APPLICATION TO MANAGEMENT OF MEDICAL IMAGES BACKUP USING MOBILE DEVICES BY SSH TUNNELING

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1 APPLICATION TO MANAGEMENT OF MEDICAL IMAGES BACKUP USING MOBILE DEVICES BY SSH TUNNELING Felipe Rodrigues Martinêz Basile 1, Flávio Cezar Amate 1,2 1 Núcleo de Pesquisas Tecnológicas, Mogi das Cruzes University, Mogi das Cruzes, Brazil 2 Instituto Federal de Educação, Ciência e Tecnologia de São Paulo, Bragança Paulista, Brazil Abstract: Considering the growing use of mobile devices on health area, we can observe that studies are necessary about viability of use of these new techologies to transmission of medical images over secure and reliable network environment. Because of this we purpose the development of software using shell script language to transmission of medical images, using mobile devices, attending security rules defined by national and international regulations. Through implementation of rsync linux command, SSH-2 tunneling, private and public keys on android and linux environment. In the comparison of transmission using different RSA cryptographic keys (1024 and 4096 bits), there isn't significant statistical difference using Student's t tests (p>0.05) in the performance considering total time and rate transmision in all 30 experiments. Finally, we can demonstrate the viability of transmission of medical images using mobile device to backup of medical information between two medical images servers considering performance, confiability and security. Keywords: Hospital Information Systems, Medical Informatics, Network Communication Protocols, Telemedicine. Resumo: Diante da crescente utilização de dispositivos móveis na área da saúde, observa-se a necessidade de estudos relacionados a viabilidade do emprego dessas novas tecnologias, para a transmissão de imagens médicas em um ambiente seguro e confiável. Por isso propomos o desenvolvimento de um software em linguagem shell script para transmissão de imagens médicas, utilizando-se dispositivos móveis, atendendo normas nacionais e internacionais em telemedicina, por meio da implementação do comando rsync, de um túnel criptografado com o protocolo SSH-2 e de chaves públicas e privadas em ambiente linux e android. Em todos os 30 experimentos não houve diferença estatística significativa (p>0.05) utilizando Teste t Student na comparação de desempenho utilizando chaves criptográficas com algoritmo RSA (1024 e 4096 bits), considerando tempo total gasto e taxa de transferência. Desse modo demonstrou-se a viabilidade da utilização de dispositivos móveis para a cópia de informações médicas entre dois servidores considerando desempenho, confiabilidade e segurança. Palavras-chave: Sistemas de Informação em Hospitais, Informática Médica, Redes de Comunicação de Computadores, Telemedicina. Introduction The process of digitalization of medical images become possible the archivment and transmission of these images by different computer systems¹. Hospitals and medical centers use hardware and software through PACS (Picture Archivment Communication Systems) to integrity patients information including exams and electronic health records². Considering the evolution of technology, we can observe the growing use of mobile devices on health area. At the same time that occur the development of mobile society, where there will the use of mobile devices with wireless network at the telemedicine³. In this context, the telemedicine can be employed on different areas as: electric engineering, computer science, biomedical engineering and medicine 4. Studies are necessary to promote the development of hospital information systems to understand new ways about transmission of medical information, helping health professionals to easy access of clinical records and fast transmission of medical images on real time 5,6. 1

