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2nd International Science, Social Science, Engineering and Energy Conference 2010: Engineering Science and Management

Data Security Transmission via a Noisy Channel

K. Mitsophonsiria,*, S. Punthawanuntb, S. Mitathac and P.P. Yupapind

a,bFaculty of Science and Technology, Kasem Bundit University, Bangkok 10250, Thailand cHybrid Computing Research Laboratory, Faculty of Engineering

King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand dNanoscale Science and Engineering Research Alliance, Advanced Research Center for Photonics Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang Bangkok 10520, Thailand

Elsevier use only: Received 15 November 2010; revised 15 December 2010; accepted 20 December 2010

Abstract

We propose a novel method that can be used to perform the data verification and encryption by using the microring resonators incorporating an add/drop filter, where the confidentiality and integrity of information in optical communication can be formed. In this paper, the encryption is formed by the chaotic noise sophisticates irreversible and unpredictable in the nonlinear microring resonator. The proposed system is used to generate the message authentication code for maintaining data integrity, where the noisy signals are created by the microring resonator and combined with the encoded information to protect the man-in-the-middle attacks (decipher). By using the extremely small processing device, the proposed design can be easily applied to secure any form of communication in wireless network, mobile communication network and military applications with low power consumption and very high-speed procedures.

© 2010 Published by Elsevier Ltd.

Keywords: Data security, Communication security, Noisy channel, Optical communication

1. Introduction

Chaotic behavior has been studied in several areas in either theory or applications such as mathematics [1], physics [2], electronics [3], and communications [4]. The benefit of such a property is accepted, for instance, the chaotic communication has recently been attracted the great interest because of its potential applications in the use for secure and confidential communications, where it uses a noise-like broadband chaotic waveform as a communication carrier. Furthermore, the chaotic noise has been found useful in several areas of applications such as electronic communication [5], switching and control [6] and optical communication [7]. Where the present use of the benefit of such a nonlinear behavior, especially, in the military purpose for when the information is required to be kept confidential. In general, the nonlinearity of the system involves the behaviors such as chaos, bistability and bifurcation, which can be generated in the electronic circuit and optical fiber [8, 9], laser system [10] and optical waveguide [11]. One application is the use of the device known as a microring resonator, which can be formed by a

* Corresponding author. Tel.: +6-689-445-2224; fax: +6-627-227-262. E-mail address: khuanlux_mi@science.kbu.ac.th.

1877–7058 © 2011 Published by Elsevier Ltd.doi:10.1016/j.proeng.2011.03.088

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waveguide or a fiber optic which has shown a very promising application when the noisy signal is generated and multiplexed to the required information, where the information can be retrieved by the required users. Moreover, this technique becomes great interest when such a device is fabricated within the range of a micrometer scale [12, 13], and can be used incorporating a system such as a mobile telephone hand set, computing system, and telecommunication networks. The published works of the secure communication systems based on chaos in a micro ring resonator were proposed by references [14, 15]. In this paper, we use chaotic effect in microring resonator as hashing or encrypted modules in couple security models, message authentication code and symmetric key encryption.

signal from the RFID chip. It is embedded in the radio ticket, which is a genuine. In addition, it can be used to link in each field so quickly and can be applied to security purpose, which has photographs and names of the ticket owners [1, 2]. This paper presents the use of an intelligent ticket that can be used incorporating with the ordinary ticket, where in this case more digital data, especially, personal data that can be available for security applications. The use of the corporative functions such as GPS (Global Positioning System) data, seat positions and personal and identification data can be available, in which the crime prevention in the sports, especially, in the stadium can be realized [3-5].

2. Noisy Signal Generation

A simple device schematic diagram is as shown in Fig.1. When light from a monochromatic light source is launched into a ring resonator, the relation of input light field and output light field, which is shown in equation (1) that given by [16].

In addition, the optical fields Er1 and Er2 represent the right and left hands circulations in a ring resonator, correspondingly. This equation indicates that a ring resonator in the particular case is very similar to a Fabry-Perot cavity, which has an input and output mirror with a field reflectivity, 1-κ , and a fully reflecting mirror. Where no

and n2 are the linear and nonlinear refractive indices, and the coupling coefficient is κ Where

represents a roundtrip losses coefficient, and are the linear and nonlinear phases

that shift respectively; is the wave propagation number in the vacuum and γ is loss in medium.

