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July 28, 2017 | Author: NavpreetSinghDhunna | Category: Key (Cryptography), Public Key Cryptography, Cryptography, Encryption, Secrecy
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encryption and decryption...


CHANDIGARH UNIVERSITY, GHARUAN Department of Computer Science & Engineering B.E. CSE 7



SYNOPSIS Computerized Encryption and Decryption System

Submitted To:

Submitted By: Navpreet Singh 12bCS1176 CSE-02

Introduction 



System overview


Overall description 

Product perspective 

System Interfaces

User Interfaces

Hardware interfaces

Software interfaces

Memory Constraints


Product functions

User characteristics

Constraints, assumptions and dependencies

Specific requirements 

External interface requirements

Functional requirements

Performance requirements

Software System attributes






The main aim of Data Encryption And Decryption System Java Project is to provide the secured format between various clients in the network The Digital Encryption System is software, which tries to alter the originality of the text into some encrypted form. The major task of the Digital Encryption System is to provide the user the flexibility.

In this project we use cryptography techniques for encryption and decryption of message. While transmitting packet from source to destination we encrypt packet and transmit the packet at the receiving side decryption is done using a key that is only available to the user. When there is any data hacking at the middle of the network it is not possible to decrypt the packet. Data Encryption system project is implemented in Java Platform. We use java because it is one of the mostly used software all over the world. Java provide Serve let concept and may other features.

DEFINITIONS Encryption Encryption is the process of transforming information from an unsecured form ("clear" or "plaintext") into coded information ("cipher text"), which cannot be easily read by outside parties. An algorithm and a key control the transformation process. The process must be reversible so that the intended recipient can return the information to its original, readable form, but reversing the process without the appropriate encryption information should be impossible. This means that details of the key must also be kept secret. Encryption is generally regarded as the safest method of guarding against accidental or purposeful security breaches. The strength of the encryption method is often measured in terms of work factor - the amount of force that is required to 'break' the encryption. A strong system will take longer to break, although this can be reduced by applying greater force (the more effort that is put into the attack, the less time required to break the code). Key Management Introduction The key determines how the algorithm - the encryption process - will be applied to a particular message, and matching keys must be used to encrypt and decrypt messages. The algorithm used in an encryption system normally remains the same for the life of the equipment, so it is necessary to change keys frequently in order that identical encryption is not applied to messages for a long period. It is generally desirable to change the keys on an irregular

but managed basis. Key management deals with the generation, storage, distribution, selection, destruction and archiving of the key variables. Two basic types of encryption in use today are known as private key (also called single or symmetrical key) encryption and public (or asymmetrical) key encryption. Private-Key-Encryption In private key encryption, the same key is used for both encryption and decryption. The key must be kept secret so that unauthorized parties cannot, even with knowledge of the algorithm, complete the decryption process. A person trying to share encrypted information with another person has to solve the problem of communicating the encryption key without compromising it. This is normally achieved by programming keys into all encrypts prior to deployment, and the keys should be stored securely within the devices. In a relatively small network of encrypts, the task of key management (including key changes) is easily handled for a private key system. Private key encryption is a commonly used method of key management, and is used for standard algorithms such as DES and Triple DES. Public-Key-Encryption Public key encryption solves the problem of maintaining key security by having separate keys for encryption and decryption, which uniquely match each other but are not predictable from each other. The user retains a private decryption key and makes the public key available for use by anyone interested in sending the user sensitive information. The relationship between the keys is such that given the public key a person cannot easily derive the private key. Senders use the recipient's public key to send encrypted messages. Recipients use their corresponding private key to decrypt messages. The private key can also be used to encrypt messages, which can be decrypted by anyone with knowledge of the public key (the purpose of this is to provide verification of the origin rather than to achieve secrecy). Public key encryption is relatively inefficient and is not suitable for either encrypting large volumes or operating at high speeds. The RSA algorithm is a well-known form of public key encryption.

