ENCRYPTION AND DECRYPTION
TABLE OF CONTENTS
Sr. No. Title Page No.
1. Abstract 2
2. Objective and Scope 3
2.1 Objective 3
2.2 Scope 4
3. Theoretical Background 5
3.1 Existing System 5
3.2 Proposed System 5
3.3 Features 6
3.4 RSA Algorithm 7
4. Feasibility Study 9
4.1 Economic Feasibility 9
4.2 Technical Feasibility 10
4.3 Operational Feasibility 10
5. Problem Definition 11
5.1 Project Mission 11
5.2 Target 11
5.3 Target Users 11
5.4 Scope and Key Elements 12
6. System Design 13
6.1 System Design 13
6.2 Data Flow Diagram 13
6.3 Use Case Diagram 14
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ENCRYPTION AND DECRYPTION
1.ABSTRACT
The title of our project is “ENCRYPTION AND DECRYPTION”. This project
encrypts and decrypts the textual files by using RSA algorithm. Our aim is to develop
the software named ENCRYPTION AND DECRYPTION that encrypts and
decrypts the textual files by using RSA algorithm. Encryption and Decryption is a
strong text and file encryption software for personal and professional security. It
protects privacy of our email messages, documents and sensitive files by encrypting
them using RSA algorithm to provide high protection against unauthorized data
access.
Every day hundreds and thousands of people interact electronically, whether it is
through emails, e-commerce, etc. through internet. Sending sensitive messages over
the Internet is very dangerous. If you need to send sensitive messages over the
Internet, you should send it in the encrypted form. Encryption and Decryption allows
you easily encrypt and decrypt your messages. If you need to send sensitive
information via email, simply paste the encrypted text into your email and all the
recipients has to do is to decrypt the text.
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2.OBJECTIVE & SCOPE
2.1 Objective
The main objective of our project is to encrypt/decrypt the textual files for
personal and professional security. Encryption and Decryption protects privacy of
our email messages, documents and sensitive files by encrypting them using RSA
algorithm to provide high protection against unauthorized data access.
Every day hundreds and thousands of people interact electronically, whether it is
through emails, e-commerce, etc. through internet. The Internet is comprised of
millions of interconnected communication and transfer of information around the
world. People use emails to correspond with one another .The www is used for
online business, data distribution, marketing, research, learning and a myriad of
other activities.
Sending sensitive messages over the Internet is very dangerous as all emails are
transmitted in an unsecured form and anybody - ISP, your boss, etc. can read your
emails.
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ENCRYPTION AND DECRYPTION
If you want to send sensitive information via email, simply paste the encrypted
text into your email or attach the encrypted file,all the recipient has to do is to
decrypt your text or file. Encryption and Decryption works with text information
and files. Just select what you want to encrypt, and Encryption and Decryption
software helps you keep documents, private information and files in a confidential
way.
2.2 Scope
The scope of our project is presently specific.Both the sender and the receiver
must have this software installed on their systems to encrypt/decrypt and
compress/decompress the files transmitted between them.This includes all the
users who want to interact electronically, whether it is through emails,
ecommerce, etc.through internet in order to keep their private information
confidential.
Each step is clearly stated and user will not face any ambiguity in using the
software.
The software provides clarity in its functionality even to naïve users.
No complexity is involved.
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ENCRYPTION AND DECRYPTION
3.THEORETICAL BACKGROUND
3.1 The Existing System
As observed the current encryption/decryption softwares doing the encryption
and decryption task are all very complicated in their functionality.
The method of encryption/decryption and key generation of current system for a
new user to understand is complex in nature.
3.2 The Proposed System
The proposed system is quiet simple to use. It is not complex in its functionalities. It
is easy for a naïve user to use it.
If you want to send sensitive information via email, simply paste the encrypted text
into your email or attach the encrypted file, all the recipient has to do is to decrypt
your text or file.Encryption and Decryption works with text information and files.
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ENCRYPTION AND DECRYPTION
Just select what you want to encrypt, and Encryption and Decryption software helps
you keep documents, private information and files in a confidential way.
3.3 Important features of Encryption and Decryption
The system is highly user friendly.
It uses two different keys (a key pair) for encryption and decryption.These
algorithms are called "public-key" because the encryption key can be made
public. Anyone can use the public key to encrypt a message, butonly the owner
of the corresponding private key can decrypt it.
A message can be encrypted with a private key and decrypted with the
corresponding public key.If Alice (or anyone else) can decrypt a message with
Bob's public key she knows that the message must have come from Bob because
no one else has Bob's private key.
The system provides security and convenience as private keys never need to be
transmitted or revealed to anyone.
The system provides the integrity of data or information.
The software provides clarity in its functionality even to naïve users.
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ENCRYPTION AND DECRYPTION
3.4THE ALGORITHM
The RSA algorithm involves three steps, key generation, encryption and decryption.
