Interruption Interception Modification And Fabrication Attacks Computer Science Essay

The communication has been playing an important role since the dawn of civilization. It has become a fundamental element of existence in the societies that happen to be highly networked where we live in. Some types of communication types have been developed during the earlier stage of civilization which led to evolving various kinds of communications till today. The communication through the internet is the greatest types of the latest communication types. There are different types of communications prevailing inside our day to day life such as Radio communication, Mobile communication, Telephonic communication and Network communication. Each communication type has its importance but the communication over the network has been mostly implemented in our life and has been evolved as the utmost powerful and highly developed communication methods. The network communication method has created a great effect on lives of humans. So as this method is slowly but surely developing and being employed by a lot of people and organizations, such advance in the technology has resulted in the security issues such as threats or malicious attacks to the individuals and organizations. So there's a need to come across these threats and attacks which resulted in the introduction and development of different mechanisms for providing different services and CRYPTOGRAPHY is one of the mechanisms which is mostly found in the network communication.


There are different types of security attacks which affect the communication process in the network and they are as follows

Interruption: This type of attack is because of the obstruction of any kind through the communication process between one or more systems. So the systems which are used become unusable following this attack by the unauthorized users which results in the wastage of systems.

Interception: The phenomenon of confidentiality plays an important role in this type of attack. The info or message which is sent by the sender is intercepted by an unauthorized individual where in fact the message will be changed to the different form or it'll be used by the average person for his malicious process. Therefore the confidentiality of the message is lost in this type of attack.

Modification: As the name indicates the message which is sent by the sender is modified and sent to the destination by an unauthorized user. The integrity of the message is lost by this type of attack. The receiver cannot receive the exact message which is sent by the source which results in the poor performance of the network.

Fabrication: In this kind of attack a fake message is inserted into the network by an unauthorized user as if it is just a valid user. This results the loss of confidentiality, authenticity and integrity of the message.


DEFINITION: The term cryptography is the science of securing information by different techniques such as encryption and decryption. The word cryptography comes from the Greek word Kryptos this means hidden and graphia means writing, so totally it means hidden writing. Cryptology and Cryptanalysis are closely related to Cryptography. Cryptanalysis is the procedure of breaking the ciphers and coded without by using a key and whereas the cryptology is the mixture of both cryptanalysis and cryptography. In the process of cryptography the data which is usually to be transmitted and received is enciphered by different keys so that it can't be understand by the unauthorized users. But only the sender and receiver can be able to understand why data.

HISTORY: The idea of cryptography was originated in 2000 B. C. in Egypt where the Egyptians practiced hieroglyphics where it can be used to reveal the story of the dead people by decorating their tombs and this process was practiced in order to make them to see more ceremonial, majestic and noble however, not to cover the message themselves. But later many encryption techniques have evolved for show into practical applications to be able to hide the information from others. The annals of cryptography was very interesting and many changes have been undergone through many centuries. Through the ages of civilization the important issue was the maintenance of secrecy due to the different reasons by individuals or groups and this secrecy maintenance helps the individuals or groups to get a competitive edge, the real intentions of each individual can be hidden and also the weakness can be reduced. The innovations or advance in the technology has led to the changes in cryptographic history. The process of cryptography has begun by sculpturing the message on wood or stone and then it is delivered to the individual who should be received and it is deciphered to the original text by different process. However the development of cryptography has undergone many changes from carving the message on wood to the blast of binary codes. These streams of binary codes are transmitted over network wires, airwaves etc before however now these binary codes are submitted the proper execution of 0's and 1's through internet cables or open airwaves. These packets are encrypted so that they aren't disturbed by the unauthorized users. The Egyptians have started the procedure of cryptography by replacing the original message with different message with the aid of cipher which process is recognized as substitution cipher where each letter in the message to be sent is replaces with different letter so that unauthorized cannot understand. This message is again retransformed to the initial form by the receiver. For example the sentence or message


is changed to

TUBGGPSETIKSF VOJWFSTJUZ (Encrypted text or cipher text) where each letter is replaces with the preceding letter so that no one can understand.


During the ancient times there have been different cryptographic methods which were implemented for securing the info safely such that it can't be accessed by an unauthorized user. So different methods are as follows

Hebrew cryptographic method: That is one of the ancient methods of cryptography where flipping of the alphabets occurs so that the mapping of the each letter in the original alphabet and the flipped alphabet should not match each other which means the corresponding letter in the original alphabet should vary in the flipped alphabet which approach to encryption is recognized as atbash.



