Implementation of aes and blowfish algorithm

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Special Issue: 03 | May-2014 | NCRIET-2014, Available @ http://www.ijret.org 143
IMPLEMENTATION OF AES AND BLOWFISH ALGORITHM
Chaitali Haldankar1, Sonia Kuwelkar2
1Electronics and Telecommunication, GEC, Goa, India
2Electronics and Telecommunication, GEC, Goa, India
Abstract
Small embedded devices (including smart cards, RFID, sensor nodes) are now deployed in many applications. They are usually
characterized by strong cost constraints. Yet, as they may manipulate sensitive data, they also require cryptographic protection .As a
result, many algorithms have been proposed in order to allow strong security at lower cost than standard solution and lack of
comparative studies prevent a good understanding for these cryptographic algorithms. Thus in this thesis we study the cryptographic
algorithms like AES and Blowfish and compare different parameters and then do further implementation as the implementation of
encryption/decryption algorithm is the most essential part of the secure communication. The algorithms are further considered for
VLSI implementation. The evaluation is performed in terms of encryption speed, the CPU utilization with time and the battery power
consumption. The experimental results specify the efficiency of the algorithms.
Keywords: Plain text, Cipher text, Encryption, and Decryption
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1. INTRODUCTION
Cryptography is the science of information and
communication security. It entered in mass product markets
quite recently and every citizen from developed countries uses
it daily. It is used for authentication and encryption(bank card,
e-commerce, pay-TV), access control (carlock systems, ski
lifts), payment (prepaid telephone cards, e-cash), and may
become the fundamental instrument of democracy with the
advent of e-voting systems. To master cryptographic tools
becomes a requirement for most engineers Cryptographic
Algorithms plays a major role in implementation of encrypting
the data. As the complexity of algorithm is high the risk of
breaking the original plaintext from that of cipher text is less.
Greater complexity means greater security.
Cryptography algorithms are divided into Symmetric and
Asymmetric key cryptography [1]. Symmetric key encryption
use only key to encrypt and decrypt data. Key plays an
important role in encryption and decryption. If a weak key is
used in the algorithm then easily data can be decrypted. The
size of the key determines the strength of Symmetric key
encryption. Symmetric algorithms are of two types: block
ciphers and stream ciphers. The block ciphers are operating on
data in groups or blocks. .Examples are of Data Encryption
Standard (DES), Advanced Encryption Standard (AES) and
Blowfish. Stream ciphers are operating on a single bit at a
time. RC4 is stream cipher algorithm. In Asymmetric key
encryption, two keys are used; private keys and public keys.
Public key is used for encryption and private key is used for
decryption Fig.1 shows the overview field of cryptography.
Fig -1: Overview of field of cryptography
1.1 Various Goals
1) Confidentiality
Information in computer is transmitted and has to be a
accessed only by the authorized party and not by anyone else.
2) Authentication
The information received by any system has to check the
identity of the sender that whether the information is arriving
from a authorized person or a false identity.
3) Integrity
Only the authorized party is allowed to modify the transmitted
information. No one in between the sender and receiver are
allowed to alter the given message.
4) Non Repudiation
Ensure that neither the sender, nor the receiver of message
should be able to deny the transmission.

