CHAPTER ONE

INTRODUCTION

Project Overview

As a result of the rapidly growing use of networks and their

interactions with all types of other networks (often on a worldwide basis), the problem of

protection the confidentiality and integrity of the information transmitted on these networks

started to attract widespread attention in the late 1970’s and early 1980’s. Local area networks

provided many user access points. Since a feature of LANs is that additional accesses points can

be easily added without having any effect on other network users, an authorized person to gain

access to proprietary of classified information could use these connections. To protect both

equipment and information, network security must consider a wide range of administrative,

physical, and technical issues. To select an appropriate set of network security measures, one

first needs to evaluate the threat environment and assess the security techniques can be selected

and applied

Client Information.

Galaxy Software solution is an ISO 9001: 2000 certified Offshore outsourcing Company

Headquartered in Hyderabad - India providing IT services for SMEs (Small and Medium

Enterprise) for the past Seven years.

 Galaxy Software solution empowers global innovators with sophisticated

outsourcing solutions. From product development, to application outsourcing, through

globalization and cutting-edge business process solutions, we enable our clients to decrease

costs, improve operations, and dominate their global markets. Our clients utilize Galaxy

Software solution's world-class processes and best practices for uncompromised quality and

efficiency. They leverage Galaxy Software solution's vast network of relationships to propel their

business operations globally and accelerate innovation

Aims and Objectives

To keep information out of unauthorized users we have to maintain Secrecy.

Confirmation pact with decisive we must have to know with whom you are

talking to previous to illuminating sensitive information.

Non refutation deals amid signatures

INTEGRITY CONTROL

To design a secure system for the clients to transfer their valuable information

to their destinations.

To research existing literature relating to different approaches to network

security.

Writing dissertation with full detailed of developing process.

Evolution of the project.

Research methodology

1. For booming achievement of this project to meet my client’s necessities, a thorough

investigate on encryption technology and several encryption methodologies will be

carried out Network design approach will be researched. The research will be perform

utilizing research journals, textbooks, technology white papers, and talk with program

lecturers. Most of the resources utilized were taken from online research sites like

sciencedirect.com, techrepublic.com, findwhitepapers.com and ACM.com. The

obtainable system comprises of files with literally no file security standards like

encryption techniques are to be put into practice due to the factors such as Reading or

tapping data, Manipulating and modifying data, Unlawful use of files, Corrosion of data

files, Distortion of data transmission, Disturbance of the operation of equipment or

systems, adjacent to which numerous security actions had to be taken up, The core

concern of (1) is secrecy and confidentiality. Confidentiality has always played an vital

role I diplomatic and military matters. Often Information ought to stored or transferred

from one place to another devoid of being exposed to an rival or enemy. Key

management is also associated to confidentiality. This deals with generating, distributing

and storing keys.Items (2-4) are mainly concerned with reliability. Often the expression

integrity is utilized as a gauge of genuineness of data. Also Computer files and networks

must be secluded against intruders and Unauthorized. Items (5-6) are a diverse aspect of

the security of the information, its continuity. Here the information must be secluded

against deliberate disruption at the time of its transmission and storage.

Content Information

This research write up contains a total of five chapters with references and appendices that support the entire dissertation. The following are a list of chapters with its corresponding contents

Chapter Two: This chapter specifies the difficulty that occurs during transfer of data into

different types of networks and the need to utilization of encryption.

Chapter three:This study covers the detail description of encryption and its

functionalities.

Chapter four: The entire description about the how the text is converted into a coding

format which cannot be understand by the individual.

Chapter five: It describes then properties of the algorithms’ and best conditions for their

enhanced performance.

Chapter seven: Data encryption standard and it deals with how the data is encrypted from

step to step.

Chapter eight: It describes the blow fish algorithm and it is a symmetric block cipher that

can be effectively used for encryption and safeguarding of data.

Appendices

References

CHAPTER-2

NETWORK SECURITY

As a result of the rapidly growing use of networks and their interactions with all types

of other networks (often on a world wide basis), the problem of protection the confidentiality and

integrity of the information transmitted on these networks started to attract widespread attention

in the late 1970’s and early 1980’s. Local area networks provided many user access points.

Since a feature of LANs is that additional access points can be easily added without having any

effect on other network users, an authorized person to gain access to proprietary of classified

information could use these connections. To protect both equipment and information, network

security must consider a wide range of administrative, physical, and technical issues. To select

an appropriate set of network security measures, one first needs to evaluate the threat

environment and assess the security techniques can be selected and applied.

Problems of Network security can be diverged into area:

1. Secrecy

2. Authentication

3. Non-repudiation

4. Integrity control

SECRECY

The main aim of Secrecy is to keep away information from hands of unofficial

users. It usually comes to mind when people imagine basing on network security.

AUTHENTICATION

Confirmation pact with decisive we must have to know with whom you

are talking to previous to illuminating sensitive information.

NON REPUDIATION

Non repudiation agreement with signatures.

4. INTEGRITY CONTROL

It compact to be confident that a message you received was actually the one sent

and not any other thing that a wicked adversary altered in transit or concocted

2.2 APPROACHES TO NETWORK SECURITY

Secure communication in physically vulnerable networks depends on the

disciplines of cryptography to guard the privacy and integrity of material passing between

machines. Cryptography is a tactic for altering the depiction or look of a message through a

location – scrambling process or throughout a few method of transformation of letters or

characters devoid of changing its in order content. To see where security fits into a

communication network consider a seven-layer OSI Reference Model, it is usually only

implemented in several of them . The two fundamental approaches to communication security

are link –oriented and end –to- end encryption measures. As its name implies, link-oriented

security measures protect message traffic transient over an individual transmission link among

two nodes, regardless of the original source and the ultimate target of that information. The

general scheme is shown in a 1.2 where encryption is performed independently on each

communication link between successive modems. The encryption is done by means of a function

called a Key. Each link corresponds to a data-link layer association in the OSI Reference Model.

An advantage of link-oriented security is that, depending on the

encryption method used , it can mask origin-to-destination information flow patterns and can

Totally avoid all forms of traffic analysis by hiding message frequency and length patterns, but

the weakness is that as information is encrypted merely on the links, the network nodes must be

both physically secured and capable of isolation information from each of various independent

data streams the could pass through the node. In contrast to this protection of individual links,

end-to-end security uniformly protects each message along its entire route from source to

destination as is shown in A1.3

Thus messages pass through the entire network of transmission links, local computers,

intermediate nodes switches in an encrypted form as provided by encryption device at the

message originator.

As the network layer, for keeping packets in or keep packets out Firewalls

can be installed. Coming to transport layer, whole relatives can be encrypted end-to-end, such as

process to process. Even though these solutions aid with secrecy concern and several people are

running hard to perk up them, no one of them crack the authentication or non-repudiation trouble

in satisfactorily general way. To undertake these problems, the solutions must be in the

application layer, which is why it led to later chapters.

CHAPTER-3

ENCRYPTION AND DECRYPTION

Encryption

Encryption is the procedure of renovating information from an unsecured form into coded

information, where the information cannot be understand by the outside person. An algorithm

and a key control the transformation process is controlled by algorithm and a key. 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 potentiality of the functionality is calculated in terms of work-factor-the strength

of that is necessitate to ’break’ encryption. A strengthened system will with stand for a long time,

even though by giving great force can reduce this.

The main characteristics of private key cryptosystem is as follows:

1) For both encryption and decryption the same private key is used In encryption. The

key is been in secrecy so that no other intruder can does not have a chance to know

about the knowledge of the algorithm. absolute the decryption process.

2) After the encryption takes palce, the next main division is the decryption, In this

process the code is again converted back to the original code, And in this way the

whole at the entire process of file transfer is carried out. And destination client will

be in favor of receiving the original text, So the decryption acting a crucial role in

this project.