For example the encrypted form of the term "Staffordshire University" is "hgzuuliwhsriv fmrevihrgb".

Spartans method: This technique of cryptography was implemented around 400 B. C. by the Spartans where they used to encrypt the message or information by by using a sheet of papyrus and a wooden stick or rod. The message which is usually to be sent is written on the papyrus and it is wounded throughout the stick or rod which information can be known by the receiver only when the message was wounded around the right staff so that the letters would properly match. This process is known as scytale cipher and when the paper is taken off the stick or rod the message which was written on the paper was just found as the band of the random characters which different pieces papyrus are delivered to group of soldiers by Greek government with the help of carriers. After getting the papyrus the soldiers then wound this papyrus round the stick or rod which is of equal diameter and length so the letters which can be random match with the letters with the second rod and the message which is sent can be known. The soldiers use this method for the info about the strategic moves and military directives.

Julius Caesar method: That is also one of the ancient methods of cryptography where Caesar developed a method where the letters of the word are shifted by some number which is defined. He developed this technique because of his non trustiness on his messengers. So he used to shift the letters by the quantity 3 such as the letter A is replaced by letter D. So the one who knows the "shift by 3 rule" can only just decipher the message.

STUDENT (Plain message)

VWXGHQW (encrypted message)

CONCEPT: The primary concept of cryptography is the process of securing the info by changing the initial form of the text or message to the proper execution which cannot be read by the unauthorized user. The message which is sent actually by the sender is known as plaintext which can be read by everyone and the encryption technique is put on this plain text which results in the formation of cipher text or encrypted text which cannot be read by an unauthorized user. An encryption algorithm is used to convert the plain text into cipher text and again this cipher text is retransformed into plain text by decryption algorithm. This means that cryptography is the science which is used for protecting the message or information by providing various ways and process to be able to convert the message or information which can't be read by anyone. The data or message is converted in such a way that the

No access of data for an unauthorized person

Information within the info frames is hidden

Data authentication is formed

The altering of the info is avoided

The message originator cannot disown the data

So the info which is transmitted on information and communication systems can be protected or secured by the technology known as cryptography. This technology is applied in many fields such as finance, personal data, military etc. This technology offers a method of authentication verification of the data so that the real culprit can be caught who interrupts the confidentiality and integrity of the data.


Cryptography: The science of protecting the message or data by using different techniques is recognized as cryptography.

Cryptosystem: The procedure of encryption and decryption comes under cryptosystem.

Cryptanalysis: The procedure of converting the plaintext from the ciphertext without use of an integral.

Cryptology: It is the combined study of cryptography and cryptanalysis.

Encipher: The act of converting the info which is can't be readable by an unauthorized user.

Decipher: The act of converting the data into readable format.

Plain text: This is the original message or the initial message which is sent by the sender to the recipient. This also called clear text or original text.

Encryption: This is the process of converting the plaintext or original text into the text to be able to pay the message which can't be understood by any unauthorized users.

Ciphertext: The written text which is sent for encryption results in the form of text known as cipher text or encrypted text which can't be read by unauthorized users.

Decryption: This is the opposite of encryption where in fact the encrypted text or cipher text is retained to its original form employing this technique. The conversion of cipher text to plain text occurs in this technique.

Hash algorithm: This is the algorithm which can be used in the encryption technique for the conversion of large string to the fixed length string. This increases the speed of the process.

Key: Key is the specified value which is employed for encrypting the plaintext to produce the ciphertext. The worthiness of the main element will be high. It's the series of bits and instructions which governs encryption and decryption

Cipher: This is the algorithm which is employed for the translation of the plaintext to the ciphertext which is the intermediate form


The main objective of the cryptography is to secure the info which is sent from the sender to the receiver so that it cannot be accessed by any unauthorized user and to be able to maintain the security of this information cryptography has need to manage some characteristics that are as follows

Confidentiality: The phenomenon of confidentiality plays an important role in cryptography. Confidentiality is the technique of securing the information or message such that it can only just be accessed only by a certified user who is proposed to read it. The confidentiality of the info loses its importance when it could be accessed by an unauthorized user. So when a message is sent from A to B, only B should be able to understand the message.

