NAME - LAKHI CHAND SINGH THE CALCUTTA ANGLO GUJARATI COLLEGE BCA 6TH SEMESTER 2014-2017

1. CRYPTOGRAPHY

2. INTRODUCTION
CATEGORIES OF CRYPTOGRAPHY
CRYPTOGRAPHIC FUNCTIONS
BASIC TERMS
ENCRYPTION & DECRYPTION
SECURITY THREATS
SECURITY GOALS
APPLICATIONS
CONCLUSION
CONTENTS

3. Cryptography is the science and art of transforming messages
to make them secure and immune to attack.
It comes from Greek word "secret writing"
WHAT IS CRYPTOGRAPHY

5. CATEGORIES OF CRYPTOGRAPHY
ASYMMETRIC KEY
CRYPTOGRAPHY
SYMMETRIC KEY
CRYPTOGRAPHY

6. • Symmetric-key cryptography started thousands of years ago when people
needed to exchange secrets (for example, in a war). We still mainly use
symmetric-key cryptography in our network security. Also known as secret
key
• In symmetric-key cryptography, the same key is used by the sender(for
encryption) and the receiver (for decryption).The key is shared.
SYMMETRIC KEY CRYPTOGRAPHY

7. • Also known as public key cryptography.
• Sender & receiver uses different keys for encryption &
decryption
ASYMMETRIC KEY CRYPTOGRAPHY

8. • PLAIN TEXT
• CIPHER TEXT
• CIPHER
• CRYPTOLOGY
• KEY
BASIC TERMS

9. SECRET KEY FUNCTIONS
• Using a single key for encryption/decryption.
• The plaintext and the cipher text having the same size.
• Also called symmetric key cryptography
PUBLIC KEY FUNCTIONS
• Each individual has two keys
– a private key (d): need not be reveal to anyone
– a public key (e): preferably known to the entire world
• Public key crypto is also called asymmetric crypto.
HASH FUNCTIONS
• A mathematical transformation that takes a message of arbitrary length
and computes it a fixed-length (short) number.
TYPES OF CRYPTOGRAPHIC FUNCTIONS

10. TRADITIONAL
CIPHERS
SUBSTITUTION
CIPHER
TRANSPOSITION
CIPHER

11. • A substitution technique is one in which the letters/number/symbols of plaintext
are replaced by other letters/numbers/symbols.
e.g. A D, T Z
2 5, 3 6
SUBSTITUTION CIPHERS
TRANSPOSITION CIPHER
• In the transposition technique the positions of letters/numbers/symbols in
plaintext is changed with one another.
• Plain text: MEET ME AFTER PARTY
• Cipher text: TEMEEMEFAPTRYRAT
• KEY USED: 421635
1 2 3 4 5 6
M E E T M E
A F T E R P
A R T Y
4 2 1 6 3 5
T E M E E M
E F A P T R
Y R A T

12. ENCRYPTION & DECRYPTION
ENCRYPTION
The process of converting plaintext into cipher text
DECRYPTION
The process of converting cipher text into plaintext
ENCRYPTION & DECRYPTION

13. THREATS

14. CONFIDENTIALITY INTEGRITY
SECURE
NON-REPUDIATION
SECURITY GOALS

15. • Defense services
• Digital Signatures
• Identification and Authentication
• Internet payment systems
• E- Commerce
• Access control
• Data security
APPLICATIONS

16. By using of encryption techniques a fair unit of
confidentiality, authentication, integrity, access
control and availability of data is maintained.
CONCLUSION