2.2 Problem Definition

The primary troubles that are discussed in APTS, that commonly work on projects projects

that deal with communication, are given below in detail.The necessitate of the hour was to

perform algorithms like Rijndeal and the refuge over the data transmitted could be secure. And

the next factor was the performance efficiency that this algorithm supported.

Ways and Sources of File Threats

1) Unauthorized Access

“Unauthorized access” it is the way that an intruder can get permit to enter into the

machine and access the unauthorized files. The goal of these type of attack is to admission

some resource that your machine should not facilitate the attacker.

2) Executing Commands Illicitly

It’s perceptibly adverse for an not known and untrusted person to be capable to execute

commands on your server machines. The sternness of the problem is of two types problem:

first one is user access, and the next one is administrator access.A general user can perform so

many things on the system such as read files edit them.and these things that an cannot

perform.

Subsequently that an attacker can might perform configuration alterations to the host like

changing the port number of the host system an d make the system shutdown so that the

system can shut down every time as it is started.To perform this type of actions first the

intruder has to get access of the administrator previliges.

3) Confidentiality Breaches

There suppose we assume that there is data that which is very confidential if that data is fell in

the hands of intruder there may be a chance of modifying the data or he can change the entire

data or he can replace the old data with new dataIn such type of situations the general user

accounts on the system is enough to make damage against the company.

As several intruders of these types of break-ins are merely thrill-seekers and they do not

have interest in nothing to see a shell prompt for your computer on their screen, these are

highly malicious.

4) Destructive Behavior

Among the destructive sorts of break-ins and attacks, one of the two major categories is.

Data Destruction.

Some of the intruders are those who want to delete the things which there aim is to data

destruction. In this situation, the bang on the computing competence—and accordingly the

business – cannot be less than if a fire or any other natural calamity takes place so that other

disaster caused your computing equipment to be completely destroyed.

2.3 Solution to the problem

File Security

The primary thing that we think about the file is it’s security and we make the file to rid out

of the problems that are discussed as above for that we have to perform file security.problems

given above like execution of commands illicitly, unauthorized access, confidentiality

breaches and destructive behavior. The subsequently chief area is cryptography.

Cryptography

Cryptography is a division of Cryptology. The word Cryptology is derived from greek word

‘cruptos’ which resemblances hidden and logos study and the combination of this two words

gives cryptology. And this word fairly represents the science of concealing. It consists of

techniques for ,in the same way to decrypt the messages and signals. And the Cryptology can be

classified into two areas: Cryptography and Cryptanalysis.

Assume a user wants to encrypt a file just aaa.txt and given a password as “srinvas”. Since

the file as achieved to get the features so that it can store by itself, the password that which we

are given will also be stored somewhere in the encrypted file in the encrypted form. Suppose

the intruder may try to open the file eh don’t understand nothing as the file is already

encrypted form. This is one type of hiding password in a file . In this way the password can be

hidden into a file devoid of a necessitate of any database. In the same way as the user wants to

decrypt the file, he should facilitate the identical password as that of encryption.

Private-Key-Encryption

Coming to private key encryption the identical key is utilized for encryption and decryption.And

the key must be kept secrecy so that even the intruder with about the algorithm can 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 encrypt 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.

Key Management

There are three basic elements in any encryption system:

-- a means of changing information into code (the algorithm);

-- a secret starting point for the algorithm (the key); and

-- a system to control the key (key management).

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 pact 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.

CHAPTER-4

ENCRYPTION BASICS

“It may well be doubled whether human ingenuity can construct an enigma of the kind which

human ingenuity may not, by proper application, resolve”.

-Edgar Allen Poe, The Gold Bug

4.1 INTRODUCTION

This chapter presents basic concepts and terminology for constructing encryption systems. The

following topics are described:

1. Types of Ciphers, algorithms and modes.

2. How encryption system fails.

3. How to recognize adequate Crypto: algorithms and modes.

4.2 ENCRYPTION BUILDING BLOCKS

A modern devices of crypto has many essential elements that agree on how it

works. Firstly in crypto algorithm, Which mainly consider mathematical transformation that

worked out on data to encrypt or to decrypt it. To encrypt a digital data stream a bit at a time

stream cipher are used. The well-known algorithms, however, are for Block ciphers, which

transform data in fixed-sized blocks, one block at a time. When block ciphers are applied block

by block to the data stream. The fundamental encryption and decryption processes are depicted

in A1.1. The functionality of encryption consists of two inputs, and one of them is known as

plain text and second one is key. The key consist of a finite number of bits, which are usually

expressed as decimal, hexadecimal, or alphanumeric character strings.

4.2.1 TRANSPOSITION CIPHERS

Transposition ciphers are based on the rearrangement of each character in

the plain text message to produce a cipher text. The encryption techniques include reserving the

entire message, reforming the message into a geometrical shape, rearranging the plain text by

scrambling a sequence of columns, and periodically permuting the characters of the plain text.

Let us now look at simple examples to illustrate this.

1. Message Reversal:

In this method the plain text is written backwards to produce a cipher text.

If the plain text message is:

LOCAL AREA NETWORKS SECURITY

Then the encrypted message reads

YTIRUCES KROWTEN AERA LACOL.

This is one of the simplest encryption methods. Obviously, it is not very secure, since to do

decipher it one merely reads the cipher text in reverse.

2. Geometrical Pattern Encoding:

In this method the message is rearrange with the aid of some type of

geometric figure, a typical example being a two-dimensional array or matrix. First the plain text

is written into the figure according to particular pattern. Taking the letters off the figure

according to a different path then creates the cipher text.

Example:

The plain text word is written into a

3 X 5 matrix by rows as follows

Column number 1 2 3 4 5

Cipher text V A R C H

E K N S K

H L Y D T

If columns in the order 24155 take off the letters, the resulting cipher is

HLRESCVANKVDKH.

3. Columnar Transposition

In this method, one first transpose the plain text message into a rectangular

form by columns. The columns are next rearranged and the letters are taken off in a horizontal

fashion.

Example:The plain text message “The product Brochure is Ready”, which we write into

5 X 5 matrix by columns as follows

Column number 1 2 3 4 5

Cipher text T O B U R

H D R R E

E U O E A

P C C I D

R T H S Y

Since there are five columns, that can be rearranged in 5! = 120 different ways. To enhance the

security of the plain text message, we can thus choose one of these rearrangements

A drawback in using columnar transposition ciphers for computer applications is that entire

matrices of characters must be generated to encryption and decryption.

4.2.2 SUBSTITUTION CIPHERS

Substitution enciphering involves the replacement of each character in the

plain text by some other character. This can be a letter , a number, or a symbol. The four basic

classes of substitution ciphers are as follows:

1. Simple Substitution

A corresponding character of cipher text replaces each character of plain text; a single one-to-one

mapping from plain text to cipher text is used to encrypt and entire message.

2. Homophonic Substitution

Each plain text character is encrypted with a variety of cipher

text characters. The mapping from plain text to cipher text is thus one-to-many.

3. Polyalphabetic Substitution

Multiple Cipher alphabets are used to change plain text to cipher text; the mappings are usually

one-to-one as in simple substitution, but can change within a single message.

4. PolyGram Substitution

These are the most general ciphers; they permit arbitrary substitutions for groups of plain

text characters. For illustrative purposes, we only discuss simple substitution ciphers here.

Suppose A is a plaint text n-character alphabet ordered us look as {a0,a1,…….an-1}. A

simple substitution cipher then replaces each character of A by a corresponding character from

an ordered cipher alphabet C denoted by {f(a0),f(a1),f(a2),……….f(an-1)}. Here the function ‘f’

represents a one-to-one mapping of each character of A to the corresponding character of C.

