenetrability. PGP is a cryptosystem.
4.0 How does cryptography work?
A cryptographic algorithm, or cipher, is a mathematical function used in the encryption and decryption process. A cryptographic algorithm works in combination with a key—a word, number, or phrase—to encrypt the plaintext. The same plaintext encrypts to different cipher text with different keys. The security of encrypted data is entirely dependent on two things: the strength of the cryptographic algorithm and the secrecy of the key. A cryptographic algorithm, plus all possible keys and all the protocols that make it work comprise a cryptosystem.
5.0 Types of Cryptography
5.1 Conventional cryptography

In conventional cryptography, also called secret-key or symmetric-key encryption, one key is used both for encryption and decryption. The Data Encryption Standard (DES) is an example of a conventional cryptosystem that is widely employed by the Federal Government.
5.2 Caesar’s Cipher
An extremely simple example of conventional cryptography is a substitution cipher. A substitution cipher substitutes one piece of information for another. This is most frequently done by offsetting letters of the alphabet. Two examples are Captain Midnight’s Secret Decoder Ring, which you may have owned when you were a kid, and Julius Caesar’s cipher. In both cases, the algorithm is to offset the alphabet and the key is the number of characters to offset it. For example, if we encode the word “SECRET” using Caesar’s key value of 3, we offset the alphabet so that the 3rd letter down (D) begins the alphabet.
So starting with
ABCDEFGHIJKLMNOPQRSTUVWXYZ
and sliding everything up by 3, you get
DEFGHIJKLMNOPQRSTUVWXYZABC
where D=A, E=B, F=C, and so on.
Using this scheme, the plaintext, “SECRET” encrypts as “VHFUHW.” To allow someone else to read the cipher text, you tell them that the key is 3.Obviously, this is exceedingly weak cryptography by today’s standards, but it worked for Caesar, and it also illustrates how conventional cryptography works.
5.3 Key management and conventional encryption
Conventional encryption has benefits. It is very fast. It is especially useful for encrypting data that is not going anywhere. However, conventional encryption alone as a means for transmitting secure data can be quite expensive simply due to the difficulty of secure key distribution. Recall a character from your favorite spy movie: the person with a locked briefcase handcuffed to his or her wrist. What is in the briefcase, anyway? It’s probably not the missile launch code/biotoxin formula/invasion plan itself. It’s the key that will decrypt the secret data. For a sender and recipient to communicate securely using conventional encryption, they must agree upon a key and keep it secret between themselves. If they are in different physical locations, they must trust a courier, the Bat Phone, or some other secure communication medium to prevent the disclosure of the secret key during transmission. Anyone who overhears or intercepts the key in transit can later read, modify, and forge all information encrypted or authenticated with that key. From DES to Captain Midnight’s Secret Decoder Ring, the persistent problem with conventional encryption is key distribution: how do you get the key to the recipient without someone intercepting it?
Reply
#2


to get information about the topic digital signature full report ,ppt and related topic refer the page link bellow

http://studentbank.in/report-digital-sig...t-download

http://studentbank.in/report-digital-sig...ull-report

http://studentbank.in/report-digital-sig...ars-report

http://studentbank.in/report-a-new-forwa...ure-scheme

http://studentbank.in/report-digital-sig...oad?page=2

http://studentbank.in/report-cryptograph...-signature

http://studentbank.in/report-public-key-...-signature
Reply

Important Note..!

If you are not satisfied with above reply ,..Please

ASK HERE

So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this page
Popular Searches: digital signature examp, who is julius nyerere, digital signature seminar, digital signature army, digital signature in matlab, digital signature document, digital signature cosign,

[-]
Quick Reply
Message
Type your reply to this message here.

Image Verification
Please enter the text contained within the image into the text box below it. This process is used to prevent automated spam bots.
Image Verification
(case insensitive)

Possibly Related Threads...
Thread Author Replies Views Last Post
  Project Evaluation and Review Technique (PERT) and Critical Path Method (CPM) seminar class 0 3,318 14-04-2011, 10:12 AM
Last Post: seminar class
Thumbs Up Economics and Electronic Commerce:Survey and Directions for Research projectsofme 0 1,513 08-10-2010, 12:23 PM
Last Post: projectsofme
  Economics and Environmental Law dealing with competition law and environmental project report tiger 0 2,043 06-02-2010, 02:44 PM
Last Post: project report tiger

Forum Jump: