Introduction To Computer Encryption Methods Computer Science Essay

First of all, encoding method is widely used in any distributed system or web system. The encoding methods might supply a really good security characteristics and heighten the company system public presentation.

For most web creative activity company or bank endeavor that necessary this security for service and money minutess. For illustration, the bank require the encoding method to code the user security codification and key while reassign the money through cyberspace. Since early 1977s, the encoding method is no popular in used for system. But, after US authorities acknowledge the encoding method as Data Encryption Standard method for system. Many companies had to the full utilized in service and system.

Encoding benefits in secure informations transmit and better image retrieval from client. So, many companies have emphasized their feedback service and company image towards client in the web system today. It is because client feedback is critical functions to derive an chance to do a concern. Why I said so, because client feedback act as concealed power or free advertizement to force or impact the other clients determination. These feedbacks act as a critical information for develop selling and production program. The services besides able to better and recover a clear way from client feedback or else company may non able to clear up and understand the position of services from clients.

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However, Customer feedback is flexible. It can be positive or negative, therefore it can force the company to success and it besides can force the company to failure. That is why companies nowadays so concentrated on the encoding services. In order to, recover clear and dependable information from client feedback. We have to use some security characteristic to command user repeatedly posting with the same remark, else it may act upon the quality of feedback analysis.

Next, if the advertizement is post without under controlled by web decision maker, the web site content might misapply for other intent. Therefore, a secure feedback informations can impact the quality of web site content. Thurs, to guarantee the informations feedback that in non-overflow state of affairs and the user informations do non easy hacked by unknown user, web decision maker might command the user handiness, authenticate the user watchword, and utilize a standard algorithm to code the input informations.

Due to the information protection emphasize for user handiness, hallmark and payment dealing, the sweetening of informations protection is to utilize encoding method to adhering or code the information off from interloper. The most common techniques used in the web system, which are mandate and hallmark. Even there is common and simpler manner but they are utile. For mandate technique, it can able to command the user handiness that to forestall unauthorised informations usage by other and grant authorized user to entree. Next, for hallmark technique, it able to formalize the user individuality and watchword earlier proceed to following direction.

Basically, these two mandate and hallmark informations security techniques are non adequate strength for forestalling interloper. So, the web system must able to code the informations while executing waiter control in directing informations through cyberspace. For illustration: when users enter the recognition card security codification and watchword to the web page, it must be able to incorporate an encoding criterion algorithm to transform the user informations into cypher text.

Few operation and algorithm in item below statement, the encodings can custom-make by ain behaviour or follow standard algorithm provided. The address of professor said that different encoding method or algorithm used in different state of affairs of the system and services, where he suggestion the informations encoding criterion ( DES ) procedure is suited for common web system and suggested to execute ternary DES or progress encoding criterion ( AES ) for highly of import informations, such as banking minutess or exchange stock transmittal.

Overview for encoding

Definition of Cryptography or Encoding

Cryptanalysis refers to an algorithm and mathematical computations that transform information into encrypted signifier and frailty versa for decoding. The basic procedure of informations transform called informations encoding and informations decoding. Encryption require to trip an algorithm strategies to change over the field text into non-readable signifier is called cipher text. In contrast, informations reserving procedure through a specific algorithm mechanism to return the original clear text signifier which the procedure called informations decoding ( Roy F. Van Buren 1990, pp.1-2 ) ( Miles E. Smid, Dennis K. Branstad, pp.4-5 ) .

Degree centigrades: UsersDermajassDesktopData Encryption.jpg

Figure 2.1 Basic Data Encryption ( Buren, 1990 )

Symmetric Cryptography

Symmetric cardinal cryptosystem is interchanging the secret key to code or decode the information between waiter and client. The secret key will utilize together with plaintext and convert to code text for informations encrypt and frailty versa. Symmetrical encoding is moderately fast procedure comparison to Asymmetric encoding. It because symmetric encoding generate lower operating expense on the system resources. Other than that, it is easier to implement to the environment. However, symmetric key cryptanalysis require parties to code and decode informations by interchanging the secret key, why this is a disadvantage for the symmetric encoding, it is because this is a opportunity for an aggressor or interloper can detect the through mistake or during constitution of the cardinal understanding to recover the exact key usage for this encoding or decoding procedure. Example of Symmetric cypher system: DES, AES/Rijndael, IDEA and etc. ( Aladdin, 2008 ) ( Abd Rahim Mat Sidek & A ; Ahmad Zuri Sha’ameri, 2007 )

