Multimedia Content Security with Random Key ...

Multimedia Content Security with Random Key Generation Approach in Cloud Computing Md. Habibur Rahman, Nazrul Islam, Mehedy Hasan Rafsan Jany, Shariful and Mohammad Motiur Rahman† Department of Information and Communication Technology † Department of Computer Science and Engineering Mawlana Bhashani Science and Technology University Santosh, Tangail-1902, Bangladesh E-mail: [email protected], [email protected], {rafsan.mbstu, robinmbstu12, † mm73rahman}@gmail.com Abstract—The cloud computing offers high scalability, confidentiality and the easy accessibility of the information over the Internet. Though the conventional encryption system provides security, the most concerned issue is the regular side channel attack for capturing ones sensitive and cofidential image, audio and video. A malicious Virtual Machine (VM) besides a targeted VM can extract all information. Thus, this paper implements a double stage encryption algorithm for multimedia content security using random key generation approach. The first stage encrypted multimedia content into ciphertext-1 using symmetric public key. The ciphertext-1 is again encrypted in the cloud using a randomly generated asymmetric private key. If anyone gets the cipher text, he could not extract the encryption key to recover the multimedia contents. Low complexity and easy implementation make the proposed algorithm widely applicable safeguard in the cloud computing. Keywords—Cloud Computing, Multimedia Security, Cryptography, Encryption, Decryption.

I.

I NTRODUCTION

Cloud computing is the freedom of processing and storing data of the consumers in a third party data center using the remote computing resources over the Internet. The cloud is actually a well-equipped universal network structure allows access to a shared pool of computing resources over the Internet and permits online consumers to perform various tasks with the data. No matter for the consumers where the hardware and software or the application is operating, they only need to have a simple device that can simply operate with the cloud. The consumers pay much less for the cloud and have no maintenance liabilities. Many business companies are moving to the cloud. The ability to do multitasking operations lets the cloud be a challenge for the Information Technology (IT) enterprises. The cloud is the combination of three potential services. The three key cloud services are termed as: Infrastructure-asa-Service (IaaS), Platform-as-aService (PaaS) and Softwareas-a-Service (SaaS). In IaaS, the cloud provider supplies Virtual Machines (VMs) and storage on which consumers can build and run applications. Virtual Machines (VMs) are a set of virtualized infrastructural components[1]. The PaaS offers third party services like operating system, programming environments and web servers, whereas SaaS offers different application software. The four popular cloud deployment models for the consumers are: private cloud, public cloud, hybrid cloud and community cloud. Public cloud environments are

accessible by multiple renters, whereas the private clouds are decorated with virtual resources for particular organization only. Hybrid cloud is the composition of public and private cloud and community cloud is dedicated to several groups. Though the private cloud is protected by that particular organization, the rest have data risk and security issues [2], [3], [4]. Moreover, cloud preserves these data, multimedia contents to a large data center [5], [6]. A third party manages the data and multimedia contents and has the liabilities to make certain for the protection of the data and multimedia contents and provide uninterrupted services. Unless there may arise a security question and trustworthiness of third party [7], [8]. Besides the third party deliberately or inadvertently discloses the data or the side channel attacker extracts the data or multimedia contents after placing a malicious VM beside the targeted [9], [10], [11]. At present, the most dealing issue is the security of the cloud, especially the data and multimedia contents such as image, audio and video. Several studies have been done on the security of the multimedia contents in the cloud and decrease the side channel attack [12], [13], [14]. These studies focused on the combination of two different algorithms and generate a security key for consumers as a key to access the cloud. These drawback let us to implement a double stage encryption algorithm for the security of multimedia contents against a negligent third party and side channel attack. This paper implements a double stage encryption algorithm for the security of multimedia contents using a randomly generated key and the 94 bit converter. The randomly generated key is the remarkable feature that makes the second stage encrypted data unbreakable not only for the attackers but also for the system administrator. Thus the paper provides more security of the multimedia content in the cloud. The structure of this paper is as follows. Section II is provided with the related work based on the cloud computing research activities held recently. Section III is described the research methodology. Section IV is illustrated the proposed algorithm. Section V evaluates the performance to show that results meet up with designs objectives. Section VI concludes the paper with future work. II.

