Simple Presentation on cryptography

1. -Deepti Sakpal

2. Security Threats
Modify
messages in
transmit
Replay
previous
messages
Masquerade of
one entity as some
other
Obtain
message
contents
Monitoring
traffic flows
Denial of
service
Passive Threats Active Threats

3. What is Cryptography?
 Cryptography is a method of protecting information and communications
through the use of codes so that only those for whom the information is
intended can read and process it.
 The pre-fix "crypt" means "hidden" or "vault" and the suffix "graphy" stands for
"writing.“
 It provides Confidentiality, Integrity, Accuracy, Authencation.
Secure
Accuracy
Integrity
Confidentiality
Authentication

4. Categories of Cryptography
Cryptography
Symmetric
Cryptography
AES
(Advanced Encryption
Standard)
Asymmetric
Cryptography
DSA
(Digital Signature
Algorithm)

5. Encryption & Decryption
• Encryption
The process of converting plain text into an unintelligible format (cipher
text) is called Encryption.
• Decryption
The process of converting cipher text into a plain text is called Decryption.
 What is a Key
In cryptography, a key is a variable value that is applied using an
algorithm to a string or block of unencrypted text to produce encrypted
text, or to decrypt encrypted text. The length of the key is a factor in
considering how difficult it will be to decrypt the text in a given
message.

6. Symmetric Cryptography
 Also known as secret key cryptography. Sender & receiver uses same key & an
encryption/decryption algorithm to encrypt/decrypt data. i.e. the key is
shared.
Encryption Decryption
Secret Key
Cipher Text
• Advantages
1. Simpler and Faster
• Disadvantages
1. Less Secured
Plain Text Plain Text

7. Asymmetric Cryptography
 Also known as public key cryptography. Sender & receiver uses different keys for
encryption & decryption namely PUBLIC & PRIVATE respectively
Encryption Decryption
Public Key Private Key
Cipher Text
• Advantages
1. More Secured
2. Authentication
• Disadvantages
1. Relatively Complex
Plain
Text
Plain
Text

8. Comparison
Symmetric Cryptography Asymmetric Cryptography
1) The same algorithm with the same key
is used for encryption and decryption
1) One algorithm is used for encryption and
decryption with a pair of keys, one for
encryption and one for decryption.
2) The key must be kept secret. 2) One of the two keys must be kept secret.
. 3) It may be impossible or at least
impractical to decipher a message if no
other information is available.
3) It may be impossible or at least
impractical to decipher a message if no
other information is available.

9. Applications
 Defence services
 Secure data manipulation
 E –commerce
 Business transactions
 Internet payment systems
 User identification systems
 Access control
 Data security

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