2 In the transmission of medical information is very important maintainment of secret and confidentially, once time there are much information that can't be revealed as (HIV result tests, the use of drugs and alcohol and psych records 7 ). On January 15, 2009, the brazil federal council of medicine established resolutions 8 that regulate the main aspects to the transmission of electronic medical information at the country. This resolution was based on Tel Aviv Declaration (1999) 9 considering important points as: the establishment of an apropriated infra-structure where can be possible implements confidentially, private and professional secret aspects in the transmission of medical information. Studies were developed to analyze the viability of transmission of medical images using the process of SSH (Secure Shell) tunneling to cryptography of all information between remote computers using the SSH protocol version Comparing the performance between computers on different networks using HTTP (HyperText Transfer Protocol) and SSH protocols in the transmission of medical images over the internet. Moreover studies demonstrate the implementation of security aspects using SSH protocol version 2 with private and public keys to applied of secure authentication 10,11. Another important study was made about the development of an open source software based on Java and Shell script language implemented to linux environment to transmission of medical images using SSH tunneling 12. For this reason, studies are very necessary to understand new techniques about the transmission of medical information and development of hospital information systems to telemedicine services. Using different network communication protocols and attending national and international resolutions on telemedicine. Applying the use of mobile technologies to maintainment and update of computer services, and transmission of medical information between servers machine using SSH protocol, considering important aspects of computer communications as: performance, confiability and security 13. Methods Software Development Process First, we used the software development process to create our program to transmission of medical images. In the software development process is recommend some fundamental steps 14. Requirements (functional and non-functional), analyze and project, implementation and tests. Functional requirements are defined as: copy images and access server, as well as, non-functional requirements as: linux operating system, SSH protocol version 2, shell script language, wireless and local network, mobile device, indeed the external android application called ConnectBot. After this step, we made the analyze of requirements defining main software functionalities. As result of this, we built a software project based on functional requirements and development of use case context diagram that demonstrates functionalities of software without internal aspects by high level of comprehension. (See Figure 1) Figure 1: Use case context diagram 2

3 On the implementation step we wrote a shell script language inside linux operating system using text editor called Vim to write the source code. The command rsync was implemented with SSH-2 tunneling to run copy of images between two servers machines (See Figure 2). Figure 2: Rsync command implemented over SSH protocol version 2 After implementation steps, we did some functionalities tests called as black box tests. These tests verified software funcionalities without worried about internal aspects related to source code application 15. In view of that we created a script to running functional tests considering the use of rsync command (See Figure 3). Figure 3: Script to run functional test Experiments Second, we did some experiments considering the implementation of hardware architecture with the following materials: one tablet pc and two computers inside of WLAN (Wireless Local Area Network)(See Figure 4). The mobile device used on experiments was Tablet PC (Motorola Xoom) with the following characteristics : 1 GBytes of RAM memory, Hard Disk with 32 GBytes of capacity, dual-core processor technology, android operating system (Ice Cream Sandwich 4.0). The computer 1 (Medical Image Server A) has 2 GBytes of RAM memory, single-core processor technology (AMD Athlon 64 Processor 3000+) with linux operating system (Ubuntu Lucid bits). Together with the computer 2 (Medical Image Server B) which has 512 MBytes of RAM memory, Hard Disk with 20 GBytes, pentium 4 processor with 1.90 GHz, with linux operating system (Ubuntu Precise Pangolin LTS). Figure 4: Hardware Implementation Diagram Public and private keys was created based on concepts of SSH-2 protocol to authentication process between mobile device and medical images server A, likewise between medical images server A and medical images server B. 3

4 These keys were created using RSA cryptographic algorithm with 1024 bits and 4096 bits. These two keys with diferent values of bits was created to verify if the increase of bits number on key can will modify performance aspects on transmission of medical images between machines. Another important point of use of these keys is related to the authentication process without manual password typing, considering a secure authentication in communication between devices. The Android application connectbot 16 was used to establishment of a remote connection between mobile device and medical server A. This application allowed a secure remote connection by the implementation of SSH-2 tunneling, together with configuration of sshd_config file changing deafult number of communication port to improve security. The Figure 5 has a screen of mobile device that contain linux terminal of medical image server A. Figure 5: Screen of mobile device that contain linux terminal of medical images server A. Immediately, we used the software developed based on shell scripts language to transmission of medical images from server A to server B, using rsync command implemented over SSH protocol version 2. Results We did 60 experiments considering transmission of medical images by SSH-2 tunneling between two medical images servers with MB of data sent and received. We used the RSA cryptographic key with 1024 bits in 30 experiments and RSA cryptographic key with 4096 bits in others 30 experiments. In an effort to compare performance, observing the total time (s) and transmission rates (Mbytes/s) with different sizes of cryptographic keys. In accordance with statistical analyzes there isn't significative difference using Student's test t (p>0.05) when we compared average transmission rates using crypotographic key with 1024 bits with cryptographic key with 4096 bits and in the same way in the comparison of total time spent on transmissions. In the Table 1 is the comparative table related to performance using different cryptographic keys based on RSA algorithm. Table 1: Performance of transmissions with different cryptographic keys Cryptographic Algorithm Average Total time (s) Average transmission rates (MB/s) RSA 1024 bits RSA 4096 bits

