its a prsentation on cryptography..

1. Cryptography
Presented By:Sanjeev Kumar
Dept: I.T

2. Cryptography Intro
Why Encrypt?
• Protect stored information
• Protect from Unauthorized disclosure
Encryption - process by which plaintext is converted to cipher text using a key
Decryption - process by which cipher text is converted to plaintext (with the
appropriate key)
plaintext (clear text)- intelligible data

3. Cryptography Terminology
Cryptography - art/science relating to encrypting, decrypting information
Cryptanalysis - art/science relating to converting cipher text to plaintext
without the (secret) key

4. Here we have three types of algorithms that we can talk
about:
MODERN CRYPTOGHRAPHY
 Secret Key Cryptography
 Hash Functions
 Public Key Cryptography

5. MODERN CRYPTOGHRAPHY

6. Here we have three types of algorithms that we can talk
about:
MODERN CRYPTOGHRAPHY
 Secret Key Cryptography
 Hash Functions
 Public Key Cryptography

7. MODERN CRYPTOGHRAPHY

8.  Secret Key(Symmetric) Cryptography uses a single
key for both encryption and decryption.
SECRET KEY
CRYPTOGHRAPHY

9.  A single key is used
SECRET KEY
CRYPTOGHRAPHY
 Sender uses the key to encrypt
 Receiver uses the same key to decrypt
 Key must be known to both the sender and the
receiver
 The difficulty is the distribution of the key

10. Secret key cryptography algorithms that are in use
today :
SECRET KEY
CRYPTOGHRAPHY
 Data Encryption Standard (DES):
 Advanced Encryption Standard (AES):
 International Data Encryption Algorithm (IDEA):

11. SECRET KEY SUMMARY

12.  Hash functions(One-way cryptography) have no key
since plaintext cannot be recovered from the
ciphertext.
HASH FUNCTIONS

13.  Called message compiler and one-way encryption
HASH FUNCTIONS
 No key is used
 Digital fingerprint
 Provide the integrity

14. Hash algorithms that are in common use today:
HASH FUNCTIONS
 Message Digest (MD) algorithms:
 HAVAL (Hash of Variable Length):
 Tiger:

15. PUBLIC KEY CRYPTOGHRAPHY
 Public Key(Asymmetric) Cryptography. Two keys are
used. One for encryption, one for decryption.

16. PUBLIC KEY CRYPTOGHRAPHY
 Developed in the last 300-400 years.
 Martin Hellman and graduate student Whitfield
Diffie
 A two-key crypto system
 Mathematical functions

17. Public key Cryptography
Secret key Cryptography

18. Secret Key Cryptography
With secret key cryptography, a single key is
used for both encryption and decryption. As shown
in Figure 1A, the sender uses the key (or some set
of rules) to encrypt the plaintext and sends the
ciphertext to the receiver. The receiver applies the
same key (or ruleset) to decrypt the message and
recover the plaintext. Because a single key is used
for both functions, secret key cryptography is also
called symmetric encryption.

19. Secret Key Cryptography

20. Public-Key Cryptography
Generic PKC employs two keys that are mathematically
related although knowledge of one key does not allow
someone to easily determine the other key. One key is used to
encrypt the plaintext and the other key is used to decrypt the
ciphertext. The important point here is that it does not matter
which key is applied first, but that both keys are required for
the process to work (Figure 1B). Because a pair of keys are
required, this approach is also called asymmetric cryptography.

21. Public-Key Cryptography
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22. THANK YOU....