©2010 International Journal of Computer Applications (0975 - 8887)
Volume 1 – No. 19 DNA bad Cryptography: An Approach to Secure
Mobile Networks
Harneet Singh Computer Science & Engineering Deptt Thapar University,
Patiala
Karan Chugh
Computer Science &
Engineering Deptt
Thapar University,
Patiala
Harsh Dhaka
Computer Science &
Engineering Deptt
Thapar University,
Patiala
A. K. Verma
Computer Science &
Engineering Deptt
Thapar University,
Patiala
ABSTRACT
Security has always been the main concern in data communication and networking. Mobile Netwo
rks are highly vulnerable to curity attacks and po a great challenge for the wireless networks being ud today. Since the mode of communication is open, the networks do not carry any inherent curity and hence are prone to attacks. The prent day algorithms have shown limitations to meet the curity requirements of transmission. DNA cryptography is a new and promising direction in the field of cryptography. This paper propos DNA-bad Cryptography as an approach to ensure highly cure environment for transmission of data across mobile networks.
Categories and Subject Descriptors
D.4.6 [Security and Protection]: Cryptographic Controls General Terms
Algorithms and Security
Keywords
Mobile Networks, DNA Cryptography, Security
1.INTRODUCTION
The era of Personal Computers is changing to an era of Ubiquitous Computing. Wireless net
works have succeeded as they provide a better solution for interconnection of ubiquitous devices [1][7]. Mobile networks, characterized by anytime, anywhere communication [9]; the next generation of wireless communication systems, are an autonomous system of mobile routers and associated hosts that are connected by wireless links. The approaches applied in wired networks cannot be ud for mobile networks due to vast differences in the characteristics of both the networks in terms of cost, power consumption and computational abilities [8][5]. Since the communication takes place in the open air, lack of centralized monitoring and management point, the networks are prone to attacks. Security in a network bad on cryptography provides veral aspects such as confidentiality, integrity, authenticity and non repudiation [3]. DNA cryptography is bad on central dogmas of molecular biology [1]. However, pudo DNA cryptography is different from actual DNA cryptography. The propod method does not u biological DNA quences (or oligos) or the quences generated in-vitro, but only the DNA terminology and mechanisms of DNA function [2][6]. The cipher and decipher process are bad on the concepts of DNA transcription, splicing and RNA translation [2].
The structure of the paper is organized as: Section 2 reviews the related concepts, Section 3 describes the propod methodology of using DNA bad Cryptography. Section 4 discuss analysis drawn from the findings and Section 5 concludes the paper. 2.RELATED WORK
Mobile Networks are wireless, open, temporarily meshed networks compod of a group of mobile nodes. Each node acts as a router and forwards packets to other nodes to reach destination [8]. As no fixed infrastructure is required for their establishment, they are highly lf-organizing. Mobile networks are characterized by feature of having distributed approach, dynamic topography and peer to peer analogies. Various proactive routing protocols like Open Shortest Path First (OSPF), Destination Sequenced Distance Vector (DSDV) and on-demand protocols like Ad hoc On-demand Distance Vector (AODV) and Hybrid routing protocols like Zone Routing Protocol (ZRP) are available which assume collaboration between nodes so they lack any embedded curity mechanism and hence are more prone to curity attacks [5]. The attacks can either be active attacks or passive attacks. Active attacks harm the network resources such as denial of rvice and modify the information being transferred. On the contrary, passive attacks without harming the network resources acquire the information and u it for unauthorized purpos such as releasing the message contents [4].
Modern day cryptography includes the process of encryption and decryption along with the involvement of various distinct mechanisms such as symmetric or asymmetric key encipherment and hashing [4]. In symmetric cryptography, both the encryption and decryption keys are same and need
to be exchanged between the nder and receiver beforehand. Asymmetric cryptosystems u different keys for encryption and decryption; the encryption key is public and decryption key is retained by its owner. The propod cryptographic algorithm follows symmetric cryptographic scheme.
3.PROPOSED ALGORITHM
The following pudo code provides an insight into the methodology ud. The nder node converts the original message into cipher text using the following steps:
BEGIN
Step 1: Select the message, M, to be nt, and convert into an 8 bit Extended ASCII code, M bin.
Step 2: Convert M bin into DNA notation, say M dna using the following convention: A=00, T=01, G=10, C=11 where
A, T, G, C are DNA ba pairs. The M dna, as per
analogy, compris of exons and introns.
Step 3: Select the pattern to be spliced (introns), say S from Ф(M dna) where Ф(M dna) is the function that determines
the random pattern to be spliced. The message becomes
M*dna such that M*dna= M dna–nS, where n is the
number of the times the pattern appears in the M dna.
// M*dna compris of exons only and forms m-RNA quence which is ud for protein synthesis.
Step 4: The positions from where the pattern is spliced, the spliced pattern and the position of splicing are added to
the key file, K1.
Step 5: Compute the length of M*dna, say l(M*dna).
Step 6: Set Flag= l(M*dna) mod 3.
CASE I: If flag= 0 then
i. Convert M*dna into amino acid quence M amino using
Ө(M*dna) that combine 3 bas (codon) in M*dna to
form an equivalent amino acid using genetic code
table.
CASE II: If flag= 1 then
i.Compute the complementary ba to the last ba in
the M*dna using C(M*dna) where C(M*dna) computes
the complementary ba to the last ba in M*dna .
ii. Append the complementary bas at the end of M*dna twice. Let new message be M*dna= M*dna +
C(M*dna) + C(M*dna) .
iii.Convert M*dna into amino acid quence M amino using Ө(M*dna) that combines 3 bas (codon) in
M*dna to form an equivalent amino acid using
genetic code table.