5 Discussion The high level of security was established by SSH-2 tunneling with RSA cryptographic key of 4096 bits compared with another RSA crytographic key with 1024 bits. And results show that the increase of security by strong key didn't change the performance of transmission between machines on wireless local area network. Equally important we implemented the use of mobile devices to access medical image servers on telemedicine 3,4. We did all experiments following international and national regulations about appropriated infra-structure to transmission of electronic health information 8,9. And at the same time we applied secure concepts on development of software as: profissional secret and confidentially 7 by implementation of SSH-2 tunneling 10,11,12 used on experiments. Conclusion A new software based on software development process with SSH-2 tunneling using high level of security with strong RSA cryptographic keys of 4096 bits, and the use of rsync linux command can demonstrate the viability of transmission of medical images using mobile device, on android environment, to backup of medical information between two medical images servers considering performance, confiability and security. Acknowledgements The authors thank to FAEP (Fundação de Amparo a Pesquisa) and CAPES (Coordenação de Aperfeiçoamento de Pessoal e Nível Superior) by all financial support. References [1] Aach, T.; Schiebel, U.; Spekowius, G. Digital image acquisition and processing in medical x-ray imaging. Journal of Electronic Imaging.1999;8(1):7-22. [2] Armbrust, L. J. PACS and Image Storage. Veterinary Clinics of North America-Small Animal Practice. 2009;39(4): [3] Varshney, U. Pervasive healthcare and wireless health monitoring. Mobile Networks & Applications. 2007;12(2-3): [4] Lin, C-F. Mobile Telemedicine: A Survey Study. Journal of Medical Systems p [5] Liu, BJ, Zhou Z, Gutierrez, MA, Documet J, Chan L, HUANG, H. K. International Internet2 connectivity and performance in medical imaging applications: Bridging the Americas to Asia. Journal of High Speed Networks 2007;16(1): p [6] Ohashi K, Sakamoto N, Watanabe M, Mizushima H, Tanaka H. Development of a telediagnosis endoscopy system over secure Internet. Methods of Information in Medicine 2008; 47(2): [7] Kobayashi LOM, Furuie SS. Segurança em informações médicas: visão introdutória e panorama atual. Revista Brasileira de Engenharia Biomédica 2007;23(1): [8] Conselho Federal de Medicina - CFM. Define e Normatiza a Telerradiologia. Resolução n. 1890, de 15 de janeiro de Diário Oficial da União nº 12-19/01/2009 (Segunda-feira) - Seção 1 - Pág. 94. [9] Assembléia Geral da Associação Médica Mundial. Declaração de Tel Aviv. Sobre Responsabilidades e normas éticas na utilização da Telemedicina Tel Aviv, Israel. 5

6 [10] Basile FRM, Amate FC. Viability of Secure Transmission of medical images by SSH tunneling in the computer network. In: 4th IADIS International Conference e-society, Avila, Spain March [11] Basile FRM, Amate FC, Secure Transmission of medical images by SSH Tunneling. Proceedings in the Communications in Computer and Information Science (CCIS), 9-14 July 2011, Florida, USA. [12] Basile, F R M, Amate, FC. Open Source Application to secure transmission of medical images. In: V Congresso Latino Americano de Ingenería Biomédica, Havana, Cuba Mayo [13] Forouzan BA. Comunicação de dados e redes de computadores. 4a ed. São Paulo: McGraw-Hill; p.7. [14] Bezerra E. Visão Geral. Modelagem de Sistemas de Software. Princípios de Análise de Sistemas com UML. Rio de Janeiro: Campus; [15] Myers GJ, Wiley & Sons J. The Art of Software Testing, 2, Nova Jersey: [16] Root K, Sharkey J. ConnectBot Available at: Access on 02 march Contacts Author: Felipe Rodrigues Martinêz Basile. [email protected] Author: Flávio Cezar Amate [email protected] 6