Asymmetric Cryptography

Asymmetric Cryptosystem is require two mutualist keys for procedure which one populace key that allow to merely administer to public and another one is private key that ne’er portion to anyone. It is a scalable cryptanalysis and does non necessitate much disposal to command. Besides that, it is unafraid with sufficient long keys and easier for up to day of the month execution. However, Asymmetric cryptanalysis is slower than symmetric cryptanalysis because it uses combination of symmetric cypher to impact the public key. So that it requires to treat few measure to code the existent message. The brief illustrations of Asymmetric cryptanalysis where user directing a message from the beginning to the finish, asymmetric cypher system will code the message with public key. While the message directing to finish, the message content of encrypted key ( private key ) , public key and messages. Once arrive the finish, the receiver can utilize the private key for fiting before decrypt the messages. Example of Asymmetric cypher system: RSA, Diffie- Hellman, El-Gamal and elliptic curve and etc.

( Aladdin, 2008 ) ( Abd Rahim Mat Sidek & A ; Ahmad Zuri Sha’ameri, 2007 )

Professionals and Cons of symmetric

There are the advantage and disadvantage for both Symmetric cyphers and Asymmetric cypher. For the benefit of symmetric cypher is running a faster velocity of procedure during encoding or decoding comparison to other encoding technique. But symmetric cypher requires pull offing a legion Numberss of keys for exchange key if all parties need to interchange the key for encoding before they decrypt it data, else will be increase the hazard to compromise because people holding possible to acquire the same key. For illustration, if usage symmetric cypher, it require to keep the direct relationship between the parties, so that to forestall the same cardinal generate, this cypher methodological analysis require good cardinal direction and else will do failure of communicating.

( Aladdin, 2008 ) ( Abd Rahim Mat Sidek & A ; Ahmad Zuri Sha’ameri, 2007 )

Professionals and Cons of asymmetric

For Asymmetric cypher has benefit in cardinal exchange while RSA algorithm trusted in usage for electronic commercialism protocols to direct the massages from client host to server host without know who are the individual, so in this instance keys is non necessitate the same. However, it is hard to implement and necessitate powerful hardware to back up all the manner, so that clip devouring for asymmetric methodological analysis.

( Aladdin, 2008 ) ( Abd Rahim Mat Sidek & A ; Ahmad Zuri Sha’ameri, 2007 )


In decision, there are benefits and drawbacks to utilize different cypher methodological analysis. So that parties must use or take the cypher methodological analysis as suited for their demand in the right state of affairs. Nowadays, they combine the cypher methodological analysis together to set up the communicating with addition efficiency. For illustration, they encrypted the massage with symmetric key which ready to direct or for dealing. After that, the symmetric key encrypt once more with the recipient public key to direct over the web to the receiving system. Once the receiving system received the massage, receiver need to decode the symmetric key with the private key and utilize its end product to decode the massage.

Block Cipher

Block Cipher is a method to code the informations in block state of affairs where either symmetric or asymmetric cryptanalysis used this block cypher operation manner. The key will be generate or encrypt in a fixed size block. For illustration, a message demand to direct along the web, where apply barricade cipher operation will interrupt a message in to fixed size block ( 64 spots or 128 spots each block ) if the message consist of n spots. A message will one to one function and substitution send to the receiving system.

The encoding of the block cypher neither process applied in neither multiple nor complex unit of ammunition of spot displacement, XOR procedure, substitution and permutation of plaintext and cardinal spots. In other side for decoding of block cypher might frailty versa process. Block cypher able to supply effectivity of confidential and it let to retrieve some portion of field text from cipher text if the key accidently losing or damaged.

( Abd Rahim Mat Sidek & A ; Ahmad Zuri Sha’ameri, 2007 )

Stream Cipher

Stream Cipher is a method to confusion the watercourse cypher because the plaintext encrypt one spot or one byte at a clip and the character or spot is independent of each other. Stream cypher are more complexity building and able to supply high velocity procedure. It is high velocity because it is transmutation of consecutive spots and implemented by XOR procedure with the running key during encoding or decoding.

There are two types of watercourse cypher which are synchronal watercourse cyphers and self-synchronizing watercourse cyphers. For Synchronous watercourse cypher, a cardinal watercourse can bring forth independent for plaintext and ciphertext that generated by a watercourse of pseudo random figures. the key generated by that is called keystream, it will unite together with plaintext or ciphertext to code or decode the messages. For ego synchronising watercourse cyphers is known as asynchronous watercourse cypher, it benefit in easier to retrieve dropped informations or information added to a watercourse of message during the dealing. It will non easy motivate an mistake if there is a individual figure dropped except n plaintext figures mistake.