CASE III: If flag= 2 then
i. Compute the complementary ba to the last ba in
the M*dna using C(M*dna) where C(M*dna) computes
the complementary ba to the last ba in M*dna..
ii. Append the complementary ba at the end of M*dna once. Let new message be M*dna= M*dna + C(M*dna).
iii.Convert M*dna into amino acid quence M amino using Ө(M*dna) that combines 3 bas (codon) in M*dna to
form an equivalent amino acid using genetic code
table.
Step 7: The mapping details from codon to amino acid and the flag value are added to the key file, K2.
END
The above methodology can be summarized as shown in Figure 1 below:
Figure 1: The Communication Process
The receiver obtains the original message from the cipher text and keys using the following procedure:
BEGIN
Step 1: The message M amino is converted into M*dna using the (ӨR, K2) where ӨR is the rever of Өsuch that M*dna
= ӨR (M amino).
Step 2:Using the value of Flag cut the appended bas from M*dna .
Step 3: M*dna compris only of exons and process of Rever splicing (ФR, K1) such that M dna= ФR (M*dna).
Step 4: The message is converted into binary, M bin form from DNA notation.
Step 5:M bin is in Extended ASCII with respect to original message which is converted back using rever
convention.
END
4.FINDINGS AND ANALYSIS
Suppo the DNA form of data M dna hav e the length …m‟. Let there be …i‟ introns and the average length of introns be …l‟. So
the length of the data after the introns are spliced from the DNA would be m-i*l. Since one codon consists of 3 bas so the length of the protein form of data would be (m-i*l)/3.
It is found that the nder needs to traver the complete data once for splicing the introns from the DNA. So the time complexity of the splicing process is O(m). For translation, the
M*dna is traverd only once leading to complexity O(m). Hence,
the total time complexity of the encryption process is O(m). At
the receiving end, the cipher text is traverd once each for both
the keys to obtain the plaintext in linear time with a total time complexity of O(m).
It is analyzed that if some malicious node captures the data during the transfer between the nodes, it can only get cipher text. The probability of obtaining plaintext from the cipher text is very low even if brute force method is applied. To obtain M*dna from M amino, 20 amino acids are to be mapped to 61 codons, thereby leading to 3 possibilities for every amino acid on an average. So, there would be 3(m-i*l)/3 total possible combinations to obtain the correct M*dna. Now to obtain M dna there are (m-i*l)+1 possible places for the inrtion of intron. Every time an intron is inrted, the number of possible places for the inrtion of intron also increas by 1. Since there are i introns, so the total combinations for rever splicing are (i*(2(m-i*l)+i+1)/2), which is of the order O(m). As the number of introns and their length decreas, the time complexity of rever splicing will decrea but the time complexity of rever translation will increa. Hence, the total possible combinations for the decryption using brute force are (3(m-i*l)/3*3*i*(2(m-i*l)+i+1)/2), which is of order O(3m), thus requiring very large computational time to decipher the plaintext. Also, the dynamic nature of nodes does not allow brute force attacks to become successful due to large number of possible permutations. Further the brute force attacks fail in this scenario becau the pattern that is to be spliced off varies with the plaintext.
The simulations are performed by using C++ Developers compiler on Windows Vista (Home Edition) system. The hardware configuration of the machine ud is Core2duo processor/ 2 GB RAM/ 4 MB cache. The results of simulation have been summarized in Table1 and Table 2.
Table 1 shows the performance of propod algorithm with different ts of plaintext varying in context and length.
Table2 shows the performance of the propod algorithm on different ts of data, highly diver in nature covering wide range of Extended ASCII characters.
Table 1: The performance of application with different length of plaintext
Table 2: The performance of algorithm with plaintext of different context
The obrvations from the simulation have been plotted in Figure 2 and Figure 3 to carry out the length-time analysis and length analysis respectively.
Figure 2: Length Time Analysis
Figure 3: Length Analysis
From the Length-Time analysis as shown in Figure 2, it can be obrved that as the length of plaintext increas, the time for encryption and decryption also increas. The encryption time and decryption time are almost same at higher values of the length of plaintext.
From the Length analysis as shown in Figure 3, it is obrved that the length of cipher text is 20% m
ore than the plaintext and the length of the keys is 5.5 to 6.5 times the length of plaintext, incorporating sufficient amount of redundancy. However, the length of keys can be reduced by varying the style of splicing. One of the limitations of mobile networks is that they have limited computational abilities, so the implementation of our algorithm to ensure curity can be challenging. On the basis of findings and analysis, the algorithm is found to posss some limitations as follows: 1.During encryption process, there might not be enough introns
to be spliced off. A solution is for nder to prepare many starting and ending codes of introns, and lect a pair which can result in an appropriate cut off.
2.The complexity of decryption process increas as the size of
key increas.
3.Trust authority is required to verify the node entering the
Mobile Network.
5.CONCLUSION AND FUTURE WORK Mobile networks are gaining popularity in large community of people including the rearch scholars and business enterpris. The vulnerability of
mobile networks to attacks makes curity one of the major issues in data transmission. The propod algorithm is analyzed to be strong enough as the permutations required by a brute force attack are sufficiently high to decipher the message being nt across the mobile network. It can be concluded from the various analysis that the propod DNA-bad cryptosystem promis to be a better solution for implementation in curing the mobile networks. Further, this method can be incorporated as a hardware solution. However, the limited computational ability of the nodes in mobile networks is still an issue, which can be worked upon in future.
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