Crytography

PRESENTED BY:

JATIN KAKKAR - 26 JESO P . JAMES - 28

• INTODUCTION• HISTORY• OBEJECTIVE & OVERVIEW• APPLICATIONS• CRYPTOGRAPHY COMPONENTS• TERMINOLOGY• ASPECTS• TYPES OF CRYPTOGRAPHY• ADVANTAGES• CONCLUSION• REFERENCES

• Cryptography is the science of information security.

• The word is derived from the Greek kryptos, meaning hidden.

• Cryptography includes techniques such as microdots, merging words with images, and other ways to hide information in storage or transit.

• Confidentiality:- the information cannot be understood by anyone for whom it was unintended.

• Integrity :-the information cannot be altered in storage or transit between sender and intended receiver without the alteration being detected.

• Authentication :-the sender and receiver can confirm each others identity and the origin/destination of the information.

Overview of Cryptography & Its Applications

• People wants and needs privacy and security while communicating.

• In the past, cryptography is heavily used for militaryapplications to keep sensitive information secret from enemies (adversaries).

• Nowadays, with the technologic progress as our dependency on electronic systems has increased we needmore sophisticated techniques.

• Cryptography provides most of the methods and techniquesfor a secure communication

6

Cryptography components

• Encryption – It is a process of changing or converting normal text or data information into gibberish text.

• Decryption – It is a process of changing or converting gibberish text back to correct message or data by using encryption method.

Cryptology : All-inclusive term used for the study of securecommunication over non-secure channels.

Cryptography : The process of designing systems to realizesecure communications over non-secure channels.

Cryptoanalysis : The discipline of breaking the cryptographicsystems.

Coding Theory : Deals with representing the informationusing codes. It covers compression, secrecy, anderror correction.

Terminology

The Aspects of Cryptography

• Modern cryptography heavily depends on mathematics and the usage of digital systems.

• It is a inter-disciplinary study of basically three fields:MathematicsComputer ScienceElectrical Engineering

• Without having a complete understanding of crypto analysis(or cryptoanalytic techniques) it is impossible to design good (secure, unbreakable) cryptographic systems.

• It makes use of other disciplines such as error-correcting codescompression.

10

Categories of cryptography

11

• A single common encryption key is used to encode and decode messages.

• Both sender and receiver must know the common key.

• The common key need to be exchanged before hand by some other secure method.

• Symmetric encryption is simple and fast.• But - key management is impractical with

large number of senders and receivers.

11

Symmetric-key cryptography

12

• Asymmetric system under, which two different keys are used to encrypt and decrypt the message or received data packet.

• On public key is used to encrypt the data or message and the private key on receiving end is used to decrypt the message or data packet.

• Each user has a Public key and a corresponding Private (secret) key

Asymmetric-key cryptography

Asymmetric-key cryptography

Keys used in cryptography

• Sender”sign” messages by means of his private secret key.

• Recipient verify the senders signature by means of the senders public key.

• The senders identity is certified by means of a”Certificate” which is digitally signed by a trusted third party.

• public-key cryptography Increased security and convenience.

• public-key cryptography is best suited for an open multi-user environment.

• Symmetric encryption is simple and fast.

• cryptography = physics + Information theory

• Information is physical.

• Information gain implies disturbances.