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
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