Volume 119 No. 15 2018, 169-183 · obtained by the results which show that AES and Blowfish a...

A Robust Encryption files Approach using Minhash Technique

1 Mehdi Ebady Manaa and Rasha Hussein Jwdha

1College of Information Technology, University of Babylon, Babylon, Iraq.

[email protected]; [email protected]

Abstract

With the fast development of network applications and big data, the encryption and

key generation techniques play an important role in the protection of the sensitive

information for the large organizations that have access to the Internet. Information

security has become an important issue and a source of concern due to increase in the

information such as social media, e-commerce, and banks. Encryption plays an

important role in the protection of information against various attacks using

cryptographic algorithms. This paper comes to overcome the weaknesses in

generating the cipher key for the algorithms and to produce a robust block cipher

using one of the principles for minhash technique in data mining field. The block

keys are generated using the K-Shingle which is mainly used in minhash technique to

convert the text file into a sequence of consecutive words. The length of shingles

depends on the number of K. Minhash technique uses many hash functions to

generate the cipher keys and then to encrypt text files using cipher algorithms DES,

Triple DES, AES, and Blowfish. The robustness of this paper against the attacker is

obtained by the results which show that AES and Blowfish algorithms have excellent

results in term of encryption time, throughput, CPU usage and memory space. The

results are obtained in terms of Encryption time, Throughput, Memory used,

Avalanche effect.

Keywords: Minhash algorithm, Cryptography, Encryption algorithms, Network

Security, Symmetric algorithms.

International Journal of Pure and Applied MathematicsVolume 119 No. 15 2018, 169-183ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

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1. Introduction

The cryptography is the art and science of converting essential information into non-

understandable form that can be not understand by the third part or attacker. The word

Cryptography is derived from Greek origin, Crypto in the sense of secret and Graph in

the sense of writing. The message in this science is converted from readable form into

the unreadable form and then sent to the recipient which he is only authenticated to

decrypt the encrypted message using the agreed key into original message

.

The security criteria are confidentiality, integrity and availability are

conducted using the cryptography to protect the data for the large organization that

have access to the internet. It provides also authentication and non-repudiation. In the

other side, it provides an environment to use in different disciplines such

mathematics, electrical engineering, computer science, and many applications such as

computer password, ATM cards, message integrity techniques, digital signatures,

secure computation, interactive proof, identity authentication, and electronic

commerce . The simple form of encryption is conducted using encryption

and decryption between two parties using shared key between them as depicted in

figure

This form provide a secure communication between Bob and Alice against

adversaries, hackers or attackers. Figure (1) shows the classification of modern cipher

techniques into two categories:

Figure 1: Classification of the Modern Ciphers Techniques.

1. The symmetric algorithms that use the same key in encryption and decryption process. One of the main advantages of the symmetric algorithms is easy to use

and fast to implement but it has disadvantages when use in large networks .

International Journal of Pure and Applied Mathematics Special Issue

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Examples of algorithms that use the symmetric key are AES, DES, 3DES, and others. [1].

2. Asymmetric key encryption (public key encryption) is a type of encryption where

the user has a pair of encryption keys, public key and the private key. The private

key remains secret. The public key share between the parties. The advantage of

this type is that when the message is encrypted using the public key, it can only be

decrypted by the corresponding private key. When a repetition occurs in text we

use mode of operation to avoid repetitions such as CBC, ECB, OFB ...etc. Some

modes require IV (initialization vector) is unique binary sequence for each

encryption operation. The initialization vector is used to ensure distinct

ciphertexts are produced even when the same plaintext is encrypted multiple times

independently with the same key.[2]

In this paper, we use block cipher based on a k-shingle with minhash technique to

encrypt and decrypt the files text that include sensitive information for the large

organization. The K-shingle is used to convert text file into consecutive tokens

depends on the length number of K. the Minhash technique is used to generate many

key for each shingle to generate groups of keys. These keys are manipulated as cipher

keys for the symmetric algorithms such as AES, DES, 3DES, and blowfish that used

in this paper. The remaining of this paper is organized as follow. Section (2) presents

the related work. The cipher method background in section (3). The Key Phase in

section (4). The Materials and Results (proposed system) is illustrated in section (5).

The results and discussion are shown in section (6). Finally. Section (7) discussed the

conclusion of the paper.

2. Related Work

The common related works for this work is illustrated in this part which are many of

the research used symmetric algorithms to encrypt the sensitive data and then use the

same key to decrypt it for original form.

