cryptography. topics of seminar introduction & related terms categories and aspects of...
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CRYPTOGRAPHY
TOPICS OF SEMINAR
• Introduction & Related Terms• Categories and Aspects of
cryptography• Model of Network Security• Encryption Techniques• Public key cryptosystem• Application• Bibliography
DEFINATION OF CRYPTOGRAPHY• Cryptography is the study of
mathematical techniques related to the aspects of information security, such as confidentially, data integrity and entity authentication.
• Cryptography is not only means of providing information, but rather one set of techniques.
Related Terms
• Plain text :-Original Message• Cipher text:-Coded Message.• Encryption:-The process of converting
plain text into cipher
text.• Decryption:-Restoring plain text from cipher text.
• Cryptography:-The science or area of Encryption & Decryption • Cryptanalysis:-The science of analysis or breaking of secure communication • Cryptology :- The area of cryptography and cryptanalysis together
Categories OF CRYPTOGRAPHY
There are two types of cryptographic algorithm
• Symmetric key
• Asymmetric key
GOALS OF CRYPTOGRAPHY
• Confidentially• Data Integrity• Authentication• Non-repudiation
ASPECTS OF SECURITY
• Security Service
• Security Mechanism
• Security Attacks Passive Attacks Active Attacks
MODEL OF NETWORK SECURITY
There are four basic tasks in designing a particular security services.
• Design an algorithm• Generate a secret information • Develop methods for distribution
and sharing• Specify the protocol
SUBSTITUTION TECHNIQUES• CAESAR CIPHER• To Encrypt using Caesar's key value of
3,we offset the alphabet so that the 3rd letter down (D) begins the alphabet.
• ABCDEFGHIJKLMNOPQRSTUVWXYZ and sliding everything up by 3, you get DEFGHIJKLMNOPQRSTUVWXYZABC where D=A, E=B, F=C, and so on.
• "SECRET" encrypts as "VHFUHW."
TRANSPOSITION TECHNIQUES• Plain text = “meet me after this
party”• Key = 2• m e m a t r h s a t e t e f e t i p r y• Cipher text
=“mematrshsatetefetipry”
A more complex scheme is • Key 4 3 1 2 5 6 7• plaintext: a t t a c k p o s t p o n e d u n t I l t• Ciphertext:
TTNAPTTSUAODCOLKNLPET
DES ALGORITHM
Public Key Cryptosystem: Secrecy
Encryption Algorithm
Source A
Source Destination
Decryption Algorithm
Key pair source
Cryptanalyst
Destination B
B’s public key
B’s private key
Public Key Cryptosystem: Authentication
Encryption Algorithm
Source A
Source Destination
Decryption Algorithm
Key pair source
Cryptanalyst
Destination B
A’s private key
A’s public key
Public Key Cryptosystem: Secrecy & Authentication
Encry.Algori-them
Encry.Algori-them
Decry.Algori-them
Decry.Algori-them
Source
Dest.
Key Pair Source
Key Pair Source
B’s private key B’s public key
A’s public key
Source A
Destination B
A’s private key
APPLICATION
• Secure Communication
• Identification & Authentication
• Secret Sharing
BIBLIOGRAPHY
• Cryptography & Network Security By William Stallings
• WWW.google.com• Computer Network By Andrew S.
Tanenbaum
THANK YOU
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