R ELATED W ORK

At present, the security of the multimedia contents such as image, audio and video becomes a rising issue. Edward

J. Delp has concerned some security issues based on the multimedia cloud for the next century [15], [16]. represented a survey on recently performed research activities on multimedia security and intersected four burning questions such as data integrity, data confidentiality, access control and data manipulation. They encouraged newer researchers to explore the exciting cloud computing field. The paper [17] showed various vulnerabilities, threats and attacks that hindered the more adoption of emerging cloud and identified some future challenges. Another study proposed taxonomy of security in the cloud layers and represented the current status of security in the rising cloud computing [18]. The proposed known-plaintext attack can successfully access the encryption key and visualize the data stored in the cloud server [19]. Several studies have been done on the security of the multimedia contents in the cloud [20], [21]. The paper [20] replaces the DES algorithm by the AES algorithm due to the inbuilt scarcity of strength and combined the AES with the RSA. Priyanka and Amandeep also proposed an advanced algorithm combining the RSA with two fish [21]. These studies focused on the combination of two different algorithms and generated a security key for consumers as a key to access the cloud. The mitigation of the side channel attack was shown and the proposed algorithm focused only on the two prime numbers [22]. The above study leads us to implement a double stage encryption algorithm for the security of multimedia contents against a negligent third party and side channel attack. The proposed randomly generated key algorithm produces every time a unique symmetric key that lets the data be encrypted successfully. III.

R ESEARCH M ETHOD

A literature review is performed to find out an effective algorithm having minimum complexity and widely applicable cloud security for the multimedia contents against the side channel attack. Since it is more dificult to stop or identify the side channel attack, hence the double stage encryption allows cipher text to store in the VM and double stage decryption transmits the original data from the VM. Based on the literature study the required languages, tools and hardware are selected to develop the proposed algorithm. C++ and Java are the chosen languages and Code Blocks and Netbeans are the chosen compilers. First the multimedia content stored in a file. The file is encrypted in ciphertext-1 after executing the Java code in Netbeans. The ciphertext-1 is stored in another file. Secondly, this file is encrypted again using a randomly generated key and the 94 bit converter into the ciphertext-2 after executing the C++ code in Code Blocks and stored in the cloud or virtual machine. The decryption process is at the same but reverse we have done before for the encryption process. An Intel Core-i5 based workstation is chosen for practicing the proposed setup. The setup is tested several times for providing the best security. IV.

P ROPOSED A LGORITHM AND I MPLEMENTATION

This section describes the implementation plan that performs the better security for multimedia data against side channel attack in cloud computing. The whole process is

Encryption-1 Multimedia Contents

Encryption-2 Cipher Text-1

Symmetric Encryption Key F

Fig. 1.

Decryption-1 Cipher Text-2

Asymmetric Encryption Key Ri

Decryption-2 Cipher Text-1

Asymmetric Decryption Key Ri

Multimedia Contents Symmetric Encryption Key F

Block Diagram of the Algorithm

shown in the block diagram in a short. The encryption and decryption process was done by double stage. At the first stage the multimedia content are encrypted by the conventional encryption process (DES, AES, RSA) using symmetric key. In the second stage the encrypted ciphertext-1 is then again encrypted by the random generated asymmetric key thus produce ciphertext-2. In the decryption stage the encrypted ciphertext-2 is decrypted by the asymmetric key in the first decryption process. Thus produced the ciphertext-1. The ciphertext-1 is then decrypted by symmetric key method (DES, AES, RSA) and regain the original multimedia content. Since the conventional encryption process the key is symmetric the attacker can easily be known the encryption key and retain original multimedia content. In the proposed encryption method the key is randomly generated and the Key exposition possibility is low. Thus, the method provide more strong than the conventional encryption algorithm. A. Test bed Setup In order to find out the multimedia content security in cloud computing an experimental setup was established having an Intel Core i5 based workstation for implementing the proposed algorithm. The Code Blocks and Net beans are the two wellknown environment for executing C++ and Java languages respectively. Second, Code Blocks-12.11 and Netbeans-8.0.2 are installed in the selected workstation. Then the setup was tested severally. B. Proposed Design The cloud is a server-client model and the server system consists of agent module, security module, analysis module and database. Though the conventional cloud model has single encryption and decryption process, the proposed cloud security model has double encryption and decryption model. In the security module, the content manager introduces the cloud contents double encryption processes (Encryption 1 and Encryption 2). The Encryption-1 is usually provided by all cloud architecture and produces ciphertext-1, the proposed Encryption-2 is an attachment based on the architecture in paper [23], [24] to secure the cloud data using randomly generated key and convert the ciphertext-1 into ciphertext-2. The randomly generated key is unknown to the content manager too. In the client, the decrypt processor has double decryption processes (Decryption-1 and Decryption-2) and content player. The proposed Decryption-1 is decrypted by random key and converts the ciphertext-2 into ciphertext-1. The Decryption2 finally converts the ciphertext-1 to multimedia contents using symmetric key. Without the randomly generated key, the Decryption-1 process is impossible and thus the proposed architecture gives eficient security. The Encryption-2 and the Decryption-1 process is based on the random key generation