Fig.1. A Schematic diagram of the micro ring resonator.

This nonlinear behavior of light traveling in a single ring resonator (SRR) is described by Yupapin et al [18]. Where the parameters of the system were fixed to be λ0 = 1.55 μm, n0 = 1.54, Aeff is the effective mode core area of the fiber, Aeff= 0.30 μm2, the waveguide ring resonator loss (α) is 0.02 dBmm-1. The fractional coupling intensity loss (γ) is 0.1, and R1 = 10 μm. The coupling coefficient of the device is fixed to be κ = 0.0225. The nonlinear refractive index n2 = 1.4-2.2 x 10-15 m2/W [10], and the 20,000 iterations of roundtrips inside the optical fiber ring was calculated by assuming that φL = 0 for simplicity. By using these configurations in previous research,

(1)

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bifurcation and chaotic signals are generated [17], which can be electronically formed by the digital codes [19] or use as hashing and encryption box in any cryptographic model as shown in next section.

3. Message Authentication Code

In cryptography, a message authentication code (MAC) is information that uses to authenticate the message. The objective of MAC is to ensure that two or more parties, who share the secret key, can communicate with the capacity to identify any modifications to the message in transportation. This prevents an attacker from modifying the message to gain undesirable outcome. MAC algorithm is achieved by accepting as input the message and secret key and producing a fixed size MAC code. The message and MAC code are transmitted to the receiver, who can then re-compute the MAC code and compare it against the MAC code that was transmitted. If they match, the message is almost definitely approved. Otherwise, the message is incorrect and should be ignored, or drop the transmission, as it is likely being tampered with, depending on the situation. The general operation schematic diagram of MAC is as shown in Fig 2.

Because MAC algorithm characteristics such as sophisticates, irreversible, and unpredictable are much like chaos in microring resonator, MAC algorithm module can be built by using a microring resonator. In this research, two microring resonators and one add/drop are combined together as shown in Fig 3(a) to generate message authentication code. By this structure, input signal and key signal permute in a microring resonator. Afterward, both unformulated signal of input and key combined together using add/drop to generate message authentication code that exclusively related to data and key signal.

Fig 2. Message authentication code diagram

Fig. 3. (a) MAC generator using microring resonator (b) Data signal (c) Key signal (d) MAC signal

In operation, a sine wave with amplitude 1MHz, 0.4 mW, 4mW average power data signal and 0.35 MHz, 1.4 mW and 4 mW average power key signal are input into the system as shown in Fig. 3(b) and 3(c), respectively, then propagate into each waveguide as shown in Fig 3(a). The signal center wavelength (Lambda) of both signals is 1.55 µm. Key signals and data signal are hashed by 10 µm microring resonator radii, R1 and R3, respectively. Coupling coefficient of hashed microrings, κ1 = κ4,, which is equal to 0.212, where the linear and nonlinear coefficients are 1.2 and 3.8 x 10-13 cm2/W respectively, the effective core area equal to 0.30 µm2. Both outputs from each microring are

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input into add/drop filter, R3, to produce MAC code, the add/drop ring resonator radius is 5 µm, the coupling coefficient of add/drop are κ2 and κ3, which are equal to 0.9 and 0.1, respectively, the ffractional coupler intensity loss of both side of microring are γ = 0.3. The waveguide ring resonator loss is α = 0.06 dBmm-1. The MAC code can be formed by using the proposed configuration, which is related to key signal as shown in Fig 3(d). Furthermore, the digital message authentication code is able to generate by using digitized technique in [17].

4. Encryption and Decryption

In secure communication, encryption is method to ensure that transmission data between sender and receiver still unrevealed. This prevents an attacker from tapping information, exploit, modify, or obtain undesirable outcome from communication channel. Encryption algorithms accomplish this by accepting as input the message and secret key and producing a cipher text that unable to interpret without correct secret key and encryption algorithm. These secret messages are transmitted to the other party, who can then decrypt the cipher text into original data by using decryption algorithm and same secret key. Otherwise, the cipher text is unable to decipher into original message. Because characteristic of encrypting algorithms are much like characteristic of chaos such as sophisticates, irreversible, and unpredictable, encryption method can be built by using microring resonator.