Authentication: The phenomenon of authentication also plays a significant role in cryptography. The identity of the sender who's sending the message is very important for the receiver. Which means this is the process of sending the identity proof the sender to the receiver in a way that the receiver can have the ability to know the individual who is sending the message. The primary concept this is actually the assurance.

Integrity: The integrity of the message has quite definitely importance in cryptography. The message which is sent by the sender ought to be the same when it is received by the receiver. The message should not be altered or changed through the transmission process by any unauthorized users. So this is the technique of making sure the message which is sent is not altered or tampered through the transit. The contents which are present at the sender should reach the receiver with the same contents with no change.

Non-repudiation: This is the method to make certain that the message which is sent is nor disowned. The s ender after sending the message should not declare it has not sent the message. After the message is sent by the sender then he's the originator of the info. He has no authority of denying of sending the data.

So they are the characteristics of cryptography where all these elements are maintained and implemented during the process of transmission of data from sender to the receiver.


A key plays an importance role in the classification of the cryptographic techniques. The number of keys used decides the sort of cryptographic techniques used. So the two important cryptographic techniques area s follows

SINGLE OR SECRET KEY CRYPTOGRAPHY OR SYMMETRIC ENCRYPTION: The single key cryptography is one of the key cryptographic techniques where only an individual key is utilized for encryption and decryption of the data or message. So only an individual key is accountable for the process of encryption and decryption. That is also known as symmetric key or secret key or private key encryption. Therefore the procedure for encrypting and decrypting the message or information or data with the help of a single key is recognized as single key cryptography. The exact same key which is employed for encryption is also used for decryption. The important point of this kind of cryptography would be that the both transmitter and the receiver should accept on a single key.

Symmetric cryptography or encryption between A and B:

The process of single cryptography takes place between A and B by sending the message between them. The message which is usually to be sent by the should not be accessed by an unauthorized user and it should be in a position to read by only B. To be able to be sure that only B has to browse the message a secret key is generated by A. Therefore the secret key which is produced is used for the encryption of the message and this encrypted message is delivered to B by means of ciphertext. This technique is recognized as encryption. Inorder to learn the encrypted message by B there's a need of the trick key which is made by A. So the secret key is transmitted by the to B by different means. The key can be delivered to B directly in person by way of a but it depends on the distance between A and B which effects time. If the distance is more it requires additional time and vice versa. The availability of B also plays an important role in sending the main element. So as soon as the main element is received by B then your decryption of the data occurs with the same type in order to retain its original form which is the plain text. So the secure transmission of data occurs between A and B.


The main problem in symmetric cryptography is with the key which are being used to encrypt and decrypt the data or message. The key which is utilized here is no more secure. Inorder to transfer the message in the symmetric cryptography the sender should send the key combined with the message through internet in the form of e-mail or through IRC services. So this type of transmission of keys is more insecure so that the data can be altered or tampered. The key can be transmitted physically however the distance between your sender and the receiver plays an important role and which is insecure. The procedure of transferring the main element verbally via a phone line results the leakage of the conversation to others. The sharing of the keys is also one of the issues in this kind of cryptography. The other problems in this kind of cryptography are key distribution and key management. This type of cryptography lacks in providing data integrity, non-repudiation and data authentication. Digital signatures can't be created by symmetric cryptography.


The public key cryptography is also one of the primary cryptographic techniques which is used for the secure transmission of data. Predicated on the security issues which are limited in secret key cryptography the public key cryptography has been evolved. This concept was introduced by Whitfield Diffie and Martin Hellman in 1975. The process where the encryption and decryption of the info or message occurs by two keys rather than an individual key is the general public key cryptography and this technique is known as asymmetric key encryption. As the name indicates asymmetric key encryption, one key is utilized for encrypting the info and the other key is utilized for decrypting the info. These two keys form a pair of keys and the blend of these two keys is known as key pair. Both keys which are used here are public key and secret key or private key. The general public key can be liberally distributed to anybody which is used for encryption and therefore this is named as public key encryption. The other key which is the private key or secret key cannot be distributable to anybody and can be used for decryption. The secret key is private to any communicating part taking part in the process. In this kind of cryptography the message or data can be encrypted with only one key and decrypted with the other key where in fact the key which is utilized for the encryption cannot be used for decryption. Therefore the data or message which is encrypted by the public key should only be decrypted by the private key and vice versa which means the info which is encrypted by the private key should only be decrypted by the public key which results in asymmetric cryptography.