A plain text message

M=m1m2m3 …….

is then written as Ek(M) = f(m1)f(m2) …….

Where mi is a character of A. Typically C is simply a rearrangement of the characters in A.

4.2.2 PRODUCT CIPHERS

A product cipher involves a combination of transposition ( permutation) and substitution

to produce a cipher text. The products are of the form B1MB2M…….Bn where M is an un-

keyed mixing transformation or permutation and the B1 are simple cryptographic transformation.

Thus , a product cipher is the application of sequence of ‘n’ enciphering functions f1,f2,…….fn

where each f1 can be a permutation cipher P or a substitution cipher S . A1.2 illustrated the

application of the basic principle to a 12-bit message block .

M= ( m1m2........m12) .we should note that this example is for concept illustration purpose

only , since in practice longer locks should be used .The enciphering scheme alternately applies

‘k’ substitution Si and ‘k-1’ permutations Pi yielding

C= Ek (M) =SkPkSk-1………..S2P1S1 (M)

The plain text of 12 bit is make parts into 3-bit sub block each performs as a diverse invertible

substitution cipher kij which results in 12 bit are scramble by the permutation box Pi and it acts

as the input to coming round of enciphering. This blend bits diverse dij boxes for the reason

devoicing overall transformation from degeneration and making them to place in 3-bit block.

.2.3 BLOCK CIPHERS

Block ciphers involve encrypting and decrypting messages in blocks of information bits.

Given that M is a plain text message, a block cipher breaks M into successive blocks M1, M2 …

and enciphers each Mi with the same key K, i.e. Ek (M) = Ek(M1)Ek(M2) .. . The basic

concept of block ciphering with partitioning and iteration is shown in A3.1. A block of message

to be transformed iteratively I=1,2,….r times is divided equally into halves denoted as Li and

Ri. If the block is n bits long , then Li and Ri each have n/2 bits. Encryption and Decryption is

carried out by means of the set of iteration- dependent keys Ki+1 and a transformation function

f. This transformation function depends on Ri and Ki+1 for encryption and on Li+1 and Ki+1

for decryption.

As shown figure A2.5 for the (i+1)th iteration the encryption yields

Li+1=Ri

Ri+1=Li(mod-2)f(ki+1,Ri)

For decryption the of Ki+1 is reversed,

i.e. Li=Ri+1 (mod-2)f(Ki+1,Li+1)

Ri=Li+1

When block ciphers are applied to data stream, the cipher mode defines how the algorithm is

applied block by block to the data stream.

4.3 How Cryptosystems fail

Networking systems fail to protect messages because people are motivated to attack

them. Typical data communication protocols are designed to deal with random errors:TCP/IP

delivers data reliably even when a broad range of accidents and failures occur. But these

protocols aren’t designed to stand up against conscious attempts to fool them

Unlike generic communication protocols, cryptosystems are designed to stand up against

attack. When cryptosystems do fail, we can identify weakness as failing into either of two

categories: in the cipher itself or in the operating environment. The cipher itself is the mechanism

by which a given message is transformed from plain text into cipher text. The environment in

which the code is used includes the rules for handling plain text, the distribution of keys, the

roles of people involved, and the physical protections given to the various elements.

A very trivial example illustrates the basic concepts of a “weak” code consider the codes

used for cryptograms published as puzzles in news papers. Typically, cryptograms use very

simple encryption techniques that can be cracked by applying some basic rules.

Here is a classic:

SEND

+MORE

=MONEY

We can tell that the solution requires a substitution of letters for digits by the way the problem is

presented. We can immediately identify the letter standing for one digit based on the rules of

arithmetic: M must stand for 1. Systematic trail and error quickly yields the rest of the code. This

is perhaps the easiest example there is of cryptanalysis-the systematic breaking of the encrypted

messaged and coding systems.

Cracking a code involves either an attack on the code itself or on the way the code is

used. Given the strength of modern codes, the real risk today is in how they are actually used.

However, it is still important to select an appropriately strong alternative from the number

available in today’s market place.

The essential objective is choosing a strong code, or a strong cryptosystem for that matter

is to look at the work factor it presents an attacker. The work factor is an estimate of how hard

the attacker must work in order to by pass the protection and achieves valuable goal. Stronger

systems present a larger work factor while weaker systems are easier to overcome. Ideally the

work factor should be large enough to make the cost of an attack greater than the potential

benefits to the attacker.

4.4 CHOOSING BETWEEN STRONG AND WEAK CRYPTO

The advice any one would desire at this point is an ordered list of the technologies known

to be the strongest. Unfortunately, it is difficult to choose reliably that way. Not all crypto

products support all strong algorithms or modes, or provide comfortably long key lengths. and

what those problems are then when faced with a product containing a particular problem, we can

decide if the risk is acceptable for out application In any case, prudent planners will anticipate

hoe their system can migrate to a different crypto mechanism and key length in the future. No

security technology remains effective forever.

CHAPTER-5

CRYPTO ALGORITHM PROPERTIES

5.1PROPERTIES OF GOOD CRYPTO ALGORITHM

Preferred algorithms generally have the following properties to some degree.

5.1.1 NO RELIANCE ON ALGORITHM SECRECY

While it may, in some cases, increase the attacker’s work factor to keep as much secret as

possible, keeping a crypto algorithm secret can be a double-edged sword. If we don’t know how

the algorithm works- we can’t tell if it has some easy-to-exploit flaw.

Good crypto algorithms rely exclusively on keys to protect the data. Revealing the

algorithms should not significantly improve an attackers likelihood of success.

5.1.2 NO RELIANCE ON ALGORITHM

The algorithm should have been designed in the first place to resist crypt analysis. This is

not always true of algorithms used for encryption. For example, some products use simple

random number generators to produce a venom cipher key stream. Simple notations of statistical

randomness do not guarantee strength against crypt analysis.

5.1.3 AVAILABLE FOR ANALYSIS

Ideally, the algorithm had been published and subjected to scrutiny by the public

cryptographic community. The longer mathematicians and crypt analysts have to look at the

algorithm, the more likely they will find its weaknesses. DES has stood the rest of time and is

likely to be used for many years to come in some form or other.

5.1.4 SUBJECT TO ANALYSIS

Have recognized cryptanalysis published results regarding the algorithm strength?

Ideally, recognized experts should be openly discussing the algorithms and other experts review

publishing analysis in referred professional journals that ensure the work. This almost never

occurs except in cases when the algorithm itself has been published. It is always important to

judge the experts rendering the opinion: are they within their scope of expertise?

5.1.5 NO PRACTICAL WEAKNESSES

The analysis performed should show that there are no serious weaknesses in the

algorithm that an attacker can easily exploit. Custom-built algorithms embedded in commercial

software tend to have serious weaknesses if a commercial package claims to encrypt data and

does not use a recognize algorithm, do not presume that it protect against any motivated attacker.

Implementing Rijndeal

Notation and Conventions

Rijndael Inputs and Outputs

First the plain text is written into the figure according to particular pattern. Taking the letters

off the figure according to a different path then creates the cipher text.columnar TranspositionIn

this method, one first transpose the plain text message into a rectangular form by columns. The

columns are next rearranged and the letters are taken off in a horizontal fashion. Since there are

five columns, that can be rearranged in 5! = 120 different ways. To enhance the security of the

plain text message, we can thus choose one of these rearrangements. A drawback in using

columnar transposition ciphers for computer applications is that entire matrices of characters

must be generated to encryption and decryption Substitution cipher. Substitution enciphering

involves the replacement of each character in the plain text by some other character.

