Evaluation of the effect of SSL overhead in the performance of e-business servers operating in B2B scenarios Daniel F. Garcı ´a a, * , Rodrigo Garcı ´a b , Joaquı ´n Entrialgo a , Javier Garcı ´a a , Manuel Garcı ´a a a Department of Computer Science and Engineering, University of Oviedo, Campus de Viesques, 33204 Gijon, Spain b Center for the Development of Information and Communications Technologies, Scientific Park, 33203 Gijon, Spain Available online 23 June 2007 Abstract In the current business to business environments, transactions between e-business servers must be carried out with a high security level. To carry out secure transactions, the servers must do additional tasks, such us exchanging encryption keys and encrypting and decrypting the information interchanged during the transactions. The combination of several specific algorithms for these tasks consti- tutes a cipher suite. The additional tasks degrade the server performance and the challenge is to quantify the degradation as a function of the cipher suite selected. Until now, several research works have evaluated the impact of security on the performance provided by web servers using static and very simple dynamic contents. However there is a lack of research into the impact of security on the performance of e-business servers which execute complex transactions, some of them involving additional transactions with other servers. This work presents an evaluation of the impact of using SSL, with several representative configurations, on the performance of e-busi- ness servers. The business application used to carry out this execution is the TPC-App benchmark, which is a good representation of business-to-business environments. The benchmark runs on a cluster of two layers. The results of this evaluation are unexpected, because the impact of SSL on performance is small compared to the results of previous works that evaluate web servers, for which the impact of SSL on performance is very high. Therefore, this work provides insight to solve the tradeoff between security and performance when an SSL cipher suite must be selected for a complex e-business system rather than for a simple web server. Ó 2007 Elsevier B.V. All rights reserved. Keywords: e-Business server performance; SSL overhead; B2B environments; Impact of security on performance; TPC-App benchmark 1. Introduction The main goal of an application server in a business-to- business (B2B) environment is to provide its services to the maximum number of concurrent business clients. Gener- ally, the interactions between e-business servers are always carried out within secure sessions commonly based on SSL (Secure Sockets Layer) connections [10,21]. The SSL proto- col was originally designed at Netscape for its web brows- ers and servers, but was later standardized by IETF and is now called TLS (Transport Layer Security) [9]. The SSL/ TSL protocol gives security to the HTTP transactions [16] using cryptographic techniques [19] that demand com- putational resources. Therefore the utilization of secure connections in business sessions between two or more machines would degrade the performance of an application server, that is, the throughput of the server would decrease and its response time would increase. In this paper, we evaluate the influence (overhead) of security on application server performance, analyzing the server behavior as a function of the number of concurrent e-business clients supported in two scenarios: with and without security. The experimental environment is based on our imple- mentation of the TPC App benchmark [20], which provides 0140-3664/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.comcom.2007.05.040 * Corresponding author. Present address: Department of Computer Science, office 1.2.14, Edf., Departmental Oeste, Campus de Viesques, 33204 Gijon, Spain. Tel.: +34 985 182 066; fax: +34 985 181 986. E-mail address: dfgarcia@uniovi.es (D.F. Garcı ´a). www.elsevier.com/locate/comcom Available online at www.sciencedirect.com Computer Communications 30 (2007) 3063–3074