Asymmetric cryptography or encryption between A and B:

The asymmetric key encryption occurs between A and B by sending message or data between them. The message which is usually to be delivered to b should not be accessed by any unauthorized user. So the decryption of the message should take place with the aid of the private key by B. So B contains both private key and the general public key. The general public key which is distributable is distributed to some and a encrypts the message or data by using the general public key which is sent by B. Therefore the file which is encrypted by A is sent to B where in fact the decryption of file takes place by making use of the private key. So the message or data cannot be accessed by any one because the private key is utilized for decryption which results in the secure transmission of data. SO the security of the info is more in the public key or asymmetric cryptography or encryption.

The above process reveals that the sole the general public key is utilized for encryption and only the private key can be used for the decryption of the data which reduces the unwanted access of data by an unauthorized users. The loss of data will be suprisingly low in this kind of cryptography. The possibility of tampering or alteration of the data or message is very low in this type of encryption. The exchange of information or message is very secure in this technique. As with the symmetric encryption the sharing of key is not essential for the encryption or decryption since it uses different keys for different process. The general public key is in charge of all the communications however the private key remains silent with no sharing. So each recipient has its key which is exclusive and this key can be used to decrypt the data which is encrypted by its opposite part.


The major problem in this kind of encryption is key lengths. The lengths of the keys which are being used in public key encryption are incredibly large of 1024 bits to 4094 bits. This leads to the low speed of transmission of the info. The main element lengths in symmetric cryptography are less from 40 bits to 256 bits which assists with the fast transmission of the info when compared to public key cryptography. So when compared to symmetric key cryptography the general public key cryptography is most secure. The messages can be easily transmitted and can be secured in public areas key cryptography. The key distribution in the public key cryptography is the primary asset because of this type of encryption. The key management problem can be avoided in this encryption. the strong cryptography can be provided by the general public key encryption which is the revolution in the technology. So public key cryptography has more benefits than private key encryption.


The algorithm is the step to step procedure or the group of mathematical rules which are being used for enciphering and deciphering the message or information or data. There are lots of algorithms which are being used in the cryptography and they are recognized to everyone. So the different types of encryption algorithms are as follows


As the name indicates that in this type of encryption only an individual key or a dedicated key is utilized for both encryption and decryption. The trick key algorithms which are being used widely are as follows

Data Encryption Standard (DES):

Data Encryption algorithm is one of the trick key encryption algorithms which is the most widely used. The Data Encryption Standard specifies a FIPS approved cryptographic algorithms as required by FIPS140-1. THE INFO Encryption Standard (DES) algorithm has been produced by IBM in the entire year 1970s and the adaptation was created by National Institute of Standards and Technology (NIST). That is also specified in the ANSI X3. 92 and X3. 106 standards and also in the Federal FIPS 46 and 81 standards. The exportation of the algorithm is strictly restricted by the government so that it could be employed by the unauthorized people or government.

Data Encryption Standard (DES) algorithm provides basic foundation for the info protection. The DES is a block cipher which is of 64-bit block size which converts the 64-bit input in to the 64-bit output through the use of the 56-bit key to each 64-bit data. There are 72 quadrillion or even more keys which are being used for encryption. So for every message or the info a suitable key is selected from these possible keys and then your process of encryption and decryption takes place with the same key which is the private key or secret key. But due to the innovation in the technology this kind of algorithm has proved insecure which led to the introduction of Triple-DES (3DES) ALGORITHM where in fact the name itself indicates that the encryption is performed 3 x which is more secure and runs on the different key for every encryption.

Controversies around DES:

The Data Encryption Standard (DES) has been bounded by different controversies such as the key length which s used is utilized in this type of algorithm has been reduced from 128 bits to 64 bits which led to the compromise on security and the other one is the exportation of the algorithm to numerous countries.


The Data Encryption Standard (DES) Algorithm has many applications apart from encryption and authentication of data. So the several applications are as follows

Data Storage and Mail Systems: The info which is stored in the computers can be protected by the procedure of encryption and authentication. The passwords which are created by the users in the computers are encrypted by the systems and are stored in the computer memory. An individual when enters the password again for signing then your encryption of this password also occurs which is weighed against the other encrypted password and the access to the computer takes place when they both match otherwise the access is denied. The encryption of the password is done by Data Encryption Standard (DES) algorithm with the key which is equal to the password and the plaintext which is equal to the user's identity.

