17-05-2014, 12:46 PM
Information Hiding Cryptography & Steganography
Information Hiding Cryptography .ppt (Size: 1.57 MB / Downloads: 199)
What is Cryptography
Protecting information by transforming it into an unreadable format
Encryption is the process that transforms the data into the unreadable format, Decryption restores it to its original format.
Used to prevent information from “falling into the wrong hands”
Data is only available to the people that are supposed to see it
A little history
Cryptography is not new
1900 BC hieroglyphics
60 BC Caesar cipher
Simple substitution cipher
Replace each letter with alphabet shifted K letters
If K=3 then “hello” becomes “khoor”
Thomas Jefferson considered by some to be the father of U.S. cryptography
Cryptography vital during World Wars
German Enigma machine in WW II
“Lucifer” IBM project in late 1960’s became successful commercial product
How does it work
A few terms
Plaintext – the original message
Ciphertext – the encrypted message
Encryption – how the message is scrambled
Decryption – how the message is unscrambled
Cryptographic system – specific method of encryption and decryption (also called a cipher or cryptosystem)
Transposition – rearranging elements
Substitution – replacing elements
Encryption is NOT the same as a code
Code – words are substituted for other words
Navajo code talkers from WW II
“dah-he-tih-hi (hummingbird) substituted for “fighter plane”
“besh-lo” (iron fish) meant “submarine”
Different Methods
Symmetric – same key is used for both encryption and decryption (also called private key encryption)
DES - Data Encryption Standard
Loosely based on Lucifer which used 112 bit keys
NSA asked that the key length be shortened to 56 bits
Triple-DES – variant of DES
AES - Advanced Encryption Standard
IDEA – International Data Encryption Algorithm
Uses of Cryptography
SSL – Secure Socket Layer
Used to encrypt web-based transactions
Usually 40, 56, or 128-bit key lengths
Very popular with e-tailers
Look for little padlock on your browser
TLS – Transport Layer Security protocol
Developed by Internet Engineering Task Force (IETF) and based on SSL
SET – Secure Electronic Transactions
The SET™ Specification, is an open technical standard for the commerce industry developed by Visa and MasterCard as a way to facilitate secure payment card transactions over the Internet.
Summary
What is the Importance and Significance of this material?
How does this topic fit into the subject of “Voice and Data Security”?