( Abd Rahim Mat Sidek & A ; Ahmad Zuri Sha’ameri, 2007 )

Professionals and cons of Block cypher

There are the advantage and disadvantage for Block cypher and Stream cypher. For the Block cypher benefits that to able easiness standardize and reclaimable key allowed which average informations information can treat in a block ( 8 byte or 64 spots ) as usual with the same end product. Therefore, cardinal direction much easier. Following advantage of Block cypher is interoperability that able to back up in many platform comparison to stream cypher.

For the disadvantage of Block cypher is losing one spots of block, which might retrieval wrong informations during decoding procedure. Other than that, the same plaintext block might code to the ciphertext ever, this may ensue in reiterating generate the same ciphertext block. So that to get the better of this state of affairs is to use IV for informations encoding procedure. ( Bernadette Ebene, 2010 ) ( Borka Jerman-Blazic, 2001 )

Professionals and cons of Stream cypher

For the advantage of watercourse cypher is faster procedure which work on information spot by spot with less codification to implement comparisons to barricade cypher needed block by block procedure. Due to this point, it is faster than block cypher, so stream cypher largely use in existent clip system. However, the cardinal generate by keystream is disposable ( one clip tablet ) which mean it will use one clip and discard after used. This is disadvantage because hard for cardinal direction. Furthermore, even through watercourse cipher drop the key after used, but it still possible two same keystream may used. It this state of affairs, information can uncover to other. ( Bernadette Ebene, 2010 ) ( Borka Jerman-Blazic, 2001 )


In decision, the advantage and disadvantage reference supra, as the few writer ( Lawrence Miller, Peter H. Gregory, 2009 ) ( Bernadette Ebene, 2010 ) ( Borka Jerman-Blazic, 2001 ) suggested that Block cypher manner is good to use in computing machine package application, it may work efficiency and more secure. Block cypher applied in computing machine package application such as database system, watchword encoding system and etc.

For the watercourse cypher, they suggested to use on the existent clip application or interaction application because it is faster procedure velocity and a spot of block girl or harm might non able to act upon the whole procedure of encoding or decoding. Therefore, watercourse cypher can fulfill the user and transmit informations without hold. Stream cypher applied in existent clip application or interaction application such as web system, voice conferencing, phone call system and etc. ( Lawrence Miller, Peter H. Gregory, 2009 ) ( Bernadette Ebene, 2010 ) ( Borka Jerman-Blazic, 2001 )

Block Cipher manner of operation

Mode of operation

Encoding or decoding algorithm


Ci = Ekey ( Pi ) ; Pi = Dkey ( Ci )


Ci = Ekey ( Ci-1 ) aS• Pi, C0 = IV

Pi = E key ( Ci-1 ) aS• Ci, C0 = IV

Complete blood count

Ci = Ekey ( Pi aS• Ci-1 ) , C0 = IV

Pi = Dkey ( Ci ) aS• Ci-1, C0 = IV


Ci = Pi aS• Oi ; Oi = Ekey ( Oi-1 ) , O0 = IV

Pi = Ci aS• Oi ; Oi = Ekey ( Oi-1 ) , O0 = IV


Ci = Ekey ( IV aS• CTRi ) aS• Pi

Pi = Ekey ( IV aS• CTRi ) aS• Ci

The Block cypher manners of operations ( Sarah M. Diesburg, 2008 )

Types of Block cypher operation manner

Electronic Codebook Mode ( ECB )

Cipher Block Chaining ( CBC )

Cipher Feedback ( CFB )

Output Feedback ( OFB )

Counter ( CTR )

Block Cipher Mode Of Operations.docx

Comparison of Block Cipher Mode of Operations

Electronic Codebook Mode ( ECB )

Cipher Block Chaining ( CBC )

Cipher Feedback ( CFB )

Output Feedback ( OFB )

Counter ( CTR )

Algorithm method

One to one relationship.

Process velocity

Faster, running in parallelize

User friendly



Chain dependences


Encryption informations

Decryption informations

Perform another XOR map on receiving system side


Block Cipher Algorithms – Diethylstilbestrol

Introduction of Data Encryption Standard ( DES )

Since prior 1970s, the informations encoding is non much popular apply into the equipment for security propose. For the military and intelligence endeavor will use their ain usage informations encoding method or alone codifications into equipment for communicate internally. Other than that, some organisation is purchased the cryptanalytic equipment under contract to U.S. authorities, so that all the information was itself classified. Due to the organisation purchased encoding techniques difference from each other. Therefore, it is hard to protect electronic information in both client and waiter and they might possible have incompatible information during transmittal over web and computing machine system.

However, information has non a criterion to protection the of import informations and there is no a standard information encoding available during early 1970s. Therefore, The International Business Machines Corp ( IBM ) interested and perceived demands to develop a plan in cryptanalysis for protect information during transmittal particularly for transmittal for dispensing of money. Therefore, IBM invites several universities who involvement in mathematics of cryptanalysis for thought retrieval. However, there was limited expertness on cryptanalytic algorithms cognition ‘s. They were sing cryptanalytic algorithms as rational challenge ( Miles E. Smid & A ; Dennis K. Branstad, pp.5 ) .