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5) Access control Only the authorized parties are able to access the given information. 1.2 Basic Terms 1) Plain Text The original message that the person wishes to communicate with the other is defined as Plain Text. For example, Alice is a person wishes to send “Hello Friend how are you” message to the person Bob. Here “Hellow Friend how are you” is a plain text message. 2) Cipher Text The message that cannot be understood by any one or a meaningless message is what we call as Cipher text. For Example, “Ajd672#@91ukl8*^5%” is a Cipher Text produced for “Hello Friend how are you”. 3) Encryption A process of converting plain text into cipher text is called as Encryption. The process of encryption requires two things- an encryption algorithm and a key. An encryption algorithm means the technique that has been used in encryption. Encryption takes place at the sender side. 4) Decryption A reverse process of encryption is called as Decryption. It is a process of converting Cipher text into Plain text. The process of decryption requires two things- a decryption algorithm and a key. A decryption algorithm means the technique that has been used in Decryption. Generally the encryption and decryption algorithm are same. 5) Key A key is a numeric or alpha numeric text or may be a special symbol. The key is used at the time of encryption takes place on the plain text and at the time of decryption takes place on the cipher text. For example, if the Alice uses a key of 3 to encrypt the plain text “President” then cipher text produced will be “Suhylghqw". 2. CRYPTOGRAPHIC ALGORITHMS
There are number of cryptographic algorithms used for encryption data and most of all fall into two generic categories Public key system and secret key system. Symmetric key algorithm is known as secrecy key or shared key algorithm. Because in symmetric key algorithm a shared key does both the encryption and decryption. Only one key is used for doing everything, so the success of algorithm depends on two factors-secrecy of the key and its distribution. Symmetric algorithms are: Data Encryption Standard (DES), Triple DES (3DES), International Data Encryption algorithm (IDEA), Blowfish, Advanced Encryption Standard (AES). Asymmetric key algorithm is also known as public key algorithm. In this algorithm, there are two keys public and private used for encryption and decryption. Public key is used to encrypt the message and private key is used to decrypt the message. Asymmetric algorithms are Diffe-Hellman and RSA Public Key Encryption. Symmetric key technique uses a single key called secret key which uses less mathematics, results in less computation, on the other hand asymmetric key technique uses both public and private keys, results in more processing and consumes more energy. Symmetric key techniques offer better energy efficiency as compared to public key that is why most researches use it for creating MAC in WSN.
2.1 AES The NIST [1] selected the Rijndael algorithm, which was developed by Joan Daemen and Vincent Rijmen, to replace the dataencryption standard (DES) algorithm [2] as the new advanced encryption standard (AES) algorithm [3]. AES is based on a design principle known as a substitution- permutation network. AES has 128-bit block size and a key size of 128,192 or 256 bits [1].AES operates on a 44 column- major order matrix of bytes, termed the state. Most AES calculations are done in a special finite field. The AES cipher is specified as a number of repetitions of transformation rounds that convert the input plaintext into the final output of cipher text. The number of cycles of repetition are as follows: a. 10 cycles of repetition for 128 bit keys. b. 12 cycles of repetition for 192 bit keys. c. 14 cycles of repetition for 256 bit keys. Each round of encryption process requires the following four types of operations: SubBytes , ShiftRows , MixColumns, XorRoundkey. Decryption is the reverse process of encryption and using inverse functions: InvSubBytes, InvShiftRows, InvMixColumns[4]. A simpler way to view the AES function order is: 16 1. Scramble each byte (SubBytes). 2. Scramble each row (ShiftRows). 3. Scramble each column (MixColumns). 4. Encrypt (AddRoundKey). 2.2 Blowfish
Blowfish is a 64-bit symmetric block cipher with variable length key. The algorithm operates with two parts: a key expansion part and a data encryption part. The role of key expansion part is to converts a key of at most 448 bits into several sub key arrays totalling 4168 bytes. The data encryption occurs via a 16-round Feistel network . It is only suitable for application where the key does not change often, like communications link or an automatic file encryption. It is significantly faster than most encryption algorithms when implemented on 32-bit microprocessors with large data caches .The nature of encryption algorithms is that, once any significant amount of security analysis is done, it is very undesirable to change the algorithm for performance reasons, thereby invalidating the results of the analysis. Thus, it is imperative to consider both security and performance together during the design phase. While it is impossible to take all