The cost performance evaluation of cryptographic algorithms in term of Encryption

time, Memory used, ,Avalanche effect, entropy and number of bits for encoding

optimality is proposed in [3]. They used many cryptographic algorithms DES, 3DES,

AES, RSA and blowfish. The key is generated by "KeyGenerator" object using

packages in java security and java crypto. They experiments concluded the Blowfish

algorithm is the appropriate algorithm regarding memory used and encryption time.

The DES algorithm is the best in the bandwidth and AES is the best in cryptographic

strength.

The comparison between AES (Rijndael), Triple DES, DES, RC6 and Blowfish

algorithms are conducted using different setting in [4]. They use many evaluation

parameters data size, data type, encryption and decryption time, key size and power

consumption. Simulation results show a comprehensive evaluation for each

algorithm. In the same direction, the paper in [5] applied DES, 3DES, AES, and the


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Blowfish. The ECB (electronic Codebook) mode results show various evaluation for

these algorithms in term of second time for varying input files. The results showed

that Blowfish was the best performance algorithm among the rest of others.

The evaluation of symmetric and asymmetric algorithms such as DES, Blowfish, AES

and RSA is presented in [6]. The comparing algorithms using a number of parameters

such as encryption / decryption time and throughput are conducted for different types

and sizes of data in this experiment. The study has proven that the AES algorithm is

the best in term of the encryption /decryption time and throughput.in addition, The

proposed work in [7] evaluates AES and DES cipher algorithms. The evaluation

parameters are conducted using processing time, CPU usage and throughput using

two platforms in laptop core I5, 2.5 GH CPU on windows 7 and Mac platform for

different data size. The simulation results are evaluated for different sizes of files.

The modified Blowfish algorithm is designed and implemented [8] for networking

and communication application for enhanced network security and defence

applications. They use single Blowfish round instead of many rounds. They uses

Xilinx ISE platform for evaluation the work based on VHDL language. In addition,

the comparisons between two algorithms blowfish and Skipjack are designed and

implemented for encrypting input files of varying contents and sizes. The results show

Blowfish is the best performing algorithm for implementation[9].

The AES algorithm is implemented for five different execution platforms by F. García

in [10]. The main objective of this work is to provide model for the configuration

parameters of AES implementation. In another work, various encryption algorithms

(AES ,Blowfish , Twofish, DES , RSA and Diffie-Hellman) based on different

parameter are compared to choose the best data encryption algorithm by Gaurav and

Aparna[11]. Simulation results are given to show the effectiveness of each algorithm

with the encryption and decryption time, encryption speed and throughput.

3. The Cipher Block Algorithms

The most block cipher algorithms that used in this work are presented in the following

sections. The work in implemented and analysis using Java. In spite of Java complier

is generated Java Virtual Mahine (JVM) that need an interprter to run it inside the

machine code, the cipher algorithms show good results in term of many performance

evaluation and based on Minhash technique.

3.1 Advanced Encryption Standard (AES)

AES was known as Rijndael, is one of symmetric key block cipher developed by

Joaen Daemen, Vincent Rijmen . The block size is 128 bit and it has three key size

128, 192 and 256 bits. The AES rounds are 10 when key size 128, 12 and 14 rounds

with key size 192 and 256 respectively. AES uses key expansion to encrypt/ decrypt

data where key expansion comes before encryption process and before decryption

process. It comes as advance of DES and 3DES[12].


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3.2 Data Encryption Standard (DES)

The DES was published by National Institute of Standards and Technology(NIST) as

first encryption standard. It was designed by IBM based on their Lucifer cipher which

considers as block cipher algorithm with 64 bits key length as standard. The NSA puts

a restriction to use 56 bits as key length for block cipher encryption with 64 bits and

discard 8 bits. The DES is more flexible because it works with different modes such

as OFB, CBC ...etc .

The main drawback of DES is used 56 bits for key length and it was broken by

supercomputer for total 22 hours by DES cracker in 1998 . with the help of

lakh’s of distributed PCs on the Internet . For this reason, it was

modified to a 3DES algorithm, which was used three time key to increase the

strength of the algorithm but it becomes slow.[13]

3.3 Triple Data Encryption Standard (DES )

The enhanced version of DES is the symmetric key block cipher algorithm (3DES). It

comes to strong the block cipher three times the DES. The main problem of 3DES is

slower in performance that DES . The main advantage was to increase

the key size to provide safer for the ciphers data with 112 and 168 bit for block cipher

64 bits length [12].

