Comparison of Various Encryption Algorithms for Securing Data

: Data encryption is the process of protecting information. It protects its availability, privacy and integrity. To write this article we have study about information security using cryptography technique. After the analyzing different techniques of encryption, we are proposing Advance Encryption Standard (AES). The AES has the better security compared others encryption algorithm and prevent data from Spoofing. It is very efficient in both hardware and software.


Introduction
Data Encryption is the process of converting the plaintext into Encoded form (non-readable) and only authorized person/parties can access it.Data security is an essential part of an Individual/organization; it can be achieved by the using various methods.The encrypted data is safe for some time but never think it is permanently safe.After the time goes on there is chance of hacking the data by the hacker.Fake files are transmitted in the same manner as one can sends the encrypted data.There are many algorithms available in the market for encrypting the data.Encryption Key has the major role in the overall process of data.
Fig1 Encryption and Decryption process II.

Methodology
In this article, we have considered Various Encryption Algorithms and Techniques for improving securing data, Information Security using encryption.Comparisons of encryption algorithms on the basis of their performance, key size, efficiency in hardware and software, availability, implementation techniques, and speed.

Summary of algorithms
We compare measured speed of encryption with various algorithms available as standard in Oracle JDK, using Eclipse IDE and then give a summary of various other characteristics of those algorithms.The encryption algorithms is consider here are AES (with 128 and 256-bit keys), DES, Triple DES, IDEA and Blowfish (with a 256-bit key).

Performance
First, the easy bit. Figure 4 shows the time taken to encrypt various numbers of 16-byte blocks of data using the algorithms mentioned.

Fig4 Comparison of encryption times for various common symmetric encryption algorithms [1]
It's important to note right from the beginning that beyond some ridiculous point, it's not worth sacrificing speed for security.However, the measurements will still help us make certain decisions.

IV. Discussion
Some important encryption algorithms are discussed here:

Data Encryption Standard (DES)
It is one of the most widely accepted, publicly available cryptographic systems today.It was developed by IBM in the 1970s but was later adopted by the US government as a national bureau of standards as an official Federal Information Processing Standard (FIPS) for the United States in 1976.It uses a 56-bit key to encrypt the 64 bit block size data.It processes 64-bit inputs into 64-bit cipher-text and algorithm performs 16 iterations.

International Data Encryption Algorithm (IDEA)
IDEA is a block cipher designed by James Massey and Xuejia Lai and was first described in 1991.It uses 128 bit key length which operates on 64 bit blocks.It consists of a series of eight identical transformations based upon bitwise exclusive-or, addition and multiplication modules.It is based upon symmetric cipher and has very weak key design method therefore security level of the algorithm is very poor as compared to the DES.IDEA not becomes so much popular due to its complex structure.

Blowfish
Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in a large number of cipher suites and encryption products.Blowfish provides a good encryption rate in software and no effective cryptanalysis of it has been found to date.However, the Advanced Encryption Standard (AES) now receives more attention.

Triple DES (TDES)
It was developed in 1998 and derived from DES.It applies the DES cipher algorithm three times to each of the data blocks.Triple Data Encryption Standard (DES) is a type of computerized cryptography where block cipher algorithms are applied three times to each data block.The key size is increased in Triple DES to ensure additional security through encryption capabilities.Each block contains 64 bits of data.Three keys are referred to as bundle keys with 56 bits per key.There are three keying options in data encryption standards: All keys being independent Key 1 and key 2 being independent keys All three keys being identical Key option #3 is known as triple DES.The triple DES key length contains 168 bits but the key security falls to

Twofish
It was derived from blowfish by Bruce Schneier in 1998.It is freely available in the public domain as it has not been patented.It is a symmetric key block cipher having key sizes 128,192 and 256 bits used to encrypt the 128 bit block size data in 16 rounds.The algorithm making use of S-Boxes and makes the key generation process very complex and secured.

Advanced Encryption Standard (AES)
It is a symmetric 128-bitblock data encryption technique developed by Vincent Rijmen.The U.S government adopted the algorithm as its encryption technique in October 2000, replacing the DES encryption it used.AES works at multiple network layers simultaneously.The National Institute of Standards and Technology (NIST) of the U.S. Department of Commerce selected the algorithm, called Rijndael (pronounced Rhine Dahl or Rain Doll), out of a group of five algorithms under consideration, including one called MARS from a large research team at IBM.
While the terms AES and Rijndael are used interchangeably, there are some differences between the two.AES has a fixed block size of 128-bits and a key size of 128, 192, or 256-bits, whereas Rijndael can be specified with any key and block sizes in a multiple of 32-bits, with a minimum of 128-bits and a maximum of 256-bits.

It provides following services:
• It is a politically safe decision: the encryption standard of the US National Institute of Standards and Technology (NIST), and the US government reportedly approves AES with 192 or 256-bit keys for encrypting top secret documents.
• Nobody yet has (publicly) a full attack on AES, or a partial attack that is practical (though some impractical partial attacks exist5).• AES is algebraically simpler than other block ciphers: effectively, it can be written as a series of mathematical equations.
• The NSA may have chosen Rijndael as they secretly know how to break it, or secretly estimated that they could develop a way to break it.

IV. Comparison
The techniques have been compared on the basis of that how much: • CPU processing speed for encrypting and decrypting data.
• Speed to generate the key.
• Efficient on the hardware and software in case of implementation.
• The amount of memory required to hold the data in encryption process.
• Number of users accommodated by the model.
• Time required by the model to recover the data in case of key failure.
• Time available to the hacker to produce various types of attacks.
• Complexity of algorithm technique.

Fig5 Comparison of Encryption on the basis of Percentage Efficiency [1]
V.
Formulation and Case study

Case Study
Symmetric (also known as secret-key) ciphers use the same key for encrypting and decrypting, so the sender and the receiver must both know --and use --the same secret key.All key lengths are deemed sufficient to protect classified information up to the "Secret" level with "Top Secret" information requiring either 192-or 256-bit key lengths.There are 10 rounds for 128-bit keys, 12 rounds for 192-bit keys and 14 rounds for 256-bit keys --a round consists of several processing steps that include substitution, transposition and mixing of the input plaintext and transform it into the final output of cipher text.

Rounds
During the encryption process of a message, if the message is not divisible by the block length, then the Padding is used.Padding is the method of adding additional Dummy data.E.g. if the message consists of 426 bytes, then we need 7 additional bytes of padding to make the message 432 bytes long, because 432 is divisible by 16.
Three key sizes can be used in AES and depending on key sizes the number of rounds in AES changes.Standard key size in AES is 128 bits and no of rounds are 10.for AES encryption two sub keys are generated and in 1 st round a round key is added.

Fig7 Explain the Key Size and No of Rounds of AES
For 128 bits plain text and 128 bits key is used and 10 rounds are performed on plain text to find the cipher text.In first step, 10 round keys are generated for each round there is separate round key.But in first round an extra round key which is initial round is added to the round and then transformation is started.Transformation consists of four steps.

Fig8 Shows the Stages of each Round
Round KeyThe Following figure explain all the stages of Encryption from plain text to Cipher text.

Table 1 :
gives a summary of the main features of each encryption algorithm, with what I believe is a fair overview of the algorithm's current security status.