Bytes

A byte in Rijndael consists of a set of 8 bits and this is the general source for all cipher

operations. And this type of bytes are construe as restricted field elements utilizing polynomial

representation, like as a byte b with b0 b1 … b7:

The values of bytes will be presented in binary as a concatenation of their its (0 or 1) between

braces. Hence {011000011} identifies a exact limited field element. If not particularly indicated,

bit patterns will be obtainable with higher numbered bits to the left. It is also suitable to denote

byte values utilizing hexadecimal notation, with each of two groups of four bits being signify by

a character as Follows.

Hence the value {011000011} can also be written as {63}, where the character signify the 4-

bit group containing the higher numbered bits is again to the left.

Few finite field operations utilize a single additional bit (b8) to the left of an 8-bit byte. Where

this bit is there it will come out immediately to the left of the left brace, for example, as in 1{1b}.

Arrays of Bytes

Entire input and out put are taken as single dimentional arrays of bytes at which x consists of

bits 8x to 8x+7 from the sequence with bit 8x+j in the succession map to bit 7-j in the byte for 0

<= j < 8. And the sequence is represented by symbol b and x is represented for two notations as

well as two representations bx or b[x], with x in one of the ranges 0 <=x < 16, 0 <=x < 24 or

0 <=x < 32.

The Rijndael State

The performance of Rijndael operates on a two dimensional array of bytes known as state

which comprises of Xc-columns and 4-rows and Xc is primary supply which is of length 32.And

array is denoted by symbol k, and each and every byte is split into 2 indexes:its row number p

with on the , in the range 0 <=p < 4, and its column number c, in the range 0 <=l < Nc, hence

allowing it to be referred to either as l p k , or s[r, c]. For AES the range for c is 0 <=l < 4

where since kc as static value of 8.Comming to the encryption and decryption functions the

entire descryption as shown in the figure 1

Basing on the scheme at the initial of encryption or decryption the input array in is copied to the

state array according to the scheme:

s[r, c] = in[r + 4c] for 0 £ r < 4 and 0 £ c < Nc

Arrays of 32-bit Words

The four bytes in each column of the state can be thought of as an array of four bytes indexed

by the row number r or as a single 32-bit word (bytes within all 32-bit words will always be

enumerated using the index r). The state can hence be considered as a one dimensional array of

words for which the column number c provides the array index. The key schedule for Rijndael,

described below, is an array of 32-bit words, denoted by the symbol k, with the lower elements

initialized from the cipher key input so that byte 4i+r of the key is copied into byte r of key

schedule word k[i]. The cipher iterates throughout a numeral of cycles, called rounds, each of

which utilizes Nc words from this key schedule. Hence the key schedule can also be viewed as

an array of round keys, each of which consists of an Nc word sub-array. Hence word c of round

key n, which is k[Nc * n + c], will also be referred to using two dimensional array notation as

either k[n,c] or kn,c . Here the round key for round n as a whole, an Nc word sub-array, will

sometimes be referred to by replacing the second index with ‘-’ as in k[n,-] and - , n k .

Finite Field Operations

Finite Field Addition

The addition of two finite field elements is achieved by adding the coefficients for

corresponding powers in their polynomial representations, this addition being performed in

GF(2), that is, modulo 2, so that 1 + 1 = 0. As a result, addition and subtraction are equally

equivalent to an exclusive-and operation on the bytes that symbolize field elements. Addition

operations for limited field elements will be denote by the symbol Å. For instance, the

subsequent expressions are equivalent:

(polynomial notation)

{01010111} Å {10000011} _ {11010100}

(binary notation)

{57} Å {83} _ {d4}

(Hex Notation)

Finite Field Multiplication

A simple substitution cipher then replaces each character of A by a corresponding

character from an ordered cipher alphabet C denoted by {f(b0),f(b1),f(b2),……….f(bn-

1)}. Here the function ‘f’ represents a one-to-one mapping of each character of B to the

corresponding character of C. A plain text message N=n1n2n3 ……. is then written as

Ek(n) = f(n1)f(n2) ……. Where mi is a character of B. Typically C is simply a

rearrangement of the characters in B.Product cipherA product cipher involves a

combination of transposition ( permutation) and substitution to produce a cipher text.

The products are of the form C1MC2N…….Cn where N is an un-keyed mixing

transformation or permutation and the C1 are simple cryptographic transformation. Thus ,

a product cipher is the application of sequence of ‘n’ enciphering functions f1,f2,

…….fn where each f1 can be a permutation cipher P or a substitution cipher S . A1.2

illustrated the application of the basic principle to a 12-bit message block . M=

( m1m2........m12) .we should note that this example is for concept illustration purpose

only , since in practice longer locks should be used

Since this polynomial has powers of x up to 8 it cannot be represented by a single byte and

will be written as either 1{00011011} or 1{1b} as indicated earlier. This process is illustrated in

the following example of the product {57} · {83} _ {c1} (where · is used to represent finite field

multiplication):

This intermediate result is now divided by m(x) above:

Multiplication is associative, and there is a neutral element {01}; for any binary polynomial b(x)

of degree less than 8, the extended Euclidean algorithm can be used to compute polynomials a(x)

and c(x), such that:

Which shows that the polynomials a(x) and b(x) are mutual inverses. Furthermore:

It hence follows that the set of 256 byte values, with the XOR as addition and multiplication as

clear above has the structure of the limited field GF(256).

Multiplication by Repeated Shifts

The unlimited field facet 00000010 is the polynomial y, which represents with the next

element by the value augment all its power y by 1. It move byte by position 1 to the position

i+1. In case where the highest bit as given top most preference and it will flow over y8 term,and

for cancelling additional bit modular polynomial is added, where the outcome that suits within a

single byte. For instance, multiplying 10001000 by x, that is 00000010, the preliminary result is

1{10010000}.The bit that is extra is removed by supplementary one, the modular polynomial,

using an exclusive-or operation is used in modular polynomial to get the final outcome .

Due to replicate this process, a finite field element can be multiplied by all powers of x from

0 to 7. Multiplication of this element by any other field element can then be achieve by addition

the outcome for the appropriate powers of x. For instance, Table 1 carries out this calculation for

the product of the field elements {57} and {83} to give {c1}.

Finite Field Multiplication Using Tables

While it may, in some cases, increase the attacker's work factor to keep as much secret as possible,

keeping a crypto algorithm secret can be a double-edged sword. If we don't know how the algorithm

works- we can't tell if it has some easy-to-exploit flaw. While it may, in some cases, increase the

attacker's work factor to keep as much secret as possible, keeping a crypto algorithm secret can be

a double-edged sword. If we don't know how the algorithm works- we can't tell if it has some easy-to-

exploit flaw. Good crypto algorithms rely exclusively on keys to protect the data. Revealing the

algorithms should not significantly improve an attackers likelihood of success. While it may, in some

cases, increase the attacker's work factor to keep as much secret as possible, keeping a crypto

algorithm secret can be a double-edged sword. If we don't know how the algorithm works- we can't

tell if it has some easy-to-exploit flaw. Good crypto algorithms rely exclusively on keys to protect the

data. Revealing the algorithms should not significantly improve an attacker likelihood of success.

Good crypto algorithms rely exclusively on keys to protect the data. Revealing the algorithms should

not significantly improve an attackers likelihood of success. . The longer mathematicians and crypt

analysts have to look at the algorithm, the more likely they will find its weaknesses. DES has stood

the rest of time and is likely to be used for many years to come in some form or other.

By using Rijindeal we get the following tables in this table using the previous instance shows

For the Rijndael field [4] is a generator[57] equals [05][54] and [76] = [69][20]where the braces

The unlimited field facet (62) + (50) = (b2) is the polynomial y, which represents with the next

element by the value augment all its power y by 1. It move byte by position 1 to the position

i+1. In case where the highest bit as given top most preference and it will flow over y8 term,and

for cancelling additional bit modular polynomial is added, where the outcome that suits within a

single byte. For instance, multiplying by x, that is the preliminary result is {57} · {83} = {03}

(62) + (50) The bit that is extra is removed by supplementary one, the modular polynomial, using

an exclusive-or operation is used in modular polynomial to get the final outcome .