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future computer architectures into consideration, an
understanding of general optimization guidelines, combined
with exploratory software implementation on existing
architectures to calibrate performance, should help achieve
higher speed in future encryption algorithms.
2.2.1 Subkeys
Blowfish uses a large number of subkeys. These keys must be
precomputed before any data encryption or decryption.
The P-array consists of 18 32-bit subkeys: P1, P2,..., P18.
There are four 32-bit S-boxes with 256 entries each:
S1,0, S1,1,..., S1,255;
S2,0, S2,1,..,, S2,255;
S3,0, S3,1,..., S3,255;
S4,0, S4,1,..,, S4,255.
2.2.2 Pseudo Code of Blowfish Algorithm
begin itemize
Blowfish has 16 rounds.
The input is a 64-bit data element, x.
Divide x into two 32-bit halves: xL, xR.
Then, for i = 1 to 16:
xL = xL XOR Pi
xR = F(xL) XOR xR
Swap xL and xR
After the sixteenth round, swap xL and xR again to undo the
last swap.
Then, xR = xR XOR P17 and xL = xL XOR P18.
Finally, recombine xL and xR to get the ciphertext.
Decryption is exactly the same as encryption, except that P1,
P2,..., P18 are used in the reverse order. Implementations of
Blowfish that require the fastest speeds should unroll the loop
and ensure that all subkeys are stored in cache.
3. COMPARISON OF ALGORITHMS
Table -1: Comparison of algorithms
Algorithm Block Size Rounds Key
AES 128,192,256
Bits
10,12,14
Rounds
128
Bits
BLOWFISH 32-448
Bits
16
Rounds
64
Bits
4. SIMULATION RESULTS
The calculation for Encryption and Decryption speed of each
algorithm for different packet sizes is done. Their
implementation has tried to optimize the maximum
performance for the algorithm. The throughput for encryption
as well as decryption is calculated one by one. Encryption
time is used to calculate the throughput of an encryption
scheme The performance metrics are analyzed in matlab by
(a) Encryption/decryption time.
(b) CPU process time
Table -2: Comparison of algorithms with respect to time in
seconds
algorithm Encryption/decryption
For 64 bits
CPU Time
AES 1.261816 1.54440990
BLOWFISH 0.850568721 0.07800050
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
AES BLOWFISH
CPU TIME
ENCRYPTION
/DECRYPTION
TIME
Chart -1: Comparison of AES and Blowfish
Fig -1: Simulation results of AES-128 bits using Modelsim
Figure 3 shows the simulation results using ModelSim for
AES-128 bit by considering the following inputs.
Plain Text – 00112233445566778899aabbccddeeff
Key Input – 000102030405060708090a0b0c0d0e0f
The following Encrypted output obtained is as shown.
Cipher Key –13111d7fe3944a17f307a78b4d2b30c5
Cipher Text –69c4e0d86a7b0430d8cdb78070b4c55a

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5. CONCLUSIONS The above results show the superiority of Blowfish algorithm with AES in terms of the throughput, processing time. More the throughput, more the speed of the algorithm & less will be the power consumption. Finally we can conclude that Blowfish is the best of all. In future we can perform Hardware Implementation to compare different parameters REFERENCES [1]. Jawahar Thakur, Nagesh Kumar,“DES,AES and Blowfish: Symmetric Key Cryptography Algorithms Simulation Based Performance Analysis,“ in International Journal of Emerging Technology and Advanced Engineering (ISSN 2250-2459, Volume 1, Issue 2, December 2011), pp.6- 12 [2]. E. Thambiraj,G. Ramesh,Dr. R. Umarani , “A survey on Various Most Common Encryption Technique “ International Journal of Advanced Research in Computer Science and Software Engineering , Volume 2, Issue 7, July 2012,pp226- 233 I.S. [3]. S.Pavithra, Mrs. E. Ramadevi “STUDY AND PERFORMANCE ANALYSIS OF CRYPTOGRAPHY ALGORITHMS ” International Journal of Advanced Research in Computer Engineering & Technology Volume 1, Issue 5, July 2012 14, pp.82-86 K. Elissa, “Title of paper if known,” unpublished. [4]. J.Daemenand V.rijmen,"AES submission document on Rijndael", version 2, September 1999Role,

Implementation of aes and blowfish algorithm

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Implementation of aes and blowfish algorithm