Abstract：A sensitive data protection method (SDPM) for web servers in the cloud was proposed to prevent sensitive data leakage from the compromised web servers, which utilizes the features of virtualization and combines the concepts of data encryption and execution isolation. By predetermining and fixing a small amount of application codes that will compute over sensitive data, and by encrypting sensitive data before these data are available to the rest of untrusted codes, the SDPM provides strong defense against all malicious codes that an attacker may run in the server software stack. The SDPM was implemented based on the kernel of Xen Hypervisor and PHP. The results show that the amount of sensitive codes is small with a percentage of less than 2% and the overhead of protecting sensitive data is moderate with a percentage of less than 40% according to six popular web applications in this paper.
韩心慧, 王东祺, 陈兆丰, 张慧琳. 云端Web服务器敏感数据保护方法研究[J]. 清华大学学报（自然科学版）, 2016, 56(1): 51-57,65.
HAN Xinhui, WANG Dongqi, CHEN Zhaofeng, ZHANG Huilin. Method for sensitive data protection of web servers in the cloud. Journal of Tsinghua University(Science and Technology), 2016, 56(1): 51-57,65.
 The OWASP Foundation. Top 10 2013-A6-Sensitive Data Exposure[EB/OL]. (2013-02).https://www.owasp.org/index.php/Top_10_2013-A6-Sensitive_Data_Exposure.
 Verizon. 2013 Data Breach Investigations Report[EB/OL]. (2013). http://www.verizonenterprise.com/resources/reports/rp_data-breach-investigations-report-2013_en_xg.pdf.
 Popa R A, Redfield C, Zeldovich N, et al. Cryptdb: Protecting confidentiality with encrypted query processing [C]//Proceedings of the 23rd ACM Symposium on Operating Systems Principles. New York, NY: ACM Press, 2011: 85-100.
 Puttaswamy K P N, Kruegel C, Zhao B Y. Silverline: Toward data confidentiality in storage-intensive cloud applications [C]//Proceedings of the 2nd ACM Symposium on Cloud Computing. New York, NY: ACM Press, 2011: 10.
 Parno B, McCune J M, Wendlandt D, et al. CLAMP: Practical prevention of large-scale data leaks [C]//Security and Privacy, 2009 30th IEEE Symposium on. Piscataway, NJ: IEEE Press, 2009: 154-169.
 Felt A P, Finifter M, Weinberger J, et al. Diesel: Applying privilege separation to database access [C]//Proceedings of the 6th ACM Symposium on Information, Computer and Communications Security. New York: ACM Press, 2011: 416-422.
 Lampson B, Abadi M, Burrows M, et al. Authentication in distributed systems: Theory and practice [J]. ACM Transactions on Computer Systems (TOCS), 1992, 10(4): 265-310.
 Wikipedia. Trusted computing base [EB/OL]. (2002-02).http://en.wikipedia.org/wiki/Trusted_computing_base.
 Howard M. Attack surface: Mitigate security risks by minimizing the code you expose to untrusted users [EB/OL]. (2004-11). http://msdn.microsoft.com/en-us/magazine/cc163882.aspx.
 McCune J M, Parno B J, Perrig A, et al. Flicker: An execution infrastructure for TCB minimization [J]. ACM SIGOPS Operating Systems Review, 2008, 42(4): 315-328.
 Dworkin M. Recommendation for block cipher modes of operation: Galois/counter mode (GCM) and GMAC [R]. Gaithersburg: US Department of Commerce, National Institute of Standards and Technology, 2007.
 McGrew D, Viega J. The Galois/counter mode of operation (GCM) [EB/OL]. (2004).http://siswg.net/docs/gcm_ spec.pdf.
 Wikipedia. Block cipher mode of operation [EB/OL]. (2014-05). http://en.wikipedia.org/wiki/Block_cipher_mode_ of_operation.
 Gueron S, Kounavis M E. Intel? carry-less multiplication instruction and its usage for computing the GCM mode, Intel white paper [R]. 2012.
 W3Techs. Usage of server-side programming languages for websites [EB/OL]. (2014-04). http://w3techs.com/technologies/overview/programming_language/all.
 Gueron S. AES-GCM for efficient authenticated encryption: Ending the reign of HMAC-SHA-1? [C]//Workshop on Real-World Cryptography. Stanford: Stanford Univ, 2013.
 The PHP Group. vld Package Information [EB/OL]. (2003-09).http://pecl.php.net/package/vld.
 Crawljax. Crawling Ajax-based Web Applications [EB/OL]. (2007-10). http://crawljax.com.
 Computer Science Department at the University of Illinois at Urbana-Champaign. The LLVM Compiler Infrastructure [EB/OL]. (2002-06). http://llvm.org.