The files which are present in the computer can even be encrypted by Data Encryption Standard (DES) algorithm for the storage. The computers have a key notarization system that happen to be built-into them and are being used to secure the files from unauthorized access, modifications etc. This Key notarization also helps in providing digital signature capability by using DES. DES gives the users the ability of exercising several commands for the intended purpose of key management, data encryption and authentication functions. The facilities execute notarization which on encryption seals a key or a password. The sealing of key or password occurs with the transmitter and receiver identities. Therefore the receiver must definitely provide the correct identity of the transmitter in order to decrypt the message. This technique of notarization is applied in ANSI standardX9. 17 in order to protect against key substitutions which may lead to the compromise of the sensitive data. The secure mail can even be provided by DES. The conjunction of the mail system and the main element notarization system helps in providing the secure mail. The header which contains the information which is essential to decrypt and authenticate the mail file is appended automatically to the file which is transmitted to the receiver. Therefore the decryption and authentication of the file occurs by the receiver in a near transparent manner.

`Electronic Funds Transfer (Wholesale and Retail): This is one of the main applications of the Data Encryption Standard (DES) algorithm. The DES plays an important role in protecting the wholesale and retail electronic funds transfer messages. Different standards such as ANSI X9. 9 and ANSI X9. 19 have been developed Electronic Funds Transfer (EFT) messages. The efforts made by these communities have led to the formation of encryption standards (ANSI X9. 23 Draft) and Key management (ANSI X9. 17 & ANSI X9. 24 Draft) standards. The DES is applied in workstations, point of sale terminals, automated teller machines and host computers. The range of data which is protected by DES is of the number from 50$ to a multi-million-dollar transfer. The primary criterion which helps the DES algorithm of its use in the wide selection of EFT applications is the Flexibility. The standards that happen to be developed for EFT application are being developed globally and so the procedure for encryption, authentication and key management have grown to be global. The daily transfer of vast amounts of dollars is performed by the US government and the security of the transfer is taken by the Department of Treasury by initiating its policy on the authentication of EFT messages. The support of the Federal Reserve Bank is given to the Treasury in order to make the policy successful. The system which the treasury is considering uses hand-held tokens which contains DES key that are generated for the purpose of a particular individual. The authentication of the EFT message which contains the individual's identity is performed by the key which is supplied by the token. The message which is authenticated is the electronic substitute for a signed paper document.

Electronic Business Data Interchange: The very big companies have large part of the business transactions and these transactions should be programmed so that cost can be reduced and increases efficiency. So in order to achieve each one of these large companies are developing the procedure of automating business. The original approach to business transactions which is paper based is replaced with the electronic means of transmission. The ANSI Accredited Standards Committee X12 is accountable for these communications by developing different formats. The transaction between your seller and buyer can be accessed by any unauthorized users. So there is a dependence on protecting the info from the modification and eavesdropping which is performed by the procedure of cryptography or encryption technique. This system is very effective in protecting the info from unwanted users. The info which is sent by the sender cannot be readable by anyone unless the receiver. Many DES standards have been developed for the purpose of the Electronic business data interchange. The standard ANSI X9. 9 helps in protecting the data from the unnecessary modifications by the unauthorized user, the unauthorized disclosure can be avoided by the draft ANSI Standard X9. 23. The techniques of ANSI Standard X9. 17 used for the secure generation, distribution and the storage of DES keys. These explained methods are implemented by General Motors and seven associated banks to be able to protect their business transactions.


In addition to these different applications of DES it has some weaknesses which are as follows

Brute Force Attack: The brute force attack is the simplest attack to decipher. The attack of brute force on the DES is due to the length of the key which is relatively small that is 56 bit and also computational power of the computers which is increasing daily. Inside the 19th century this type of attacks are not done by the hackers because the expense of the computers are relatively high and the hackers couldn't afford to buy it. But the innovation in neuro-scientific computing and technology made the hackers to easily buy the computers and try to hack. Now a days every computer is utilized for hacking. The powerful, Faster and cheaper techniques which are being used by the hackers are Field Programmable Gate Array (FPGA) and Application -Specific Integrated Circuits (ASIC). Enough time taken up to break the cipher is directly proportional to the main element length in the brute force attack. In this kind of attack the random generation of the keys occurs and these keys are applied on the ciphertext till the initial key is generated. Therefore the fake key decrypts the message directly into its original form. So the key factor which is usually to be considered this is actually the key length. The longer the key length the higher is the security. In a n bit long key 2 to the power of n steps must break the cipher. In order long as the main element length will increase then the secure data transmission takes place in the network communication. So in order to obtain the safe encryption the key lengthy should be long such as the 128 bits which results in the reliable means of encrypting the message.