3.4 Blowfish Block Cipher Algorithm

Blowfish is symmetric key block cipher algorthim with block size 64 bits and various

key cipher size from 32 to 448 bits to protect the encrypted data. It was announced by

Bruce Schneier in 1993. The details of this algorithm can be found in [3]

4. Key generation Method

The main method to generate the key in this work is described by the following

subsections

4.1 K-Shingle

The term of K-shingle is used heavily in document similarity, in this technique,

documents is split into set of tokens depending on the length of k. for example, if the document has the string "The weather is nice and the sky is blue". If we choose k=3, the number of the generated tokens is equal to (n-k+1), where n is the total number of

documents words k is the shingle length. The generated tokens are {“The weather is, weather is nice, is nice and, nice and the, and the sky, the sky is, sky is blue”}. In this

paper, we split the text files into shingles based on the number length of k. then we applied the hash functions (MD5, SHA-512 and SHA-1) for each shingle. The minhash technique is applied for the hashed tokens.

4.2. MinHash Function

The principle of minhash technique is applied in this work. The general form of the

hash function is given in equation (1) .


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where a and b are two random values, x is the hash function value for the tokens and c

is a prime number that is greatly than the maximum number of x [15]. For example,

For example, if we use 4 randomly generated hash functions as shown in equations (2

to 5) respectively for the file size ( ) that has the following text (

)

… (2),

The hash functions in above are used to calculate the value of each hash token for

the file text as depicted in Table(1) below.

Table : The proposed Minhash Work

# The hashed Shingles

(values)

Hash_1 Hash_2 Hah_3 Hash_4


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5. The Proposed System

In this work, we have implemented and compared four block cipher algorithms DES,

3DES, AES and Blowfish. We have implemented algorithms in Java and using files in

different sizes. The key generation is applied based on k-shingles and Minhash. The

evaluation metrics are applied based on the encryption time, memory usage, entropy,

throughput and avalanche effect to evaluate the performance of these algorithms. The

system results are explained in details in the following subsections. The proposed

system is illustred in figure (XXXXXXXXXXXX))

5.1 The key generation phase

At this phase, the K-shingle, hash function and Minhash technique are used. K-

shingle is the process of split the input of the data into substring according to the

specified length of K. The punctuation marks and spaces are removed before applying

the shingling process. The hash function SHA 512 is applied for each generated

shingle. The minhash function is implemented for each hashed shingle. In this work,

we choose 10 hash functions to test the results which are the text files such as .pdf,

.docx, .doc and .xls in different size. The values of a nd b are chosen randomly. The

value of the x is represented the minimum value after applied the 10 hash functions in

randomly setting for a and b values. The output of this stage is many key for each

shingle that used later for cipher process. Figure ( ) illustrates the main steps of the

key generating phase.

Figure 2: The key generation phase for the proposed system


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Input files choose k value prepress text (remove punctuation and double space)

Hashing the Shingles applying Minhash Technique Encryption Phase

Decryption Phase

The proposed system based

5.2. Encryption/ Decryption phase

The generated keys from previous phase is applied for each block size text

. For example, the key 1 is applied to block cipher 1 and key 2 is applied

for block cipher 2 and so on. In the decryption, the same keys are used for the

encypted text to convert it to its original form.

Figure 3:

The main pseudo code steps for the proposed system is illustrated in algorithm (1)

6. The results and discussion

The main criteria to evaluate the algorithms (DES, Triple DES, AES, and Blowfish),

that are implemented in this work, are encryption time, memory usage, entropy,

throughput and avalanche effect.

6.1 Encryption Time

Encryption time is the amount of time that the algorithm is needed to convert data from text to encrypted text depending on the key size and data block size. The less

time the algorithm takes, the better the algorithm is used to embed encryption it in


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other applications such as e-commerce, banking and online transaction processing applications. In this work, we measure the time in milliseconds for different size of

input files in bytes. Table2: The Encryption Time when K=5.

Input Size

(Bytes)

Times in Millisecond

DES Triple DES AES Blowfish

1,164 408510 6104568 143 80

2,492 1930512 78119334 218 192

12,571 90647150 271941450 648 404

114 8882 11429 19 17

24,490 181294300 543882900 1159 464

Figur4: Encryption Time for DES, Triple DES, AES and Blowfish.

It is noticed from the figure (xxxxxx) that the Blowfish and AES take less time for

encryption, while DES and 3DES need time.

6.2 Throughput

The Throughput is calculated by using the equation (xxxxxxxxxxxxx)

Table (xxx) shows the throughput values for different for the fours block cipher

symmetric algorithms.

