its all about cryptography introduction ...... not at advanced level but you can know basics of what actually cryptography is ...eliminating history and going to the point

1. Cryptography
By Jai Nathwani

2. Title and Content Layout with List
• Definations
• Cryptography issues
• Cryptography components
• Cryptography technique
• Cryptography categories
Symmetric key
Asymmetric key
• Famous algorithms/ciphers

3. Definations
• Cryptography is a greek word which means secret writing.
• The term refers to art of transforming simple messages into secure messages
and secure to hackers attack.
• Applications of cryptography is ATM, text messages, passwords,e-commerce

4. Cryptography issues
• Confidentiality - only receiver must receive the message sent by sender.
• Authentication – the sender and receive must enter the id & password for
. Verifying.
• Integrity - to ensure the message is not altered in between
• Non-repudiation – means sender must not deny sending a message.

5. CRYPTOGRAPHY COMPONENTS

6. PLAINTEXT AND CIPHERTEXT
• The original message before being transformed is called plaintext
• After the message is encrypted ,it is called ciphertext
• An encryption algorithm transforms the plaintext into ciphertext; a decryption
algorithm transforms the ciphertext back into plaintext.
• Example:
• Plaintext: HELLO
• Ciphertext: KHOOR

7. KEY
• A key is a number (or a set of numbers) that the cipher operates on, as an
algorithm.
• To encrypt a message, we need an encryption algorithm, an encryption key, and
the plaintext.
• To decrypt a message, we need a decryption algorithm, a decryption key, and the
ciphertext. These reveal the original plaintext.
• Types:
• Public key and Private key.

8. CRYPTOGRAPHY CATEGORIES

9. CRYPTOGRAPHY CATEGORIES
• We can divide all the cryptography algorithms (ciphers) into two groups:
• Symmetric key (also called secret-key) cryptography algorithms
and
• Asymmetric key (also called public-key) cryptography algorithms

10. SYMMETRIC KEY CRYPTOGRAPHY
• In symmetric-key cryptography, the same key is used by both parties.
• The sender uses this key and an encryption algorithm to encrypt data; the
receiver uses the same key and the corresponding decryption algorithm to
decrypt the data.

11. aSYMMETRIC KEY CRYPTOGRAPHY
• In asymmetric or public-key cryptography, there are two keys: a private key and a
public key.
• The private key is kept by the receiver.
• The public key is announced to the public.
• If “A” wants to send a message to “B”, “A” uses the public key to encrypt the
message. When the message is received by “B”, the private key is used to
decrypt the message.

12. Symmetric asymmetric
Only 1 shared key is involved 2keys-1)public
2)private
Same key is used to encrypt and decrypt Encryption-public
Decryption-private
The key is kept secret between users Private key is kept secret..
Public key is made public.

13. This was theoretical concept
lets move on practicality…
where not only me, not only you…but each
n everybody applies cryptography in real
life..{*from my point of view}