Security Agent Decryption-1

Client

Decryption-2 Contents Player

Cloud

Transaction

Interaction

Virtual Networks

Agent Module Contents Manager Security Module Encryption-1

Virtual Servers Virtual Storage

Encryption-2 Analysis Module DB

Analysis Processor

DB

DB

Multimedia Contents

Fig. 2.

Proposed architecture of the algorithm in cloud.

shown by the origin color in the system server and the client to the figure. C. Encryption Process While encrypting the multimedia data into ciphertext, the ciphertext-1 has been stored into a file. That has been used for the second pass encryption to generate the ciphertext-2. When the ciphertext-1 generated, a randomly generated asymmetric key has been used for the encryption. Then the encrypted data stored in the cloud. In cloud computing, grabbing the user data from attackers is a dificult task. This paper is about to ensure the security of the multimedia user data. In the first encryption Start Read Cipher Text-1(N) Generate a random prime Number (P)

Calculate M=P*N

Calculate K=94-bit conversion (M)

Calculate S=P%N

Add K as Cipher Text-2

Yes

Ciphertext-1 remains? No Write Cipher Text-2

End

Fig. 3.

Flow Chart of Encryption Operation

process, the multimedia data is converted into cihertext-1 using public symmetric key. Then for the second encryption process, a random prime number (p) is chosen. The ciphertexts are read character by character. In each pass a single character (n) is multiplied with the prime and converted the result into (m) to the 94-bit format. The converted value is then stored in the cloud. A separator is then added with that value. The 94bit format is the set of printable character having the ASCII value from 33 to 126. To prevent from generating the next prime location from out of range, the prime number (p) is mod by the character (n) and stored the result as (s). The location of the next random prime is the lower index of the mod result (s). A prime array is used to generate the random prime. On the second pass the prime array is rearranged by moving the prime number onto the first location of the array. The procedure ensures that selected prime is always random. With every pass of the encryption process the separators are programmatically generated that will help to find the random prime at the time of decryption. Until remaining the ciphertext2 the procedure is continued. The entire procedure of the proposed encryption algorithm is described in the pseudo code. The pseudo code takes a string as input and processes the string according to the encryption algorithm. Then the string is converted into ciphertext-2 and stored in the cloud. The pseudo code for this operation is: ENCRYPTION-PROCEDURE (String str) 1 len := str.length 2 p := Random (prime) 3 for i=1 to len 4 n := str[i] 5 k := 94-bit-converter (p*n) 6 PRINT ”k” // k as a ciper text 7 s := p mod n 8 p := s-1 9 end After completing the whole encryption process of the ciphertext-1 into the ciphertext-2 (see Figure 3) the encrypted data is stored in the cloud. D. Decryption Process In the decryption process (see Figure 4) at first, the cipher text each character is read sequentially one after another and add them to the temp (temporary variable) until found the separator. A character out of 94-bit converter is treated as a separator. By using the separator the random prime (p) is regenerated using at the time of encryption. Then the temp is converted into a decimal value (v). The value is then divided by the prime (p) and regained the desired ciphertext-1 (n). The ciphertext-1 is then stored in the temporary string until the ciphertext-2 remains. The desired output strings are then written to the targeted file and stop the decryption process. Again decrypting the ciphertext-1 for the second step the multimedia data is finally recovered. The pseudo code for this operation: DECRYPTION-PROCEDURE (string cp) 1 len := cp.length 2 t := charValue (cp[0]) 3 p := prime[t-1] 4 for i=0 to len 5 set k := cp[i] 6 if separtor == false

A. Random Key and Robustness

Start

Read Cipher Text-2(K)

Separator = True?

No

Temp = Temp + k[i] i=i+1

Yes Generate a random prime Number (P)

Evaluate V = Decimal (Temp)

Calculate N=V/P

Add N as Cipher Text-1

Yes

Ciphertext-2 remains? No Write Ciphertext-1

End

Fig. 4.