On 27 August 1974 and 17 March 1975, IBM proposed the cryptanalytic algorithm to National Bureau of Standards ( NBS ) for solicitation in the federal registry ( Miles E. Smid & A ; Dennis K. Branstad, pp.5 ) . But the building ne’er O.K. . Until on 15 January 1977, The Data Encryption Standard ( DES ) specifies two Federal Information Processing Standards ( FIPS ) approved this Cryptographic algorithm as required by FIPS 140-1. When integrate with American National Standards Institute ( ANSI ) X9.52 criterion. Because of the DES may supply full description of the mathematical algorithms for coding and decoding binary codification information ( Reaffirmed, 1999 ) .

Once DES approved, IBM was issued this Data Encryption Standard ( DES ) adopted around the universe. Besides that, the demand for this DES must be reviewed by NBS five old ages since its acceptance ( Alejandro Hevia, Marcos Kiwi, 1999 ) . As reference above, DES may dwell of Data encoding algorithm and Triple Data Encryption algorithm ( TDEA ) which described in American National Standards Institute ( ANSI ) X9.52 criterion. Since so, The DES algorithm has been adopted by whoever that might desire to protect their organisation informations. For illustration these two private organisations besides adopted DES algorithm such as American National Standards Institute ( ANSI ) and American Bankers Association ( ABA ) . ( Buren, 1990 )

Data Encryption Standard ( DES ) Algorithms

The DES algorithm is a symmetric or private-key cryptosystem. It is because the parties must maintain secret for the 64 spots DES key in the progress. DES for informations encoding can be encrypt 64 spots plain text into 64 spots cipher text end product. For more item, the DES divide the parties input into two halves and it merely take 56 spots information from the DES key entered by user ab initio that 56 spots of information called active key and another 8 para spots is non use by DES. There is a 2^56 possibility of cypher text values during encoding procedure. Which mean different input of active cardinal makes different cipher text and there is no information clang occurs during procedure.

Degree centigrades: UsersDermajassDesktopDES encoding process.jpg

Figure 2.2 Brief DES Encryption Process

Data Encryption Standard holding three procedures phases which are fixed initial substitution, loop of substitution and opposite of the initial substitution. First manner of DES will obtain the active cardinal 56-bits of field text and operation of commuting harmonizing to initial substitution IP. Once the first phase is done, the spot of consequence will thoroughly use to following two phases. Following Stages, DES will acquire the first phase spot of consequence and reiterate the procedure on it map continuously, Last phase will discourse ( concluding substitution FP = IP-1 ) the 2nd phase bits 16 times to the halves. DES consist the F-function along with the unit of ammunition bomber key. The group of bomber key called Key agenda KS and it will set up the bomber key to act upon the substitution. The two halves will trade one time the end product of map ( XORed ) came out. Highlight on the Initial substitution IP and concluding substitution FP have no cryptanalytic consequence on Electronic codification book ( ECB ) or cipher block chaining ( CBC ) . There is more apprehensible on the figure 2.2 and figure 2.3 Data Encryption Standard Encryption Process that have been shown ( K. Srinathan, C. Pandu Rangan, M. Yung, 2007 ) ( Alejandro Hevia, Marcos Kiwi, 1999 )

Degree centigrades: UsersDermajassDesktopCapture.JPG

Figure 2.3 General construction of the Data Encryption Standard

DES algorithm can run in several manners, such as Electronic Code Book ( ECB ) , Cipher Block Chaining ( CBC ) and Cipher Feedback ( CFB ) . Parties might see twice if they traveling to run all block cypher manners into the system. There are non perfect for every manners, they might hold it ain strength and failing. Highlighted the job if parties do non use decently, it may do failure or may be even worse than no security. ( Buren, 1990 ) Therefore, parties should pick the proper block cypher operation manner for its ain demand to work effectivity.

Introduction of AES or Introduction of Blowfish

Introduction of RC4 symmetric key watercourse cypher

Introduction of RSA Asymmetric Block Cipher

Introduction of ElGamal Asymmetric Block Cipher


Comparison between methods




Why I apply this method and why non?


Link to project

I plan to use encoding technique and implement a strong privateness protection security system for our concluding twelvemonth undertaking. I wish to hold a secure information for user and I besides wish to command the advertizement that judgement by client feedback. Example: Web decision maker allow to cancel the advertizement, content posted by member, if there are incorporating lowest evaluation or hapless public presentation commented by member within one month.

Concluding Decision


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