1) The document discusses cryptography and describes it as the art and science of converting ordinary information into gibberish and back again. 2) It explains some basic terms used in cryptography like plaintext, ciphertext, encryption, decryption, and keys. 3) Applications of cryptography mentioned include securing email, banking, intellectual property, and providing privacy for stored information.

1. Created By : Rahul Khanvani
Roll No : 47
Department Of Computer Science
Cryptography:
Securing the Information.
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2. Introduction
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3. 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 
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4. » 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 ?
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5. » 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 ?
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6. » 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
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7. » Defending against external/internal hackers
» Securing E-commerce
» Securing bank accounts/electronic transfers
» Securing intellectual property
Information Security for…
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8. » 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
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9. How To Send A Secure Email Or Password Protected Email?
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10. Types Of Cryptography
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11. Secret Writing
Steganography
Cryptography
Types of Secret Writing
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12. » Steganography – covered writing
 – is an art of hiding information
» Popular contemporary steganography
technologies hide information in images.
Steganography
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14. » 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:-
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15. » 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
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16. » Public (asymmetric) key cryptography – a public key used for encryption
and private key for decryption
» Key distribution problem solved
Public Key Cryptography
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17.  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)
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18.  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)
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19. » 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?
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20. Thank You…
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