Flow Chart of Decryption Operation

7 temString := temString + k 8 else v := temString 9 n := v/p; 10 str := str + n 11 temsSring := NULL 12 t := upperPos (p mod n) 13 p := prime[t-1] 14 end 15 return str

E. Complexity Analysis The proposed algorithm complexity is calculated considering the variable elementary operations and neglecting the fixed elementary operations. Several operations are taking place in the algorithm. Generation of random prime does not depend on the length of the text. Generating the random number does not have any impact on the execution time. The asymptotic notation of the encryption algorithm is: O (log n + n log n ) , where n = number of ciphertext-1. The asymptotic notation of the decryption algorithm is: O (log c + c log c ) , where c = number of ciphertext-2. V.

The conventional encryption algorithm, symmetric key is used for calculation of encryption decryption technique to convert a normal text into ciphertext or vice versa. Using this method the ciphertext remains same for diffrent pass. For above explanation considered the RSA algorithm as an example. Suppose the original text is ABCDEF and the fixed key value for RSA encryption is 7 and 29. Then the RSA encryption process convert the original text into CD)a. If RSA encryption run several times with same key value to the string ABCDEF then every time same type of cipher which is CD)a will be produced. In several encryption process, symmetric public key is used. As a result when a text is passed through the encryption process with several times then same cipher text is produced. When same message or text is send from one side to other side with such kind of encryption technique then every time same kind of cipher text is send. Similar type of cipher is benefitted for side channel attack. The possibility to get the original message from several types of similar cipher is very high because there is no different calculation for same type of cipher. For such type of security violation we proposed a randomly generated asymmetric key. If consider the previous string ABCDEF for encryption process for proposed algorithm then first time corresponding cipher text will be (..’A.’T.’g.’Z.’//’. Second time the ciphertext-2 for ABCDEF will be )vo./1.F1.]1.t1.-2 with the proposed encryption technique which is different from first ciphertext-2. If several times the string ABCDEF is gone through the proposed encryption technique then every time different type of cipher is produced. Different type of cipher is produced because of randomly generated key. Randomly generated key value is highly secure for data encryption and decryption process. If third party somehow manage the cipher and try to discover the original message then possibility to get the original message is very low. The third party collected cipher is different from one another. The calculation for different cipher is not same which cause headache for third party. The proposed algorithm is designed in such a way that generated various cipher for same string with randomly generated key. For that the corresponding cipher provided much more security. B. Security Comparison The conventional and the proposed encryption system have significant differences in encryption method, key type and key exposition possibility. The given table 1 focuses these differences and proves the strength of the proposed algorithm.

R ESULTS AND A NALYSIS

This section analyzes the performance of the proposed approach through the appropiate setup to secure the multimedia data in the cloud server. The different size of multimedia data takes different time to generate different ciphertext-1 and then ciphertext-2. The comparative analysis shows that the performance of this setup. The algorithm gives hopeful result to secure multimedia contents tested in various formats and sizes.

C. Encryption and Decryption Time Analysis This section depicts several graphs and represents encryption and decryption time for different formats and size of images, audios and videos. The related multimedia data are discussed in details in the below different subsection. Three types of multimedia contents in various sizes are given in the Table 2. The data sizes are measured in the Mega Byte (MB) unit. The execution time measured in second and

TABLE I.

S ECURITY C OMPARISON WITH C ONVENTIONAL A LGORITHM

1.5 Encryption Decryption 1.25

Conventional Encryption System Singular symmetric key Fixed High

Encryption Method Key Type Key exposition possibility

Proposed Encryption System Double symmetric and asymmetric key Random Low

Execution Time (Sec)

Section

1

0.75

0.5

0.25

D IFFERENT TYPES OF DATA

Item No.

Image (MB)

Audio (MB)

Video (MB)

1 2 3 4 5 6 7 8 9 10

0.07 0.25 0.34 0.50 0.63 0.76 0.87 1.00 1.23 1.50

1.00 1.25 1.50 1.80 2.00 2.50 2.75 3.00 3.25 3.50

1.50 1.70 1.85 2.00 2.50 2.75 3.00 3.25 3.50 4.00

0

Fig. 6.

0

0.2

1.6

2.4

1.6

0.8

0

Fig. 7.