Key Generation
RSA involves a public key and a private key. The public key can be known to
everyone and is used for encrypting messages. Messages encrypted with the public
key can only be decrypted using the private key. The keys for the RSA algorithm
are generated in the following way:
1. Choose two distinct large random prime numbers p and q
2. Compute n=pq
n is used as the modulus for both the public and private keys
3. Compute the totient: φ(n)=(p-1)(q-1).
4. Choose an integer e such that 1<e< φ(n) and e and φ(n) share no factors other
than 1 (i.e. e and φ(n) are co-prime)
e is released as the public key exponent
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ENCRYPTION AND DECRYPTION
5. Compute d to satisfy the congruence relation de≡1(mod φ(n) ; i.e., de=1+k
φ(n) for some integer k.
d is kept as the private key exponent
The public key consists of the modulus n and the public (or encryption) exponent
e. The private key consists of the modulus n and the private (or decryption) exponent
d which must be kept secret.
Encryption
Sender A does the following:-
1. Obtains the recipient B's public key (n, e).
2. Represents the plaintext message as a positive integer M
3. Computes the ciphertext C = Me mod n.
4. Sends the ciphertext C to B.
Decryption
Recipient B does the following:-
1. Uses his private key (n, d) to compute M = Cd mod n.
2. Extracts the plaintext from the message representative M.
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4.FEASIBILITY STUDY
After investigation it is essential to determine whether the project is feasible or not.
In feasibility study is tested whether the system to be developed would be able to
accomplish its task on the working grounds. Its impact was also found to be not
adverse. It was found that the user’s requirements would be met and the resources
would be used in an effective manner. In feasibility study the important aspects
related to the project were considered like the problem definition and the process for
solution. The cost and benefit analysis was also done.
4.1 Feasibility Considerations
To do a feasibility study, the economic, technical and behavioral factors in the system
development were considered.
The three key considerations were as follows:
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ENCRYPTION AND DECRYPTION
4.1.1 Economic Feasibility
The project developed, Encryption and Decryption was within budget and
producing the desired results.The labor or the human ware consisted of the
three group members of our project. The output consisted of getting the
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ENCRYPTION AND DECRYPTION
desired results. Thus with the consideration of the inputs, the outputs were
achieved successfully. The project was within limit. The inputs didn’t overdo
the outputs.
4.1.2 Technical Feasibility
Technical feasibility revolves around the technical support of the project. The
main infrastructure of the project included the project labs in the college
campus. The systems there were easily able to absorb the new s/w being
installed.The project thus was technically feasible. The equipment and the s/w
produced no problem. The project’s technical requirements were met. The
project could be made to work correctly, fulfilling its task, with the existing
s/w and personnel.
4.1.3 Operational Feasibility
Operational Feasibility aims to determine the impact of the system on the
users. The system developing has an influence on its users. Our system
“Encryption and Decryption” was new for them but it was simple enough for
any naïve person to understand. The evolution of this new system required no
special training for the users. Encryption and Decryption was found to be
feasible in this regard. The system developed would be user friendly and no
complexities would be involved in its functionalities.
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5.PROBLEM DEFINITION
5.1 Project Mission
The aim of our project is to develop software named ENCRYPTION AND
DECRYPTION.The project encrypts and decrypts the textual files using RSA
algorithm to maintain the security and integrity of data and information and
toprovide high protection against unauthorized data access.
5.2 Target
Our target is the common man who wants to interact electronically, whether it is
through emails, e-commerce, etc.through internet.Sending sensitive messages over
the Internet is very dangerous.So,our project helps him to interact in a safe and secure
manner in order to keep their private information confidential.
5.3 Target Users
The main target users of our project are the people who transmit confidential
information via emails or through internet.
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5.4 Scope and Key Elements
The scope of our project is presently specific.Both the sender and the receiver must
have this software installed on their systems to encrypt/decrypt and
compress/decompressthe files transmitted between them.This includes all the users
who want to interact electronically, whether it is through emails, e-commerce,
etc.through internet in order to keep their private information confidential.The key
elements of our website include the objectives, plus the following:
The system provides the security and integrity of data or information.
It will provide a more clear and non ambiguous description of the functions.
The system is highly user friendly.
It uses two different keys (a key pair) for encryption and decryption.These
algorithms are called "public-key" because the encryption key can be made
public. Anyone can use the public key to encrypt a message, butonly the owner
of the corresponding private key can decrypt it.
The software provides clarity in its functionality even to naïve users.
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ENCRYPTION AND DECRYPTION
6. SYSTEM DESIGN
6.1 System Design
Software design sits at the technical kernel of software engineering process and is applied
regardless of the development paradigm and the area of application. Once the system
requirements have been analyzed and specified, system design is the first of the three
technical activities- design, code and test that are required to build and verify s/w. emphasis
is on translating the s/w requirements into design specification. It involves preparing I/P-
O/P specifications, making security and control specification, and preparing a logical and
physical design work through. 6.2 Data Flow Diagram
X Y X
ENCRYPTION DECRYPTION
SENDER(A) RECEIVER(B)
ALGORITHM ALGORITHM
COMPRESSION DECOMPRESSION
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6.3 Use Case Diagram
Select a
file
Encrypt
Decrypt
Exit
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