Department of Computer Science | Institute of Systems Architecture | Chair of Computer Networks
Today's forecast: cloudy with some rain Towards secure & reliable Cloud Computing
Dr.-Ing. Stephan Groß
DESY Computing Seminar Hamburg, 16 January 2012
Faculty of Computer Science Chair for Computer Networks
26 professors 2300 students
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9 post-docs 31 total staff and PhD candidates
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Research Topics Applications Peer-to-Peer Internet
Devices
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Access Technologies
Large-Scale Computing
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Flexible Service Architectures for Cloud Computing
Mobile and Ubiquitous Computing Internet Information Retrieval
Real-Time Collaboration Energy Lab
Network Planing and Security
Service & Cloud Computing
EU-funded research group: 10/2010 – 9/2013
Dr.-Ing. Josef Spillner Dipl.-Medieninf. Marc Mosch Dr.-Ing. Stephan Groß Dipl.-Medieninf. Yvonne Thoß Dr.-Ing. Anja Strunk
Exploring Cyber Physical Systems
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Outline
Cloud Computing
• What is it all about? • Problems? • π-Box: Building your personal secure cloud • Secure Cloud Storage • Conclusion & Future Work
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The shape of a cloud …
… is in the eye of the beholder.
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Definition
Cloud Computing is …
On-demand self service
Rapid elasticity
… the on-demand and pay-per-use application of virtualised IT services over the Internet.
Broadband network access
Measured service Resource pooling Adopted from the NIST Definition of Cloud Computing [MeGr2011]
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• What is it all about? • Problems? • π-Box: Building your personal secure cloud • Secure Cloud Storage • Conclusion & Future Work
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FlexCloud Objectives
Unified Cloud Prevent Vendor-Lock-in + Integration of existing IT Secure Cloud Ensure data privacy and security Managed Cloud Keep the user in command Efficient Cloud Adapt to user preferences and cloud's vital signs
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FlexCloud research topics
Cloud Adaption and Optimization Strategies for the compensation of SLA violations Strategies for minimisation of energy consumption Mechanisms for the visualisation of comples Cloud Monitoring data
Cloud Surveillance and Incident Detection Specification of monitoring targets and SLA violations Models for the proactive recognition of SLA violations and the evaluation of Cloud‘s energy efficiency Mechanisms for reliable distributed Monitoring DESY Computing Seminar, 2012/01/16
Fine-grained Service Level Agreements Methods to determine fine-grained nonfunctional properties of Cloud Services Identification of assets and corresponding requirements Deduction of monitoring targets from SLAs
Dynamic Provider Selection and Cloud Setup Flexible distribution mechanisms for Cloud Platforms Strategies for the performance optimization of Cloud Applications Reputation consideration to improve reliability and trustworthiness
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• What is it all about? • Problems? • π -Box: Building your personal secure cloud • Secure Cloud Storage • Conclusion & Future Work
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FlexCloud's approach
Subsume all end devices within a Personal Secure Cloud (π-Cloud) controlled by the π-Box.
π-Cloud
π-Box
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FlexCloud's approach
π-Box distinguishes between public and sensitive data and enforces security mechanisms for the later.
π-Cloud
π-Box
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Transparent encryption
Analysis of structured, unstructured data and context information π-Cloud
PKI PKI
??
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Building a cloud of clouds
… by connecting several π-Clouds. Propagation of data and services within one π-Cloud and to others.
π-Cloud
π-Box
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π-Box architecture User Interface / GUI
Service execution wrt. to security and other non-functional requirements.
Virtualisation
Service Service Controller Controller
Data Data Controller Controller
Data storage & distribution wrt. to security and other non-functional requirements.
Infrastructure management Resource ResourceManager Manager Peer2Peer Network
private resources (trustworthy) DESY Computing Seminar, 2012/01/16
public resources (not necessarily trustworthy) # 16
π-Box deployment models
π-Box
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• What is it all about? • Problems? • π-Box: Building your personal secure cloud • Secure Cloud Storage • Conclusion & Future Work
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Increasing availability: From RAID to RAIC RAIC: Redundant Array of Independent Clouds RAID: Redundant Array of Independent Disks
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Secure Cloud Storage Integrator for Enterprises (SecCSIE) System Architecture [SGS11]
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Uploading files (1/5)
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Shared Folder
• • • •
Technology: FUSE (Filesystem in Userspace) CIFS/SMB network share on proxy file server Unified user interface for arbitrary cloud storage services Utilizing CIFS access control mechanisms
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Uploading files (2/5)
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File dispersion
k n
E.g. k=6, n=8 Ensure availability despite of unreliable cloud storage provides. DESY Computing Seminar, 2012/01/16
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Secret Sharing aka Threshold schemes Objective:
Divide a secret s2S in n pieces s1,…,sn with
1. Knowledge of any k or more si pieces makes s easily computable. 2. Knowledge of any k-1 or fewer si pieces leave s completely undetermined (in the sense that all its possible values are equally likely).
