The document discusses the significance of cryptography in securing communication over networks, emphasizing its role in protecting sensitive data from unauthorized access or alteration. It outlines various encryption techniques, such as symmetric and asymmetric cryptography, and highlights key concepts like plaintext and ciphertext. The project aims to develop a software solution for encrypting and decrypting messages and files, ensuring secure data transfer among users.

1. “Cryptography”

2. Why Cryptography ?
We all know that now a day this is the world of information technology and
almost everyone have to communicate with each other. Most of the time this
communication occurs on the network. During the communication of data it
may be possible that the data we are sending or receiving can be hacked or
edited by someone. The data we are communicating may be bank a/c number,
passwords or some important files etc. To protect the data from this type of
unwanted things “Cryptography” is very useful.

3.  This project is all about providing security while communicating any data on
the network between two or many user. We are going to discuss about the main
ciphers used in Cryptography in this project.
 There are various techniques of encryption and decryption which are used in
this project such as
 Shift or Substitution cipher
 Monoalphabetic cipher
 Playfair cipher
 Vegenere cipher
 Within the context of application-to-application communication, there are some
specific security requirements, including:
 Authentication
 Privacy/Confidentiality
 Integrity
 Non-repudiation

4.  Cryptography, then not only protect data from theft or alteration, but
can also be used for user authentication.
 There are, in general two types of Cryptographic schemes typically
used to accomplish these goal:
(1) Private–key ( or symmetric ) cryptography
(2) Public-Key ( or asymmetric ) cryptography
 In all the cases,
 The initial unencrypted data is referred to as “plaintext”.
 The encrypted data is referred to as “cipher text”.
(which will in turn (usually) be decrypted into usable plaintext)

5. 1. Introduction
1.1 Introduction to Cryptography
1.2 Types of Cryptographic Algorithm
1.2.1 Secret key Cryptography
1.2.2 Public Key Cryptography
1.2.3 Hash Function
2. Purpose
3. Objective
4. System Specification
 Hardware
 Software
5. Future Scope
6. Conclusion

6. Introduction
 The word cryptography or cryptology comes from an Ancient Greek. The word
cryptology is made of two components ”crypto”, which means hidden or secret
and “logos” which means word. It is a Science of writing in secret code.
Cryptography is the study of techniques for secure communication.
 There are two important concepts of cryptography, first one is Encryption &
the second one is Decryption. Encryption is the process in which the plain text
is changed into cipher Text & decryption is just reverse process of encryption
that means cipher text is changed into plain text. There are various techniques
of Encryption & Decryption which are used in this project such as Shift Cipher,
Playfair Cipher, Monoalphabetic Cipher, Vanier Cipher.
 We use the term cryptography to refer to the science and art for transforming
message to make them secure from attacks.

7.  The original message before being transformed is called ”Plaintext”. After the message
is transformed is called ”Ciphertext”. An encryption algorithm transform the Plaintext
into Ciphertext & a decryption algorithm transforms the Ciphertext back into Plaintext.
Encryption Decryption
#%GIUYRWKMN,S:{?
Hello World! Hello World!
( ciphertext )
( Plaintext ) ( Plaintext )
( Shared Secret Key )

8. Objective
1 . To d e v e l o p a s o f t w a r e i n w h i c h w e w i l l i n p u t :
i ) F i l e s
i i ) M e s s a g e s
a n d w e w i l l g e t e n c r y p t e d f i l e s o r m e s s a g e s .
2 . T h e e n c r y p t e d i n f o r m a t i o n c a n b e u s e d i n t h e n e t w o r k
( l o c a l o r i n t e r n e t ) i n a s a f e a n d s e c u r e d w a y
3 . T h e s o f t w a r e c a n a l s o b e u s e d t o d e c r y p t t h e e n c r y p t e d d a t a
i n t h e o r i g i n a l f o r m
4 . U s e r w i l l b e a b l e t o u s e t h e i r o w n k e y s t o e n c r y p t t h e d a t a .

9. SYSTEM SPECIFICATION
SOFTWARE REQUIREMENTS :
 OPERATING SYSTEM : WINDOWS XP / 7
 FRONT END : C#.net
 BACK END : SQL Server
HARDWARE REQUIREMENTS :
 Processor : Pentium IV & above
 Processor Speed : 1 G Hz
 RAM : 2 GB
 Hard Disc : 10 GB

10. TABLES

11. COLUMNS DATA TYPE SIZE
Member_id int
Password char 20
Security Question char 30
Security Answer char 20
L O G I N T A B L E :
(FOREIGN KEY)

12. MEMBER DETAIL TABLE
COLUMNS Data Type Size
Member_id int
Name char 20
Mobile char 10
Email_id char 30
Address Char 50
(Primary Key)

13. LOG TABLE
Columns Data Type Size
Member_id int
File name char 20
Data datetime
Type char 10
(FOREIGN KEY)
Encryption & Decryption

14. MEMBER
LOGS
IN LOGIN
History
Record
LOG
MEMBER
id
Name
Mob
no.
Email
id Password
Security
Question
Security
AnswerAddress
MEMBER
id
Member
id
File
Name
Data
Type

15. TYPES OF CRYPTOGRAPHIC ALGORITHMS
 There are several ways of classifying cryptographic algorithm.
 Defined by their application and use. The three types of algorithms that will be
discussed are as follows.
1. Secret key Cryptography(SKC)
2. Public Key cryptography(PKC)
3. Hash Function

16. SECRET KEY (SKC)
Single key used to encrypt and decrypt .
Key must be known by both parties.
Encrypt Decrypt
S a m e K e y i s u s e d t o
E n c r y p t a n d D e c r y p t d a t a
Sender
Recipient
Shared Secret
Key
Plaintext Ciphertext Plaintext

17. PUBLIC KEY (PKC)
Two different keys are used in this cryptography
One key is used for encryption & other for decryption
Encrypt Decrypt
D i f f e r e n t K e y s a r e u s e d t o
E n c r y p t a n d D e c r y p t d a t a
Sender
Recipient
Recipient Public
Key
Recipient Private
Key
Plaintext Ciphertext Plaintext

18. HASH FUNCTION
 Hash is a function which is used to compress the string.
 The input in the hash function is known as “Message” and
output is called “Digest”.
 Hash functions have four main properties :
 It is easy to compute the hash value for any given message.
 It is infeasible to generate a message from its hash.
 It is infeasible to modify a message without changing the hash.
 It is infeasible to find two different message with the same hash.
Message
( variable size )
H
A
S
H
Digest
( fixed size )

19. Our project(system) can do the cryptography by
encrypting and decrypting data. We are dependent
on other mailing systems Like – gmail, yahoo etc for
information transfer.
In future we can add the information transfer
module so that after encryption users can transfer
informationbythesamesoftware.
Future scope

20. Finally, we can say that in this
project development we have
learnt a lot and during the process
we will get the chance to explore
cryptography and the concepts
involved.
CONCLUSION