Differential Cryptanalysis Attack: This sort of attack is available near to the pairs of ciphertexts where the plaintext has some particular variations and these variations are analysed by this attack when the plaintext is propagating through several DES rounds when they are encrypted by using the same key.

TRIPLE DATA ENCRYPTION STANDARD (3DES): Triple Data Encryption Standard (3DES) is also one of the encryption algorithms which is the minor variation of Data Encryption Standard (DES). Triple-DES is adopted by ANSI as the X9. 52 standard and also been proposed as a revision of FIPS 46, known as draft FIPS 46-3. This algorithm employs a 64-bit key which consists of 56 effective key bits and 8 parity bits. The block size for Triple-DES is 8 bytes and the encryption of the info is performed in 8-byte chunks. As the name indicates the info or message which is to be transmitted is encrypted three times by applying DES encryption method in order to make the data more secure. The implementation of Triple DES is more in now a days. The innovated technology which exists today can be easily cope up with the Triple DES and the feature of the longer key length made 3DES to be the perfect solution for any network engineers. This feature of the longer key length helps in avoiding the shortcut attacks and also reduces the time to break the DES. The procedure which is known as EDE(Encrypt, Decrypt and Encrypt) is employed to increase the key amount of the cryptographic system by using the Triple Pass DES. In the process of triple pass DES teh plain data is encrypted first by using the 56-bit key and the resulted ciphertext is decrypted by using different key and the effect is that the garbage which is again encrypted by the first key. So the procedure for this encryption decryption and encryption is recognized as EDE.


IDEA is one of the symmetric or secret key algorithms which is employed in the process of encryption and decryption. Xuejia and James Massey developed this algorithm and these people participate in Swiss Federal Institute of Technology. This algorithm employs the 128-bit type in order to encrypt the info which are present in the block of each size of 64 bits. This algorithm is recognized as block cipher method. The program and hardware can be implemented by this algorithm. This algorithm is described as the strong algorithm due to feature of the longer key length. The main element length which is utilized by this algorithm is 128 bits. This can help in the secure transmission of the data and to prevent the comprehensive key searches and the other feature is usually that the encrypted text can't be easily decipherable from the plaintext and the main element. So the advanced of security can be provided by IDEA with easy implementation. The reliability and the strength features make IDEA to be used in many industry and banking applications globally.


The abbreviation of RC2 is the Ron's Code which is 64-bit block cipher that was designed by Ron Rivest and the keys which are being used by this algorithm are of variable sizes. It was designed in order to displace DES and the code for this algorithm is not public which is not revealed to anyone. The RC2 is employed by many companies but which is the certified one. The program packages such as Microsoft Windows, Lotus Notes, WEB BROWSER and Netscape Communication's Navigator and Communicator employs this algorithm. The privacy and interpretability between your export versions and domestic versions of products designed to use S/MIME is provided by RC2


This is also one of the symmetric key algorithms created by Ron Rivest and it is employed in many software programs such as Microsoft Windows, Lotus Notes etc. The main element size of this cipher is up to 2048 bits or 256 bytes. That is one of the strong and fast cipher methods and the feature of the stream cipher assists with creating some random bytes and XORs this byte by making use of text. Both different messages which uses the same key with the help of RC4 become weak and so it is useful in condition that both different messages uses the various key.


This is one of the secret key algorithms which can be used for the process of encryption or decryption ad was created by Ron Rivest for the purpose of the security of RSA in the year of 1994. How big is the main element, RC5 data blocks and the amount of rounds are variable in this kind of algorithm. The size of the block ranges from 32 bits, 64 bits to 128 bits and the amount of rounds ranges from 0 to 255 and the size of the key ranges from 0 bits to 2040 bits.