Fig 4. Symmetric key cryptography method

Fig 5. Encryption simulation result (a) Key signal (b) Data signal (c) Encrypted data (d) Received data

To secure transmission via noisy channel, chaos signals are generated by passing key signal into microring resonator and then compose with encoded data to generate cipher text. At the receiver, users who know secret key are able to both generate the same chaos pattern and filter chaos signal from cipher text signal to get encoded data. Subsequently, by using suitable decoder, original data signal are produced. Schematic of these methods are shown in Fig 4. In this process, suitable procedures of encoder and decoder module for continuous signal are differentiation and integration function, respectively, to maintain the chaotic pattern of encrypted data in communication channel. When pass through communication channel, data signal always scramble within noisy signal. Any sniffed data

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between communication links are unable to interpret without same key information, correct microring specification, and suitable encoding method. This technique always maintains confidentiality along the transmission channel.

In our simulation, to generate hash signal, a sine wave with 0.25 MHz, 0.05mW amplitude, 4 mW average power key signal as shown in Fig 5(a), is input into a waveguide of 10 µm microring resonator radius. In addition, 1 W, 0.25 MHz sine wave with 4 W average power data signal as shown in Fig 5(b), is input into the encoder, where the encoded signal can be formed. The wavelength (Lambda) of waveguide is 1.55 µm, the coupling coefficient is equal to 0.212. The linear and nonlinear coefficients are equal to 1.2 and 3.8 x 10-13 cm2/W, respectively, the effective core area is equal to 0.30 µm2. Both encoded and chaotic signals are combined to produce the encrypted signal as shown in Fig 5(c). At the receiver end, both similar key signals and device configuration are required to generate same chaotic signal for decipher, where the cipher text and encoded data signal can be provided. Finally, the encoded data into decoding module to retrieve the original data is provided, as shown in Fig 5(d).

5. Image Steganography in Noisy Channel

Generally, the steganography is a security technique to hide information within other data for specific purposes, for instance, for owner identification, integrity inspection, or data verification. To conceal image into noisy channel, image information must be encoded into proper structure for enclosing with noisy signals. Both noisy signals and encoded image are combined together and transfer to the receiver. Outcome signals are also used in other purposes such as scramble other information, random number generation, message authentication code, or encryption. Along the communication channel, noisy signal protects the information by using their fuzzy pattern that is hard to identifying message information. All attackers who tapping the information recognizes only noise in communication link. At the receiver side, chaotic signals are extracted by the similar noise pattern, which is generated by using the similar secret key and equivalent microring resonator configuration, to obtain the encoded image. Afterward, decoder is used to reform the remaining data and release the hiding image.

In our simulation, the following configurations are used in the experiment. A sine wave with 0.25 MHz, 0.05mW amplitude, 4 mW average power key signal, as shown in Fig 5(a), is input into waveguide of 10 µm microring resonator to generate noisy channel. The waveguide wavelength is 1.55 µm, the coupling coefficient is equal to 0.212. Linear and nonlinear coefficients are 1.2 and 3.8 x 10-13 cm2/W, respectively. The effective core area is equal to 0.30 µm2. 8-bits-gray-scale Lenna image with 250x250 pixels encodes into bit stream of Return-to-Zero signals and coupling with noisy signal, which is generated by passing key signal into microring resonator. Then, noisy signals with image steganography are transferred into the communication channel. At the receiver side, both similar key signals and system configuration are used to generate same noisy signal for translate the signal and obtain encoded data. Then, launch the encoded data into decoding module to find original image. The result of our simulation, Lena image at sender, in the communication link and receiver, are illustrated in Fig 6.

Fig 6. Image steganography in noisy channel

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6. Conclusion

We have shown that message authentication code, secure channel, and image steganography in optical communication can be implemented by using the microring resonators incorporating an add/drop filter. The operation is shown the successful results by using chaos phenomenon in a microring resonator as hashing and encryption function in cryptography mathematics. In this model, any transmitted data and key pass into the optical hashing circuit to generate message authentication code that uses to validate integrity of transmitted data and its owner. Furthermore, by using microring and key signal to generate noisy channel, data sending from sender is secured in the transmission and also decipher at the receiver side. Encryption and decryption technique is able to use in steganographic process. The key advantages of the proposed system are simple to implement in single chip and easily apply to secure any form of communication in wireless network, mobile communication network and military applications with low power consumption and very high-speed procedures.

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