Polynomials with Coefficients in GF(256)

Four term polynomial is represented as follows:

Four term polynomial is represented as fields with fine number of elements where as the four

term polynomial generally consists of four coefficients which each coefficient represented by a

byte and consists the bytes in the form of 32-bytes word.

We have to perform so many application for the permutations and combinations like to perform

addition and multiplication which these operations can be performed by some mechanizes that to

perform some operations such as like addition can be performed for this we have to perform by

accumulation the finite field coefficients such as identical powers which relates to xor function

which corresponds to their appropriate bytes and sis of 32-bit of x,and the same way the other

operation can be multiplication this can be attained by algebraically growing the polynomial

product and amass like powers of x to give:

where:

. In Rijndael the polynomial used is x4 + 1. For instance, multiplying by x, that is the

preliminary result is A for a.b. The bit that is extra is removed by supplementary one, We have to

perform so many application for the permutations and combinations like to perform a addition

(XOR and multiplication which these operations can be performed by some mechanizes that to

perform some operations such as polynomial coefficients:

:

If one of the polynomials is fixed, this can conveniently be written in matrix form as:

For the reason that x4+1 which is not educable and each and every polynomial

multiplications are invertible. For Rijndael, though, a polynomial that has an inverse has

been chosen:

For Rijndael, polynomial has to inverse has been chosen basic classes of substitution ciphers are

as follows Simple Substitution A corresponding character of cipher text replaces each character

of plain text; a single one-to-one mapping from plain text to cipher text is used to encrypt and

entire message. Homophonic Substitution Each plain text character is encrypted with a variety of

cipher text characters. The mapping from plain text to cipher text is thus one-to-many

Polyalphabetic Substitution Multiple Cipher alphabets are used to change plain text to cipher

text; the mappings are usually one-to-one as in simple substitution, but can change within a

single message.These are the most general ciphers; they permit arbitrary substitutions for groups

of plain text characters. For illustrative purposes, we only discuss simple substitution ciphers

here.Suppose B is a plaint text n-character alphabet ordered us look as {b0,b1,…….bn-1}. A

simple substitution cipher then replaces each character of A by a corresponding character from

an ordered cipher alphabet C denoted by {f(b0),f(b1),f(b2),……….f(bn-1)}. Here the function

‘f’ represents a one-to-one mapping of each character of B to the corresponding character of C.

A plain text message N=n1n2n3 ……. is then written as Ek(n) = f(n1)f(n2) ……. Where mi is a

character of B. Typically C is simply a rearrangement of the characters in B.Product cipherA

product cipher involves a combination of transposition ( permutation) and substitution to

produce a cipher text. The products are of the form C1MC2N…….Cn where N is an un-keyed

mixing transformation or permutation and the C1 are simple cryptographic transformation. Thus

, a product cipher is the application of sequence of ‘n’ enciphering functions f1,f2,…….fn

where each f1 can be a permutation cipher P or a substitution cipher S . A1.2 illustrated the

application of the basic principle to a 12-bit message block .M= ( m1m2........m12) .we should

note that this example is for concept illustration purpose only , since in practice longer locks

should be used .The enciphering scheme alternately applies ‘k’ substitution Si and ‘k-1’

permutations Pi yielding C= Ek (M) =SkPkSk-1………..S2P1S1 (M) Where each Si is a

function of the key K. The 12-bit plaintext block is divided into four 3-bit sub-blocks each of

which is acted on by a different invertible 3-bit to 3-bit mapping or substitution cipher Sij. The

resulting 12 bits are scrambled by the permutation box Pi and input to the next round of

enciphering.The numeral of rounds for the cipher (Nn) varies with the block length and the key

length as shown in the below table.

The SubBytes Transformation

The SubBytes transformation is a non-linear byte substitution that acts on every byte of the

state in isolation to produce a new byte value using an S-box substitution table. The act of this

transformation is demonstrate in Figure 2 for a block size of 6.

This replacement, which is invertible, is build by composing two transformations:

1. Primarily the multiplicative inverse in the finite field explain prior (with element {00} mapped

to itself).

2. Second the affine transformation over GF(2) defined by:

For 0 £ i < 8 where bi is bit i of the byte and ci is bit i of a byte c with the value {63} or

{01100011}. Here and somewhere else a prime on a variable on the left of an equation specify

that its value is to be efficient with the value on the right.

In matrix form the latter component of the S-box transformation can be expressed as:

The final result of this two stage transformation is given in the following table.

The ShiftRows Transformation

The ShiftRows transformation operates individually on each of the last Three rows of the

state by cyclically shifting the bytes in the row such that:

Where the shift amount h(r, Nc) depends on row number r and block length as follows:

This By interchanging the rows lowest bytes wrap has the effect of moving bytes to the top most

priority bytes which the utilization is demonstrated in the lower positions in the row except that

the around into the top of the row where the needs are described below 6.

The MixColumns Transformation

The mixed column transformation is by changing elements in the matrix and treated as each and

every column as four-term polynomial. In the preceding matrix all the values are finite elements

as argued in

The mechanism of transformation is shown in the Figure 4 for a cipher block size of 6.

The Xor RoundKey Transformation

In the Xor RoundKey transformation Nc words from the key schedule (the round key described

later) are each added (XOR’ d) into the columns of the state so that:

where the round key words are added to the k rounds which then the range as to be from the o

with the value o is being utilized and is represented by the initial key round as shown in the

diagram and the primary key is to applied prior to the round function K round, c (shortened to k r

The byte that consists of each word as a key address that is shown aboveThe act of this alteration

is demonstrate in Figure 5 for a cipher block size of 6.

The Key Schedule

The output of the cipher key is the round key by taking the responsibility of the key schedule

with each and every round require a supplementary initial set with round essential nc word, build

which establish a whole sum of Nc (Nn + 1) words here nc represents number of cipher

rounds .And the key scheduled is deliberate as solitary dimensional array with I an index of

range k 0 £ i < Nc (Nn + 1) each or which individually comprises of a sub-array of Nc words.

The expansion of the input key into the key schedule proceeds according to the subsequent

pseudo code. The output of the cipher key is the round key by taking the responsibility of the

key schedule with each and every round require a supplementary initial set with round essential

nc word, build which establish a whole sum [b3,b2,b1,b0 ] to an output [b0,b3,b2,b1 ] . The

rounds which then the range as to be from the o with the value o is being utilized and is

represented by the initial

Remember the key which is described in the fig6 where nk=4 and nc=6 and can be produced

depending on the necessary utilizing a buffer of max(nc,nk)and this mechanism figured out in

6 and can also be diverse into some what easier, key schedules for Nk _ 6 and Nk > 6

respectively.

The Inverse Cipher

The above represented cipher code is a inverse cipher which is straight forward.

The Inverse ShiftRows Transformation

The InvShiftRows transformation mainly deals individually with the last three the state

cyclically altering the bytes the row in a way

where the cyclic shift values h(r, Nc) are given in Table 6.

The Inverse SubBytes Transformation

The needed for the inverse InvSubBytes transformation is given above. The below table is

called inverse S-box table which is required for transformations as above discussed.

The Inverse MixColumns Transformation

The InvMixColumns transformation acts independently on every This By interchanging the

rows lowest bytes wrap has the effect of moving bytes to the top most priority bytes which the

utilization is demonstrated in the lower positions in the row except that the around into the top of

the row discussed above.