SYSTEM OVERVIEW Encryption of data plays a vital role in the real time environment to keep the data out of reach of unauthorized people, such that it is not altered and tampered. The digital Encryption System is software, which tries to alter the originality of the text into some encrypted form. The major task of the Digital Encryption System is to provide the user the flexibility of passing the information implementing the encryption standards as per the specification and algorithms proposed and store the information in a form that is unreadable. The Application should have a reversal process as of which should be in a position to decrypt the data to its original format upon the proper request by the user. While the Encryption and Decryption is done the application should confirm the standards of authentication and authorization of the user.

DES Encrypts and decrypts data in 64-bit block of cipher text. Since it always operates on blocks of equal size and it uses both permutations and substitutions in the algorithm, DES is both a block cipher and a product cipher. DES has 16 rounds, meaning the main algorithm is repeated 16 times to produce the cipher text. It has been found that the number of rounds is exponentially proportional to the amount of time required to find a key using a brute-force attack. So as the number of rounds increases, the security of the algorithm increases exponentially This project “DES (Digital Encryption System)” is developed on client server technology. The client encrypts the file and sends to the server. Other client will receive the file and decrypts the file by using the same private key. It is developed by java to provide platform neutral nature. It is developed in Java Swing to provide a better GUI. Java Swing provides a better look and feel.


OVERALL DESCRIPTION Product perspective System Interfaces: 1) JDBC – Java Database Connectivity (API) 2) SQL-Connector.

Hardware Interfaces: Item

Web Server

Specification Pentium P4 or equivalent processor, 1 GB RAM, 500 MB space (at least 30% of hard disk space should be empty for optimal performance)

& Database Server

Database server should have similar specifications with minimum 10MB space allocated at database creation.

Software Interfaces: OS


Application Frame work

Java Swings

Web Server





I.E 6.0 Or Above

Memory Constraints: Ram Hard-Disk

128MB (Min) 512MB (Min)

Product Functions: 1) One way encryption 2) Two way encryption 3) Hashing Techniques 4) Number system conversions

User Characteristics: We have identified five potential classifications of users of our system: 

Software Designers: These are the most obvious users. They will use the system as a means of laying out the design of an as yet unimplemented system.

Software Developers: These are the people that take the model generated by the designers and implement it in code. They may also use the system to identify the design of an existing system in order to maintain it.

Quality Engineers: These users are usually responsible for ensuring that a design is feasible and/or reliable. They will therefore also need to be looking at the output from our system.

System Administrator: Due to the client/server/concurrent nature of the system, some one needs to be responsible for security and maintenance of the system. This is the System Administrators role. The Administrator of the system, project or model need not be a member of the any of the other roles identified here.

The Client: More often than not, software is designed for a client. The client may wish to see the design as layed out by the system and be able to see what exactly they are buying.

Constraints, Assumptions and Dependencies Regularity Policies: Each user must be an authorized person.

Hardware Limitations There is no limitation in the operating system in which this system will work. However, the encryption system and the database will work on a server that needs to be always online.

SPECIFIC REQUIREMENTS External Interface requirements: Front end


Back end




Functional Requirements: 1) Encrypt plain text into cipher text. 2) Decrypt cipher text into plain text. 3) Implement Hashing techniques to store passwords in most secure form. 4) Conversion of one number system to another.

Performance Requirements: 1) Quick and Easy to use 2) Interactive User Interface 3) If exception occurs appropriate message should be displayed 4) Only numbers, alphabets, special symbols should be processed.

Software System Attributes: Reliability: All the techniques and technologies which we have used to developed this system are implemented very carefully so that it can produce correct result in a quick way.

Portability: This system is developed in Java language so you can run it on any hardware platform.

Maintainability: Java is a pure object oriented language so anytime you can add any new feature to the existing system or you can change the existing system.

BIBLIOGRAPHY Book: IT essentials by Cisco Network Academy

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