Some Basic Terms Plain Text/Clear Text :Data that can be read and understood without any special measure. Cipher Text :The unreadable plain text after encryption. Encryption :The method of disguising to hide its substance. Decryption :The method of reverting cipher text to its original plain text.
CRYPTANALYSIS vs. CRYPTOGRAPHY? Cryptography is a science of using mathematics to encrypt and decrypt data. It enable us to store and transmit sensitive data over unsecure network. Cryptanalysis is the science of analyzing and breaking secure communication.
In conventional cryptography(symmetric key encryption)one key is used both for encryption and decryption. i.e. Caesar’s cipher This cryptography is very fast but is quite expensive due to difficulty of secure key distribution.
It uses two key, one key for encryption(public key) and one for decryption(private key). We publish the data with the public key to the world while keeping the private key. The need for sender and receiver to share secret key via some secure channel is eliminated.
Combines strengths of both methodsAsymmetric distributes symmetric key. Also known as a session key(one time only secret key). Symmetric provides bulk encryptioni.e. PGP
KEYS Work with cryptographic algorithm to produce a specific cipher text. Larger keys are secure for longer period of time.
STEGANOGRAPHY Greek for “covered writing” “The art and science of writing hidden messages in such a way that no one apart from the intended recipient even knows that a message has been sent.” It makes use of seemingly innocent cover files such as text, audio, and image files
IMAGE BASED TECHNIQUE Least Significant Bit Insertion Replaces the LSB with the message to be encoded. Simple, but susceptible to lossy compression and image manipulation Masking and Filtering Masks secret data over the original data by changing the luminance of particular areas During masking, it embed the message within significant bits of the cover image
Digital Watermarking – provides identification pertaining to the owner; i.e. license or copyright information - Invisible vs. Visible Fingerprinting – provides identification of the user; used to identify and track illegal use of content
A web hosting is a type of Internet hosting that allows individuals and organizations to make their website accessible via the World Wide Web or locally in the network. The most basic is web page and small-scale file hosting, where files can be uploaded via File Transfer Protocol (FTP) on the server.
DNS A Domain Name Service translates queries for domain names (which are easier to understand and utilize when accessing the internet) into IP addresses for the purpose of locating computer services and devices worldwide. For example, the domain name www.ethicalpirates.com translates to the addresses 172.16.32.254 (IPv4).
APACHE (Web Server) Web servers are computers that deliver (serves up) Web pages. Every Web server has an IP address and possibly a domain name. Any computer can be turned into a Web server by installing server software and connecting the machine to the internet
A firewall is a rule or set of rules create to permit or deny network transmissions based on a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. i.e. Packet Filter, Proxy Server etc.
REFERENCES www.jjtc.com/stegdoc/steg1995.html “Information Hiding: Techniques for Steganography and Digital Watermarking” – S. Katzenbeisser, F. Petit colas “RSA Security’s Official Guide to Cryptography” by S. Burnett and S. Paine, Osborne/McGraw-Hill, 2001 The Code Breaker-David Khan
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.