0

100000000

200000000

300000000

400000000

500000000

600000000

1,164 2,492 12,571 114 24,490

Tim

es

in M

illis

eco

nd

Tie

Files input Size (Bytes)

Encryption Time

DES

3DES

AES

Blofish


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Table3: Throughput Values for DES, 3DES, AES and Blowfish

Input Size

(Bytes)

Throughput

DES Triple

DES AES BlowFish

1,164 0.00284 0.000190 8.13986 14.55

2,492 0.00129 0.000031 11.43119 12.97916

12,571 1.38680 0.000046 19.39969 31.11633

114 0.01306 0.00997 6.10526 6.82352

24,490 0.00013 0.000045 21.13028 52.78017

Figure 5: throughput values

It is noticed in figure (xxxxxxxxxx), the two algorithms Blowfish and AES satisfy the

best throughput values.

6.3 Memory used

The memory usage is the space that is reserved for implementation the algorithms

which is depends on the number of operations in algorithm, key size, initialization

vectors and type of mode operations. It is noticed from the memory usage results that

the Blowfish algorithm is lower consumption of memory, as shown in the table

(xxxxxxxxxxxx).

Table 4: Memory usage for Cryptography algorithms

Input Size

(Bytes)

Memory Used


1,164 4112704 8873136 4603416 4231824

2,492 33792936 201033047 12960288 6498872

0

10

20

30

40

50

60

1,164 2,492 12,571 114 24,490

Thro

ugh

pu

t (b

/Ms)

Files Input Size (Bytes)

Throughput

DES

Triple DES

AES

BlowFish


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12,571 201350208 604050624 78744264 14345040

114 79310016 977580 576632 0

24,490 300762111 904050622 1708720 21142864

Figure (xxxxxxxxxxxx) the superior of Blowfish algorithm than other algorithms in

this work.

Figure 6: Memory usage by Cryptography algorithms

It is noticed for figure (xxxxx) that the Blowfish has the least memory consumption,

while the DES algorithm has the highest memory consumption.

6.4 Avalanche effect

Equation (xxxxxxxx) is used to calculate the avalanche effect by using the hamming

distance.

[3]

It can calculated using the equation (xxxxxxxxx).

It is noted from table (xxxxx) using the equation (xxx) that the AES has the highest

values and satisfy the best results than DES which has the least value.

0

100000000

200000000

300000000

400000000

500000000

600000000

700000000

800000000

900000000

1E+09

1,164 2,492 12,571 114 24,490

Me

mo

ry u

sage

(B

yte

s)

Files Input Size (Bytes)

Memory consumption

DES

Triple DES

AES

Blowfish


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Table 5: Average of Avalanche effect by changing #bits in plaintext

It is cleared that the proposed method satisfy good results when we compare with

results in [16][17] and)[18] in terms of these cipher algorithms.

6.5 Entropy Value

It is calculated using the Shanon law in equation (xxxxxx). It is a measure of

randomness which indicates that the power of the cipher algorithms when hacker tries

to break it.

It is cleared from table (xxxxx) that the AES and Blowfish have the highest values in

randomize.

Table 6: Average of entropy values for cipher algorthims

Input Size (Byte) Entropy


1,164 7.45121 7.45121 7.45121 7.45121

2,492 8.50779 8.50779 8.50779 8.50779

12,571 10.86936 10.87574 10.87574 10.87574

114 3.96981 4.08746 4.08746 4.08746

24,490 10.54109 11.54109 11.54109 11.54109

7. Conclusion

The power of cipher algorithms is depend on many factors the strong of the generated

key or key length for cipher algorithms. This paper comes to propose a robust key

generation based on the principles of K-shingle and Minhash technique. The AES,

DES, 3DESand Blowfish algorithms are implemented in this work based on the

No. of filliped

bits

The Proposed Method (%)

DES 3DES AES Blowfish

1 17.1875 98.437 98.437 93.229

2 17.708 95.312 98.437 95.833

4 0 98.437 100 93.229

19 0 97.368 98.437 92.083

35 33.680 98.958 98.863 93.442

45 26.988 97.5 96.093 92.329

Average 15.927 97.669 98.378 93.357


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minhash technique. We conclude many results in term of many performance

evaluation such as Encryption time, throughput, memory used, and Avalanche effect.

It is concluded that the AES and Blowfish superior the other used algorithms. In the

other results, we conclude that the DES and 3DES satisfy less results in term of

encryption time, throughput and memory consumption where they require a lot of

time to execute. In addition, the obtained results show the Blowfish is more suitable

for the applications that needs speed and AES is better for the applications that need

confidentiality and integrity with highest priority. The strength of all algorithms show

that entropy has equal value which indicate the randomness strength in these cipher

algorithms.

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