Security of the information in any network application is very crucial. Cryptography provides the same with the use of various encryption and decryption algorithm. This paper shows that blowfish is a better choice when compared with DES, 3DES and AES. Also the paper provides the possible improvement in current blowfish algorithm to enhance security.

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Performance Comparison and Enhancement of
Blowfish Algorithm
Vikaram Agraval
Assistant Professor (IT)
B.V.M.Engineering College
V V Nagar
Mital Darji
M.E.(C.E.), student
B.V.M.Engineering College
V V Nagar
_________________________________________________________________________________________________________
Abstract - Security of the information in any network application is very crucial. Cryptography provides the
same with the use of various encryption and decryption algorithm. This paper shows that blowfish is a better
choice when compared with DES, 3DES and AES. Also the paper provides the possible improvement in current
blowfish algorithm to enhance security.
Keywords - DES, 3DES, AES, Blowfish, Throughput.
_________________________________________________________________________________________________________
I. INTRODUCTION
Cryptographic algorithm encrypts the information called plain text into unreadable form called cipher text. This
cipher text is decrypted by the receiver to get back the plain text. Cryptographic algorithm used in this process should
provide Access Control, Authentication, Non repudiation, Confidentiality and Integrity. These algorithms are classified as
symmetric key (private key) and asymmetric key (public key) algorithms based on the keys used for encryption and
decryption. Based on the way of processing plain text it can be classified into stream cipher and block cipher. DES, 3DES,
AES and Blowfish symmetric key block cipher algorithms.
II. PERFORMANCE ANALYSIS
Prof. B.P.Podkar [2] implemented the algorithms in a way that they give maximum performance. He tested them for
performance matrix on Pentium 4 of 2.4 GHz CPU speed with the 4 GB RAM.
Performance matrices are analyzed in terms of throughput by the parameters
1. Encryption/decryption time
2. Power consumption
Throughput = Plain text (MB) / Encryption or Decryption time [2]
Higher throughput indicates higher speed of algorithm and hence less power is consumed. Results are graphed in
Figure 1, Figure 2, Figure 3 and Figure 4 which clearly shows that Blowfish is superior in terms of throughput, power
consumption and processing time.
Fig.1 Throughput of encryption algorithms

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Fig.2 Throughput of decryption algorithm Fig.3 Power consumption (%Battery used)
III. WEAKNESS OF BLOWFISH
Comparison of these algorithms is shown in Table 1. From which we can say here also Blowfish has the superiority.
No attack is known to be successful against it, though it suffers from weak key problem (Bruce, 1996) [2]. It is mentioned
in Table 1 that second order differential attack is a possible crack of blowfish.
Weak keys produce bad S-boxes since Blowfish’s S-boxes are key dependent. There is a chosen plain text attack against
a reduced-round variation of Blowfish that is made easier by the use of weak keys [4].
Also there is some vulnerability in the steps of key generation process [4].
Table 1. Comparison of DES, 3DES, AES and Blowfish
Algorithm Key size
(bits)
Block
size
(bits)
Cracked? Existing Cracks
DES 56 64 Yes Brute force
attack,
differential
cryptanalysis,
liner
cryptanalysis
3DES 112 or
168
64 No Theoretically
possible
AES 128,192,
256
128 No Side channel
attack
Blowfish 32-448 64 No Second order
differential
attack
IV. PROPOSED ENHANCEMENTS
Two approaches are proposed here to improve the security of information and performance of Blowfish algorithm.
A. File splitting and merging
This is the proposed enhancements to increase the security of information.
This approach says that using cryptographic algorithms on slices of data improves the security rather than using a
single algorithm. As shown in Figure 4 file is sliced into parts and then each slice can be encrypted with different
algorithm. Encrypted parts are then merged and sent. At receiver end also cipher text is first spliced into part, decrypted
and then merges to form the plain text.
B. Modification of f-function in Blowfish
As f-function is an important part of the algorithm, improving this function improves the overall performance of the
algorithm. Original function f is defined as [6]
F(X) = ((S1 + S2 mode 232
) XOR S3) + S4 mode 232
The modified f-function is written as [6]
F(X) = ((S1 XOR S2 mode 232
) + (S3 XOR S4 mode 232
))

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The original function is having serial operations of addition and XOR. While the new function has parallel execution of
2 XOR and then addition. It’s quite hard for the eavesdroppers to realize that the f-function is modified and hence
probability of attack is less on comparing with original Blowfish algorithm [6].
Fig.4 File splitting and merging
Fig.5 Original f-function
C. Merits of enhancements
File splitting and merging approach is easy to implement, simple design, infeasible to breach, modular, possible to
modify to work in parallel and hence faster.
Modification in f-function provides better performance and enhanced security. Since our proposed system brings
modification only to the order of execution and no changes is made to the actual functionality, performing cryptanalysis is
not necessary [7].

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Fig.6 Modified f-function
V. CONCLUSION
It is varied that Blowfish is superior in terms of throughput, power consumption and processing time but it has a
possibility of attack due to weak key and S-box generation process. Blowfish can be enhanced to make it even better in
terms of performance and nearer to uncrack able through modifications.
REFERENCES
[1] G. Manikandan, p. Rajendiran, K. Chakarapani, G. Krishnan and G. Sundarganesh “A modified crypto scheme for enhancing data
security,” journal of theoretical and applied information technology, vol. 35, No. 2, January 2012.
[2] Pratap Chnadra Mandal, “Security of Blowfish algorithm”, ijarcsse, vol. 2, Issue 9. September 2012.
[3] Gurjeevan Singh, Ashwani Kr. Singla, K.S.Sandha, “Superiority of Blowfish algorithm in wireless networks,” International
journal of computer applications, Vol. 44, No. 11, April 2012.
[4] Dr. Hala Bahjat Abdul wahab, Dalia Nabeel Kamal, “Modify Blowfish algorithm by increase the randomness for S-boxes,”
unpublished.
[5] Afaf M. Ali Al-Neaimi, Rehab F. Hassan, “New approach for modifying Blowfish algorithm by using multiple keys” IJCSNS,
Vol. 11, No. 3, March 2011.
[6] Kishnamurthy G.N, Dr.V.Ramaswamy and Mrs.Leela.G.H ,“Performance Enhancement of Blowfish algorithm by modifying its
function” Proceedings of International Conference on Computers, Information, System Sciences and Engineering 2006,
University of Bridgeport, Bridgeport, CT, USA. Pp. 240-244.
[7] William Stallings, cryptography and network security, 3rd Ed, Wiley, 1995.