CAST-128 is one of the symmetric key algorithms which was produced by Carlisle Adams in-may 1997. The key length used by this algorithm is variable and varies from 40 bits to 128 bits in increments of 8 bits. The block sizes employed by this algorithm are 64 bits. The data block undergoes the encryption of 12 rounds when the key size ranges up to 80 bits and while the data block undergoes encryption 0f 16 rounds when the key size ranges more than 80 bits The zeroes are put into how big is the main element when the main element size is less than 128 bits and they are added to minimal significant bits before size becomes 128 bits. The input key for an CAST algorithm should be 128 bits. The implementation of this algorithm has been processed up to 3. 3 MB/sec over a 150 MHz Pentium processor.


The computational power keeps growing in leaps and bounds due to the growth rate of two times every 18 months which resulted in the Data Encryption Standard more insecure and also weak to the malicious attacks from the unauthorized users. This resulted in the slow under development of Data Encryption Standard (DES) which is the Federal Information Processing Standard (FIPS). Therefore the National Institute of Standards and Technology have understood the situation and decided to introduce the other standard which will be better than DES which resulted in the introduction of Advanced Encryption Standard (AES). The competition which was held by NIST declared that the AES is the powerful standard than DES which is the powerful replacement of DES. The algorithms which are under competition are MARS, RC6. Twofish, Serpent and Rijndael and your competition declared that the Rijndael algorithm is the best AES algorithm.


This algorithm was created by Daemen and Rijmen. This algorithm is a secret key block chipper and allows the main element sizes of 128, 192 and 256 bit key lengths. The size of the block can be 128, 192 and 256 bots long. The speed of the algorithm is high and it can encrypt up to 8. 8 MB/Sec on the 200 MHz Pentium Processor. The performance and the simplicity of the algorithm made its use to everyone which is compact, fast and has a simple mathematical structure.


As the name indicates that the main element which can be used here is not the same for both encryption and decryption. Here the encryption can be done by only public key and the decryption can be done by only the private key. So the several algorithms can be utilized in this type of encryption however the widely used algorithm is RSA algorithm.


The RSA stands for Ron Rivest, Adi Shamir and Leonard Adelman who are in charge of the design of this algorithm in the year of 1978. The implementation of the public key cryptography is the RSA algorithm. Generally in the public key cryptography one user or person or object has its own public key which is obtainable to any other users and al so one private key which is kept secret with it rather than accessible to any other users. So for the communication in the global world requires only 2n keys where n is the amount of users. The communication or the data transmission between your two users using the RSA algorithm takes place in the following way

The public key which is present with an individual B is accessible by the user A. Therefore the user A obtains the general public key and the encryption of the message occurs with the help of this public key. Then your encrypted message is received by the user B and then the message is decrypted by using the private key which exists with an individual B.


Key Management: The issue of the key management can be easily solved with the help of this algorithm. In secret key encryption or the symmetric key encryption the keys which must allow n entities to be able to communicate is proportional to the square of n. But in asymmetric encryption or the general public key encryption as the necessity for the users is two keys the full total quantity of keys required by 2*n. So there is a linear growth in the number of users and the number of keys. So this feature assists with easy management of the keys when the keys are large in number.

Improved Transaction Security: The other advantage of RSA algorithm other than the key management is the transaction security. The security is offered with the aid of the keys. The security is directly proportional to the number of keys. As the number of keys increases the security provided is more. So every user or person should maintain more than two keys for itself. As the trick key is not accessible or shard with anyone the problem of transmitting the trick key won't happen. The problem of secure channels and the management of the channels won't happen. The public key generally is distributed to everyone therefore there is absolutely no issue of privacy and security. The industry standard for encryption is the RSA. The strength feature of the RSA algorithm made prohibition of its export to the foreign countries.


The RSA algorithm being the very strong algorithm has some weakness that happen to be referred to as follows

Public key factoring: The RSA algorithm has been evolved as the secure algorithm to be utilized which has survived over 20yrs of scrutiny and it is also used widely across the world. The factoring of the general public key is the primary attack of the RSA algorithm which influences the decryption of the message with the aid of the general public key. If this weakness is solved then all the messages can be decrypted with the aid of the general public key.

Cycle attack: The decryption of the ciphertext is performed repeatedly so that the original text can be reformed which requires many volume of cycles to decrypt which results in the slow process and also this is not really a practical attack for the top keys. So despite of all these weakness the RSA algorithm is became a solid algorithm.

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