The Equivalent Inverse Cipher

This type of cipher utilizes the identical type of keys for the forward cipher but the way of

execution is different though a continuous group of actions of transformations are to be are to be

transformed the inverse transform to convert into forward cipher this the reason that some of the

alterations and the type of execution is entirely different from others the order of sub bytes and

jumping of row transformations does not taken into consideration subBytes moves are changes

the value and the locations and in the same way the shift rows does the the thing that is exactly

opposite which is done by the subbyte subsequently XorRoundKey and InvMixColumns are

made to come into action to make the forward and inverse to be identical form to perform round

key addition column mixing the execution must be linear to the column input so that:

InvMixColumns(state xor h)=InvMixColumns(state) xor InvMixColumns(h)

where as h is the representation of a round key which is in the form of a state array. Therefore,

provide that an This type of cipher utilizes the identical type of keys for the forward cipher but

the way of execution is different though a continuous group of actions of transformations are to

be are to be transformed the inverse transform to convert since these do not operate in

association with the column-mixing step. The performance of the forward only have the structure

where it functions only round function to outcome in an proficient type of execution .By

transforming the inverse cipher into the identical sequence of operations as the cipher itself, it

can be carried out in the identical way, thereby achieving this efficiency.

CHAPTER-6

THE DES AND TRIPLE DES ALGORITHMS

6.1 DATA ENCRYPTION STANDARD

The most widely used encryption scheme is based on (DES) adapted in 1977 by the

National Bureau of Standards has tailored Data Encryption Standard which is most widely used

encryption in data encryption algorithm for 56-bit are utilized by 64 bit block and algoritham

converts 64 bit input into as 64 bit output, are utilized to reverse the encryption.

Before its adoption as a standard, the proposed DES was subjected to intense criticism, which

has not subsided to this day. Two areas drew the critics’ fire. First, the key length in IBM’s

original LUCIFER algorithm was 128 bits, but that of the proposed system was only 56 bits, an

enormous reduction in key size of 72 bits. Critics feared that this key length was too short to

withstand Brute Force attacks. The second area of concern was that the design criteria for the

internal structure of DES, the S-boxes, were classified. Thus users could not be sure that the

internal structure of DES was free of any hidden weak points that would enable NSA decipher

messages without benefit of the key.

6.1.2 DES ENCRYPTION

The overall scheme for DES encryption is illustrated in Figure below. As with any encryption

scheme, there are two inputs to the encryption function: the plain text to be encrypted and the

key. In this case, the plain text must be 64 bits in length and the key is 56 bits in length.

Fig 6.1.2(a) Encryption using DES

Looking at the left hand side of the figure, we can see the processing of the plain text

proceeds in three phases. First, the 64-bit plain text passes through an initial permutation (IP)

that rearranges the bits to produce the permuted input. This is go behind by a phase comprising

of 16 rounds of the identical function, which involve together permutation and exchange

functions. The output of the last (sixteen) round consists of 64 bits that are a function of the input

plain text and the key. The left and right bisect of the output are swop to fabricate the pre-

output. Finally, the pre-output is passed through a permutation (IP -1) that is the inverse of the

initial permutation function, to produce the 64-bit cipher text. Considering the exception of the

primary and final permutations, DES has the exact organization of Feistel cipher, as dipected in

the figure.

The right-hand portion of fig above shows the way in which the 56-bit key is used. At

first, the key is accepted through a permutation function. Then, for each of the 16 rounds, a sub

key (Ki) is produced by the combination of a left circular shift and a permutation. The

permutation function is the same for each round, but a different sub key is produced because of

the repeated iteration of the key bit.

6.1.2.1Initial Permutation:

The input to a table comprises of 64 bits A product cipher involves a combination of transposition

( permutation) and substitution to produce a cipher text. The products are of the form

B1MB2M…….Bn where M is an un- keyed mixing transformation or permutation and the B1 are

simple cryptographic transformation. Thus , a product cipher is the application of sequence of 'n'

enciphering functions f1,f2,…….fn where each f1 can be a permutation cipher P or a substitution

cipher S . A1.2 illustrated the application of the basic principle to a 12-bit message block . M=

( m1m2........m12) .we should note that this example is for concept illustration purpose only , since in

practice longer locks should be used .The enciphering scheme alternately applies 'k' substitution Si

and 'k-1' permutations Pi yielding C= Ek (M) =SkPkSk-1………..S2P1S1 (M) reversed, i.e. Li=Ri+1

(mod-2)f(Ki+1,Li+1) Ri=Li+1 When block ciphers are applied to data stream, the cipher mode defines

how the algorithm is applied block by block to the data stream.

Details of Single Round:

Fig 6.1.2 (b) Process involved in Single round

Figure: show the internal structure of a single round. . However, it is still important to select an

appropriately strong alternative from the number available in today's market place. The essential

objective is choosing a strong code, or a strong cryptosystem for that matter is to look at the work

factor it presents an attacker. The work factor is an estimate of how hard the attacker must work in

order to by pass the protection and achieves valuable goal. While it may, in some cases, increase

the attacker's work factor to keep as much secret as possible, keeping a crypto algorithm secret can

be a double-edged sword. If we don't know how the algorithm works- we can't tell if it has some

easy-to-exploit flaw. Good crypto algorithms rely exclusively on keys to protect the data. Revealing

the algorithms should not significantly improve an attackers like lihood of success.

To protect both equipment and information, network security must consider a wide range of

administrative, physical, and technical issues. To select an appropriate set of network security

measures, one first needs to evaluate the threat environment and assess the security techniques

can be selected and appliedmust be both physically secured and capable of isolation information

from each of various independent data streams the could pass through the node. In contrast to

this protection of individual links, end-to-end security uniformly protects each message along its

entire route from source to destination as is shown in A1.3 Thus messages pass through the

entire network of transmission links, local computers, intermediate nodes switches in an

encrypted form as provided by encryption device at the message originator. reserving the entire

message, reforming the message into a geometrical shape, rearranging the plain text by

scrambling a sequence of columns, and periodically permuting the characters of the plain text.

Let us now look at simple examples to illustrate this. 1. Message Reversal: In this method the

plain text is written backwards to produce a cipher textcan be rearranged in 5! = 120 different

ways. To enhance the security of the plain text message, we can thus choose one of these

rearrangements A drawback in using columnar transposition ciphers for computer applications is

that entire matrices of characters must be generated to encryption and decryption.

.1.2.2KEY GENERATION:

The subkeys are calculated using the Blowfish algorithm: Initially the q-array and the four p-

boxes in array with a fixed string and this string consists of hexadecimal digits of pi and next

xor q1 with 32 bits of key labeled C0 and D0.and kkep on continue for the process for each and

every bit of key and keep on repeating till the entire q-array has become xored with key bits.By

DES algorithm Encrypt the all-zero string, utilizing the 64-bit key. Replace the output of q1 and

q2 and encrypt this with the subkey. And carry this process till the q-array and all the four p-

boxes in array and the output varying constantly an at last there is a necessitate of 521

alterations for the outcome of all requisite keys and this perform this process number of times.A

48-bit that serves as input to the function F(R1-1,ki); every bit of key and keep on repeating till

the entire q-array has become xored with key bits.By DES algorithm Encrypt the all-zero

string, utilizing the 64-bit key. Replace the output of q1 and q2 and encrypt this with the subkey.

And carry this process till the q-array and all the four p-boxes in array and the output varying

constantly an at last there is a necessitate of 521 alterations for the outcome of all requisite keys

and this perform this process number of times.A 48-bit that serves as input to the function F(R1-

1,ki);

6.2 TRIPLE DATA ENCRYPTION ALGORITHM

Every TDEA operation is a compound technique of des encryption and the below operations are

utilized where let us Let CK (I) and VK(I) symbolize the DES encryption and decryption of I

utilizing DES key K correspondingly. Every TDEA encryption/decryption procedure (as

specified in ANSI X9.52) is a compound procedure of DES encryption and decryption operation.