Sharing Input: s
Dealer
Share holders
… s1
Share holders store
Reconstruction
s1
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s2
s2
si1
sn …
si2
sik Reconstructor
sn
Output: s*
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Secret Sharing: An informal example
[Source: http://goo.gl/watJC]
Visual Cryptography
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[NaSh1994]
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Secret Sharing: More formalism
e r u c e ! s ic ent t e ci r o ffi e th e e n c o a i t sp a Shamir's scheme m ot r Idea: It takes k points n a polynomial of degree k-1. o to define f t Sharing: Be a :=s2S In where buS is an infinite field.
Source: Wikipedia
Blakley's scheme [Blakley1979] Idea: Any n nonparallel n-dimensional hyper-planes intersect at a specific point. Sharing: Encode the secret as any single coordinate of the point of intersection. Recovering: 1. Calculating the planes' point of intersection. 2. Take a specified coordinate of that intersection.
[Shamir1979]
0
Randomly choose (k-1) coefficients a1,a2,…ak-12S to build f(x):=ÆaiÁxi. Calculate shares sj:=[j,f(j)] mit j2ℕn. Recovering: Use Lagrange interpolation to find coefficients of the polynomial including constant term a0. DESY Computing Seminar, 2012/01/16
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Information Dispersal: Computationally secure secret sharing Rabin's scheme [Rabin1989] • Be ai:=s2S where i=1,…k. Rest as with Shamir's secret sharing. • With a polynomial and shares of the same size as before, we can now share a value k times as long as before. • Length of each share is only 1/k-th of the length of the secret, and if k shares must be sufficient for reconstruction, one can obviously not get shorter. ➔ Space optimal • However, one might gain some information if he gets access to several shares ➔ Computationally secure • More efficient codes: – Need to be maximum distance separable to use k arbitrary shares for reconstruction – Examples: Cauchy-Reed-Solomon, Liberation, Blaum-Roth [PSS2008] DESY Computing Seminar, 2012/01/16
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Uploading files (3/5)
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Cryptography: Confidentiality & Integrity
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AES-CBC
+ SHA256
AES-CBC
+ SHA256
AES-CBC
+ SHA256
AES-CBC
+ SHA256
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Uploading files (4/5)
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Uploading files (5/5)
Met a
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dat
a
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Downloading files (1/3)
X X
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Downloading files (2/3)
X X
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Downloading files (3/3)
Met a
X dat
a
X
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Prototype implementations
SecCSIE: [SGS11]
NubiSave:[SBM+11] DESY Computing Seminar, 2012/01/16
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Cloud Computing
• What is it all about? • Problems? • π-Box: Building your personal secure cloud • Secure Cloud Storage • Conclusion & Future Work
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Results so far & Future work • Integration of existing cloud storage services (Cloud-of-Clouds) • Proxy server for transparent mediation ➔ easy to use for end-user ➔ common scheme for enterprises • High security and data sovereignty for the user • Good performance but space for improvement • • • •
Collaboration scenarios, file sharing, access by external entities Securing the meta data database Automatic classification of data Improving performance, e.g. scheduling algorithms, Caching/Prefetching, parallelisation • Data store for database system
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Tomorrow's forecast: still cloudy with sunny spots Contact:
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[email protected] http://flexcloud.eu/
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References & Credits References [Blakley1979]
G. R. Blakley: Safeguarding cryptographic keys; AFIPS Conference Proceedings Vol. 48, National Computer Conference (NCC) 1979, 313-317.
[MeGr2011]
P. Mell and T. Grace: The NIST Definition of Cloud Computing. NIST Special Publication 800-145, September 2011.
[NaSh1994]
M. Naor and A. Shamir, Visual Cryptography , Eurocrypt 94.
[PSS2008]
J. S. Plank, S. Simmerman, C. D. Schuman: Jerasure: A Library in C/C++ Facilitating Erasure Coding for Storage Applications – Version 1.2. Technical Report CS-08-627, University of Tennessee, 2008.
[Rabin1989]
M. O. Rabin: Efficient Dispersal of Information for Security, Load Balancing, and Fault Tolerance; Journal of the ACM 36/2 (1989) 335-348.
[SBM+2011]
J. Spillner, G. Bombach, S. Matthischke, R. Tzschicholz, and A. Schill: Information Dispersion over Redundant Arrays of Optimal Cloud Storage for Desktop Users. In: IEEE International Conference on Utility and Cloud Computing. Melbourne, Australien, December 2011.
[SGS2011]
R. Seiger, S. Groß, and A. Schill: A Secure Cloud Storage Integrator for Enterprises. In: International Workshop on Clouds for Enterprises. Luxemburg, September 2011.
[Shamir1979]
A. Shamir: How to Share a Secret; Communications of the ACM 22/11 (1979) 612613.
Credits Kudos to Ronny Seiger and Josef Spillner, both for providing slides and contributing to the research work. Furthermore, I would like to thank Marc Mosch for the best styled graphics.
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