0.8

1.5

2.2 Data Size (MB)

2.9

3.6

Encryption and Decryption Time of MP3 Audio

Figure 7 and Figure 8 illustrates that the execution time for MP3 and WAV is similar to the small data size. With the increasing data rate, there is a little bit difference between them. RM has a lower execution time with great performance. 3) Video: Due to the large data size in the video the execution time of encryption and decryption is comparatively higher than the image and audio file. The execution time measured in minute though it was measured in second for the image and audio. Figure 9 and Figure 10 graphically represents the encryption and decryption time for the MPEG and MP4 videos respectively. Figure 9 exhibits that there is a small difference between the encryption and decryption time for MPEG video. In Figure 10 it shows that the encryption and decryption time for MP4 videos is almost same for the data size below 5 MB. The MP4 videos are taken 2.68 minutes to encrypt the 8MB data. It takes 2.43 minutes to decrypt for the same data size. 4

1.5

Encryption Decryption

Encryption Decryption 1.25

3.2 Execution Time (Sec)

Execution Time (Sec)

1.4

3.2

2) Audio: The Figure 7 and the Figure 8 depict the encryption and the decryption time for the MP3 and the WAV audio respectively through the graphical view. The MP3 file has a higher encryption time. The highest encryption time is 3.51 second for 3.5 MB MP3 file and 2.65 second for the WAV. The result for Adaptive Multi-Rate (AMR) and Real Media (RM) audio is almost same.

1

0.75

0.5

2.4

1.6

0.8

0.25

Fig. 5.

1.2

Encryption Decryption

1) Image: Figure 5, depicts the encryption and decryption time of the proposed algorithm for JPEG image. The maximum encryption time is 1.09 second for 1.5 MB image. The maximum decryption time is about 1.31 seconds of the graph. The encryption and decryption time is almost same for the data size below the 0.5 MB. The decryption time is smaller than the encryption time for the large data size. The encryption and decryption time of the algorithm for PNG image depicts in Figure 6 where the different data size of PNG and the execution time represent along the x-axis and the y-axis respectively. The maximum encryption and decryption time for 1.5 MB image are 1.101 seconds and 0.56 second respectively, though these times is almost same for the PNG below 0.65 MB. The encryption algorithm takes more times for the large data size.

0

0.6 0.8 1 Data Size (MB)

4

minute. The x-axis represents the item of different sizes of the multimedia content and the y-axis indicates the execution time. The red line and the blue line represent the encryption and the decryption time respectively.

0

0.4

Encryption and Decryption Time of PNG Image

Execution Time (Sec)

TABLE II.

0.2

0.4

0.6 0.8 1 Data Size (MB)

1.2

1.4

Encryption and Decryption Time of JPEG Image

0

1.6

Fig. 8.

0.8

1.5

2.2 Data Size (MB)

2.9

Encryption and Decryption Time of WAV Audio

3.6

4

[4]

Encryption Decryption

Execution Time (min)

3.2

2.4

[5]

1.6

[6] 0.8

0

Fig. 9.

[7] 1.5

2.5

3.5 4.5 5.5 Data Size (MB)

6.5

7.5

8.5

[8]

Encryption and Decryption Time of MPEG Video

[9]

4 Encryption Decryption

[10]

Execution Time (min)

3.2

2.4

[11] 1.6

0.8

0

Fig. 10.

[12] 1.5

2.5

3.5 4.5 5.5 Data Size (MB)

6.5

7.5

8.5

[13]

Encryption and Decryption Time of MP4 Video [14]

Several graphs depicted earlier represent encryption and decryption time of the multimedia contents. The algorithm is convenient to secure multimedia contents in the cloud for its randomly generated asymmetric encryption key. VI.

[15] [16]

C ONCLUSION

This paper represents a double stage encryption algorithm that provides the security of multimedia contents such as image, audio and video in the cloud. The proposed algorithm is crucial in the second stage. The randomly generated key provides more security than the conventional encryption system. The 94-bit converter generates the multimedia contents into the ciphertext. The ciphertext is stored in the cloud instead of original multimedia content. The cipher text is undoubtedly hard to recover the original content for it’s random asymmetric key. Wide application of the proposed algorithm protect the information from the side channel attacker to grab the multimedia data into the cloud. Thus, the multimedia content is safe in the cloud. In Future, it would be interesting to provide security of the adaptive HTTP video in mobile cloud computing using Software Defined Networking (SDN). R EFERENCES W. Kim, “Cloud Computing: Today and Tomorrow.” Journal of object technology, vol. 8, no. 1, pp. 65–72, 2009. [2] H. Takabi, J. B. Joshi, and G.-J. Ahn, “Security and Privacy Challenges in Cloud Computing Environments,” IEEE Security & Privacy, no. 6, pp. 24–31, 2010. [3] S. Marston, Z. Li, S. Bandyopadhyay, J. Zhang, and A. Ghalsasi, “Cloud computingthe business perspective,” Decision support systems, vol. 51, no. 1, pp. 176–189, 2011.

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