The subsequent operations are utilized: In TDE A technique the alteration of 64 block I into a

64-bit block that defines as below O = CK3(VK2(CK1(I))) the same technique is followed by: O

= VK1(CK2(VK3(I))) specifies the following keying options for bundle as below.

The standard (h1, h2, h3)

Keying Option 1: independent keys are h1, h2 and h3 Keying Option 2: h3 = h1 where h1 and

h2 are autonomous keys and, Keying Option 3: h1 equal sh2 = h3.

A TDEA mode of operation is backward compatible with its single DES counterpart if, with

compatible keying options for TDEA operation,

1. An encrypted plaintext work out utilizing a single DES mode of operation can be decrypted

appropriately by a corresponding TDEA mode of operation; The best proficient method 65to

break TDEA is through thorough search of the key space. Even though a number of excellent

algorithms have been urbanized TDEA is utilized regularly for the reason that: It has been

frequently tested and found to be much protected. Use by criminals with malicious intent ●

Encryption keys can become lost rendering the associated data unrecoverable .Encryption that is

managed by the user can cause problems in a managed network by rendering necessary files

inaccessible to the network managers .In this document we talk about TDA simple substitution

cipher then replaces each character of A by a corresponding character from an ordered cipher

alphabet C denoted by {f(b0),f(b1),f(b2),……….f(bn-1)}. Here the function ‘f’ represents a one-

to-one mapping of each character of B to the corresponding character of C. A plain text message

N=n1n2n3 ……. is then written as Ek(n) = f(n1)f(n2) ……. Where mi is a character of B.

Typically C is simply a rearrangement of the characters in B.Product cipherA product cipher

involves a combination of transposition ( permutation) and substitution to produce a cipher

text. The products are of the form C1MC2N…….Cn where N is an un-keyed mixing

transformation or permutation and the C1 are simple cryptographic transformation. Thus , a

product cipher is the application of sequence of ‘n’ enciphering functions f1,f2,…….fn where

each f1 can be a permutation cipher P or a substitution cipher S . A1.2 illustrated the application

of the basic principle to a 12-bit message block .M= ( m1m2........m12) .we should note that this

example is for concept illustration purpose only , since in practice longer locks should be

used .The enciphering scheme alternately applies ‘k’ substitution Si and ‘k-1’ permutations Pi

yielding C= Ek (M) =SkPkSk-1………..S2P1S1 (M) Where each Si is a function of the key K.

The 12-bit plaintext block is divided into four 3-bit sub-blocks each of which is acted on by a

different invertible 3-bit to 3-bit mapping or substitution cipher Sij.action can be decrypted

accurately by a consequent single DES mode of operation. When utilizing Keying Option 3 (K1

= K2 = K3), TECB, TCBC, TCFB and TOFB modes are backward attuned with single DES

modes of process ECB, CBC, CFB, OFB correspondingly.

I DE O

Fig 6.2 (a) TDEA encryption and decryption process

DES Ek1 DES Dk2 DES Ek3

DES Dk1 DES Ek2 DES Dk3I O

CHAPTER-7

THE BLOWFIHS ALGORITHM

Blow fish is the fastest block cipher in the rife use,devoid of altering of keys.Each and every

new key has to pre –process identical to encrypt four kilobytes of text and is really slothful

estimate to other block ciphers.This keep away this its utilization in secure applications ,and this

is not a trouble in others. In one application, it is an advantage: the password-hashing technique

utilized in Open BSD utilized an algorithm derivative from Blowfish that carries utilization of

the unhurried key schedule;the motive is the supplementary computational effort obligatory

gives fortification footprint of merely over 4 kilobytes of RAM. This system is a not a mess yet

for older desktop and laptop computers, even though it does avert utilization in the minimum

embedded systems like early on smartcards. Blowfish is does not patent and is accordingly

generously reachable for someone to utilize. This recompense has throws in to its fame in

cryptographic software.

7.1 BLOWFISH ALGORITHM

It successfully utilized for encryption because it is a symmetric block cipher and it mainly

comprises of variable key length from 32 bit to 448 bits,and intention is to make data safe. It is

introduced in 1993 by Bruce Schneier as a free option to presented encryption algorithms.The

main advantage of blow fish is it is freeware which is and license-free, and is accessible free for

each and every one.Blowfish is simple iterating encryption function sixteen times.the range size

of the block is 64 bits,448 bits.It is more suitable for applications at where the key does not

change frequently and it has a very difficult initialization phase essential for any encryption can

occur, the real encryption of data is very capable on huge microprocessors.Variable-length key

block cipher is Blowfish.It is faster than any other algoritham with implementation on 32-bit

microprocessor with large data caches.

7.1.1 Feistel Networks

A Feistel network is a general method of transforming any function (usually called an Ffunction)

into a permutation is the normal method of feistal networks.It It is invented by Horst Feistel and

as well as utilized in several block cipher designs. The functioning of a Feistal Network is given

as Split each block into halves and next is Right half becomes new left halve and next is New

right half is the concluding result when the left half is XOR’d with the result of applying f to the

right half and the key.keep in mind preceding rounds can be consequent even if the function f is

not invertible.

Fig 7.1.1 (a) Fiestel network

7.1.2 The Blowfish Algorithm:

Li-1 K

f+

Li Ri

Ri-1

It successfully utilized for encryption because it is a symmetric block cipher and it mainly

comprises of variable key length from 32 bit to 448 bits and intention is to make data

safe. It is introduced in 1993 by Bruce Schneider as a free option to presented encryption

algorithms. The main advantage of blow fish is it is freeware which is and license-free,

and is accessible free for each and every one. Blowfish is simple iterating encryption

function sixteen times the range size of the block is 64 bits,448 bits. It is more suitable

for applications at where the key does not change frequently and it has a very difficult

initialization phase essential for any encryption can occur, the real encryption of data is

very capable on huge microprocessors. Variable-length key block cipher is Blowfish. It is

faster than any other algorithm with implementation on 32-bit microprocessor with large

data caches. A simple substitution cipher then replaces each character of A by a

corresponding character from an ordered cipher alphabet C denoted by {f(b0),f(b1),f(b2),

……….f(bn-1)}. Here the function ‘f’ represents a one-to-one mapping of each character

of B to the corresponding character of C. A plain text message N=n1n2n3 ……. is then

written as Ek(n) = f(n1)f(n2) ……. Where mi is a character of B. Typically C is simply a

rearrangement of the characters in Byproduct cipherA product cipher involves a

combination of transposition (permutation) and substitution to produce a cipher text. The

products are of the form C1MC2N…….Cn where N is an un-keyed mixing

transformation or permutation and the C1 are simple cryptographic transformation. Thus ,

a product cipher is the application of sequence of ‘n’ enciphering functions f1,f2,

…….fn where each f1 can be a permutation cipher P or a substitution cipher S . A1.2

illustrated the application of the basic principle to a 12-bit message block . M=

( m1m2........m12) .we should note that this example is for concept illustration purpose

only , since in practice longer locks should be used

7.2 DESCRIPTION OF THE ALGORITHM

Blowfish is a variable-length key, 64-bit block cipher.A key-expansion part and a data-

encryption part are the two parts that the algoritahm comprises. Key expansion change a key of

at most 448 bits into numerous sub key arrays totaling 4168 bytes. Data encryption carries

through 16-round Feistel network. Every round comprises of a key reliant permutation, and a

key- and data-dependent changeover. All process are XORs and additions on 32-bit words. The

only additional operations are four indexed array data lookups per round.

