CRYPTOGRAPHY TOPIC OF THE SUBJECT COMPUTER APPLICATION (S Y B B A)

1. Presenter : Shivshankar v.
prajapati
S. Y. B.B.A.
Div -1
TOPIC :
CRYPTOGRAPHY

2. Definition of cryptography
“The techniques of
encryption and decryption
for protecting the data on a
network is known as
cryptography ”

3. Encryption Decryption
Plain text is
converted
into cipher
text is
called
Cipher text
converted
into plain
text is called
decryption

4. Encryption and
decryption

5. Encryption and decryption

6. Cipher Text
Cryptography is an art of
protecting information by
transforming it (encrypting ) into
an unreadable format , called
cipher text

7.  it is an secret writing
 Anybody can see the message , but nobody else
can read it.
 Usually , this is because its letters have been
rearranged , or replace by different letters ,
according to some scheme that only sender and
receiver know.
 Only those who posses a secret key can decipher
( decrypt ) the message into plain text

8. e.g. of cipher
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
Encrypt ( Computer ) gives frpsxwhu
Decrypt ( Frpsxwhu ) gives computer

9. A ) secret key ( symmetric ) cryptography.
Skc uses a single key for both
encryption and decryption .

10. B ) public key ( Symmetric ) cryptography
, pkc uses two keys , for one encryption
and other for decryption.

11. C ) hash function ( one-way-
cryptography ) hash function have no
key since the plain text is not
recoverable from the cipher text.
Plain
text
Cipher text
Hash function

12. Symmetric key
 This technique is also known as Secret key
Encryption decryption because the key is
used both direction.
In secret key , encryption / decryption the
same key is used by both parties
The sender uses the key for encrypt the
original data. (convert the plain text into cipher
text )

13.  The receiver uses the same key for decrypt the cipher text data
to make it in original form ( plain text ) ( convert the cipher
text to the plain text )
 As per the algorithm. The encryption algo uses a combination
of addition and multiplication . The decryption algorithm uses
a combination of division and subtraction
 Note that the secret key encryption algorithm because the
same key can be used in bidirectional communication
Continue….

14. Symmetric key diagram
Symmentric key Symmentric key

15. Advantages
1 ) Secret key algorithm are very efficient
2) it takes less time to encrypt and decrypt the
message because same key is used both sides
3) it is used for long messages

16. Disadvantages
- The distribution of keys
between two parties can be
difficult

17. Asymmetric key
• This encryption is also known as public key
encryption
• In public key encryption , there are to keys
I ) A Private Key
II ) A Public key
• The private key is kept by the receiver
• The public key is gives to the public key
receiver

18. Asymmetric key diagram

20. Advantages Disadvantages
The number of
key needed is
reduced in
this system
Public key
method is
very complex

21. THANK YOU……

22. Referenced by –
Assit. Prof. Ushma Mehta

23.  Difference between public key
and private key
 The public key is gives
to the public key
receiver
 Public key is used to
encrypt the message .
( convert the plain text
into cipher text )
 The private key is kept
by the receiver
 Private key is used to
decrypt the message .
( convert the cipher
text into plain text
public key Private key