Cryptography

Created By : Rahul Khanvani

Roll No : 47

Department Of Computer Science

Cryptography:

Securing the Information.

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Introduction


Introduction

» EPFT UIJT MPPL MJLF OPOTFOTF UP ZPV ?

Does it look like nonsense to you ?

Did you notice that I asked you the same question twice ?

Confused ?

» Replace Each word With its Alphabet used before.

» The Cryptography is Simple


» Cryptography is the art and science of converting ordinary information into gibberish and converting it back to its original, meaningful form.

» Its Amazing how rotating the alphabets by even just one position is enough to confuse human mind !

» We Call It Rotating Words.

» To convert data in meaningful form you need an algorithm ,

» you can also create your own small algorithm.

What Is Cryptography ?


» If You Say No Then I Can Say You May B Don’t Use Cryptography.

Do You Use Gmail ?

Do You use Facebook ?

Have you Ever Opened a File Containing Password ?

Did U Use HTTPS Site ?

Do You Fill Forms on Internet ?

» Most Of You Are Saving Your GF/BF’s No. As Their Nick Names Is Also A Kind Of Cryptogrpahy.

E.g Saving Ur G.F’s No As “Battery Low” To Hide The Contact From Relatives.

Who Uses Cryptography ?


» Plaintext – A message in its natural format readable by an attacker

» Cipher text – Message altered to be unreadable by anyone except the intended recipients

» Key – Sequence that controls the operation and behavior of the cryptographic algorithm

» Key-space – Total number of possible values of keys in a crypto algorithm

» Encryption Plain text Cipher text

» Decryption Cipher text Plain text

Terms Used In Cryptography


» Defending against external/internal hackers

» Securing E-commerce

» Securing bank accounts/electronic transfers

» Securing intellectual property

Information Security for…


» Pervasiveness of email/networks

» Online storage of sensitive information

» Insecure technologies (e.g. wireless)

» Trend towards paperless society

» Weak legal protection of email privacy.

Threats to Information Security


How To Send A Secure Email Or Password Protected Email?


Types Of Cryptography


Secret Writing

Steganography

Cryptography

Types of Secret Writing


» Steganography – covered writing

– is an art of hiding information

» Popular contemporary steganography

technologies hide information in images.

Steganography



» Encryption means the transformation of data by the use of Cryptography to produce unintelligible data to ensure confidentiality

» The inverse function of encryption is called as decryption

Encryption and decryption:-


» Private (symmetric, secret) key – the same key used for encryption/decryption

» Problem of key distribution

» How Do Both Person Agree On Same Key ?

Private Key Cryptography


» Public (asymmetric) key cryptography – a public key used for encryption and private key for decryption

» Key distribution problem solved

Public Key Cryptography


DES (Data Encryption Standard) and derivatives: double DES and triple DES

IDEA (International Data Encryption Standard)

Blowfish

RC5 (Rivets Cipher #5)

AES (Advance Encryption Standard)

Currently Available Crypto Algorithms (private key)


RSA (Rivest, Shamir, Adleman)

DH (Diffie-Hellman Key Agreement Algorithm)

ECDH (Elliptic Curve Diffie-Hellman Key Agreement Algorithm)

RPK (Raike Public Key)

Currently Available Crypto Algorithms (public key)


» Algorithms are not theoretically unbreakable: successful attacks in the future are possible.

» Encryption does not guarantee security!

» Many ways to beat a crypto system NOT dependent on cryptanalysis, such as:

Viruses, worms, hackers, etc.

TEMPEST attacks,

Unauthorized physical access to secret keys

» Cryptography is only one element of comprehensive computer security

How Secure are Today’s Technologies?


Thank You…

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