7.2.1.Subkeys

It utilizes a large number of subkeys. The keys must be processed earlier to any data encryption

or decryption. The q –array comprises of 18 32 –bit subkeys:q1,q2,q3……………q18.

2. There are four 32-bit p-boxes with 256 entries each:p1,0, p1,1,..., p1,255;p2,0, p2,1,..,, p2,255;

p3,0, p3,1,..., p3,255;p4,0, p4,1,..,, p4,255.

Encryption

It consists of 16 rounds where the input is of 64-bit data elements ie x and divided into

two halve of 32-bit xl,xr.for i = 1 to 16: xL = xL XOR Pi xR = F(xL) XOR xR interchange Swap

xl and xr.After the completion of the sixteenth round, interchange xl and ar again for previous

swap. Then, xR = xR XOR P17 and xL = xL XOR P18. Lastely again by combining x1 and xr

achieve the ciphertext. Decryption is accurately identical as encryption, apart from that P1, P2,...,

P18 are utilized in the undo order .To revel the loop and make certain or to arrange the all sub

keys in order it require greatest speed and make certain that all sub keys are stored in cache.

7.2.3 Generating the Subkeys

The subkeys are calculated using the Blowfish algorithm: Initially the q-array and the four p-

boxes in array with a fixed string and this string consists of hexadecimal digits of pi and next

xor q1 with 32 bits of key.and kkep on continue for the process for each and every bit of key and

keep on repeating till the entire q-array has become xored with key bits.By Blowfish algorithm

Encrypt the all-zero string, utilizing the subkeys. Replace the output of q1 and q2 and encrypt

this with the subkey. And carry this process till the q-array and all the four p-boxes in array and

the output varying constantly an at last there is a necessitate of 521 alterations for the outcome

of all requisite keys and this perform this process number of times.

7.2.4 DESIGN DECISIONS

A 64-bit block size yields a 32-bit word size, and .To maintains block-size compatibility with

existing algorithms a 32-bit word size is yield by 64-bit block size and it can scale up to128-block as well as down to slighter

The starting process are selected as are many options like as XOR, ADD, and MOV from

a cache are proficient on architectures that are provided by several companies and all the

sub keys.

To safeguard the complete entropy subkey generation is intended as well as it is planned

to share out set of allowed sub keys erratically all through the domain of achievable sub

keys. The letter pi is take for two reasons for the random sequence that are not linked to

the algorithm and the next is to store the piece of algorithm.

During sub key producing each key of sub key alter with each pair of sub keys produced

and this is to guard the the attacks on the sub key and it reduces the storage necessitate.

The subkey is dependent on each bit of the key and the limit of the key is certainThe

448 limit on the key size make certain that the each bit of each sub key depends on every

bit of the key. Split each block into halves and next is Right half becomes new left halve

and next is New right half is the concluding result when the left half is XOR’d with the

result of applying f to the right half and the key keep in mind preceding rounds can be

consequent even if the function f is not invertible manufacture process is fixed.

Generally in sub key generation highly linked key bits like an alphanumeric ASCII

string with the bit of each byte to 0 that will create random subkeys

It is the most time taking process for generating sub keys and difficult for brute-force and

the sub key are very long to be store on tape,

The mainly able way to break blowfish is through thorough hunt of the keyspace.

Evolution of project:Most of the resources utilized were taken from online research sites like sciencedirect.com, techrepublic.com, findwhitepapers.com and ACM.com. The obtainable system comprises of files

with literally no file security standards like encryption techniques are to be put into practice due to the factors such as Reading or tapping data, Manipulating and modifying data, Unlawful use of files, Corrosion of data files, Distortion of data transmission, Disturbance of the operation of equipment or systems, adjacent to which numerous security actions had to be taken up, The core concern of (1) is secrecy and confidentiality. Confidentiality has always played an vital role I diplomatic and military matters. Often Information ought to stored or transferred from one place to another devoid of being exposed to an rival or enemy. Key management is also associated to confidentiality. This deals with generating, distributing and storing keys.Items (2-4) are mainly concerned with reliability. Often the expression integrity is utilized as a gauge of genuineness of data. Also Computer files and networks must be secluded against intruders and Unauthorized. Items (5-6) are a diverse aspect of the security of the information, its continuity

Developing Process

The appraisal criteria were divided into three main categories: 1) Security, 2) Cost, and3) Algorithm and execution Characteristics. Defense was the mainly vital factor in the appraisal and encompasses features like conflict of the algorithm to cryptanalysis, soundness of its mathematical basis, randomness of the algorithm output, and relation refuge as compare to other candidates. Next cost was a second vital area of evaluation that encompassed licensing necessities, computational speed on different platforms, and memory necessities. As one of NIST’s aim was that the final AES algorithm be accessible worldwide on a royalty-free basis, public comments were particularly hunted on intellectual assets claims and any potential conflict. The tempo of the algorithm on a range of platforms required to be measured. All through Round 1, the spotlight was mainly on the speed related with 128-bit keys. During Round 2, hardware implementations and the speeds associated with the 192 and 256-bit key sizes were addressed. Memory necessities and software execution constraints for software implementations of the candidates were also vital considerations. The third area of evaluation was algorithm and execution characteristics like as flexibility, hardware and software suitability, and algorithm ease. Flexibility comprises the ability of an algorithm:To handle key and block sizes away from the minimum that must be supported,To be apply steadily and efficiently in many diverse types ofenvironments, andTo be implement as a stream cipher, hashing algorithm, and to facilitate additional cryptographic services. It must be realistic to execute an algorithm in equally hardware and software, and efficient firmware implementations were measured helpful. The virtual minimalism of an algorithm’s intends was also an appraisal factor. During Rounds 1 and 2, it become evident that the a variety of issues being analyzed and discuss often cross into extra than one of the three main criteria headings.

STRENGTHS

Encryption is the most effective way to achieve data security

Encrypting a file makes its contents unrecognizable to applications and to anyone

snooping around on your home or office computer

Confidentiality: Only genuine destination can access data.

Integrity: Data cannot be changed in the transmission process.

For financial transactions and payment processing industries.

WEAKNESS

Encryption takes computer processor time. The more complex the encryption the more

processing it will take

Use by criminals with malicious intent

Encryption keys can become lost rendering the associated data unrecoverable.

Encryption that is managed by the user can cause problems in a managed network by

rendering necessary files inaccessible to the network managers

CONCLUSION

In this document we talk about Blowfish, it is a variable-length key block cipher. It is only

appropriate for applications where the key has not change often, like a communications link or

an automatic file encryptor. It is appreciably earlier than DES when execute on 32-bit

microprocessors with huge data caches, like as the Pentium and the PowerPC. Even though there

is a compound initialization phase requisite before any encryption can take place, the actual

encryption of data is very resourceful on large microprocessors. Linux comprises Blowfish in the

mainline kernel, starting with v2.5.47. Blowfish is a 16 pass block encryption algorithm that has

never been broken. The best proficient method to break Blowfish is through thorough search of

the key space. Even though a number of excellent algorithms have been urbanized BLOWFISH

is utilized regularly for the reason that: It has been frequently tested and found to be much

protected. It is tremendously rapid due to its taking benefits of built-in instructions on the present

microprocessors for basic bit shuffling operations. The recital indices here are the security and

pace of the algorithm. This study is applied to diverse types of data; text, sound and image. For

each and every case the encryption/decryption key length has been altered and its outcome on the

performance was discerned. Furthermore, the file volume is altered and its affect on the recital of

the algorithm was noticed. This has revealed that changing the key length has no outcome on the

encryption or decryption time where altering the plaintext file size is straightly reflected on the

processing time. The results obtain here have been transformed into modules of equations of

high orders thus the future performance of the algorithm may be predict from these equations

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