FlexCloud: Reliable and Secure Cloud Overlay Infrastructures

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Department of Computer Science | Institute of Systems Architecture | Chair of Computer Networks

FlexCloud: Reliable and Secure

Cloud Overlay Infrastructures

2013

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Who we are

Dr.-Ing. Josef Spillner

Dipl.-Medieninf. Marc Mosch

Dr.-Ing. Stephan Groß

Dipl.-Medieninf. Yvonne Thoß

Dr.-Ing. Anja Strunk

(from left to right)

EU-funded research group

Network

Planning and

Security

Internet

Information

Retrieval

Mobile &

Ubiquitous

Computing

Real-Time

Collaboration

Energy

Lab

Service &

Cloud

Computing

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# 3

Cloud Computing …

•

What is it all about?

•

Problems

•

π

-Box: Building your personal secure cloud

•

π

-Data Controller: Secure Cloud Storage

•

Conclusion & Future Work

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The shape of a cloud …

… is in the eye of the beholder.

IaaS/PaaS* Cloud Operating System,

part of Azure Platform

PaaS*

Development and hosting of web applications

SaaS/PaaS*

IaaS* Migration of virtual machines between private

SaaS*

Customized applications for business and home user, based on Google App

Engine, e.g. collaboration tools

(5)

# 5

Cloud Computing Characteristics

Cloud Computing is …

… the

on-demand

and

pay-per-use

application of

virtualised

IT services

over the

Internet

.

On-demand self service Broadband network access Resource pooling Measured and optimized service Rapid elasticity

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Service & Deployment Models

Software Services (SaaS)

Platform Services (PaaS)

Infrastructure Services (IaaS)

User Interface Machine Interface

Components Services

Compute Network Storage

User/Clients pte d fr om [ M eG r2 0 1 1 ] an d [B K NT 2 0 1 0 ]

Cloud Architecture Stack

Public

Hy

brid

Private

Community

C

on

ve

n

ie

n

ce

User Control

Cloud Organization

Virtual Resource Set (VRS) Programming Environment

Execution Environment Applications Services

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# 7

Cloud Computing …

•

Problems

•

π

•

π

-Data Controller:

Secure Cloud Storage

(8)

Reliability and security when giving up physical possession

>

Failure of monocultures

>

Cloud providers‘ trustworthiness

>

Staying in control

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# 9

FlexCloud Objectives

π-Cloud: Establishing a secure cloud computing life cycle

Hybrid cloud platform to integrate a user’s (cloud) resources,

services and data.

> 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

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Cloud Computing …

•

Problems

•

π

•

π

-Data Controller: Secure Cloud Storage

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# 11

Subsume all end devices within a Personal Secure Cloud

(

π

-Cloud) controlled by the

π

-Box.

π

-Cloud

π-Box

(12)

π

-Box distinguishes between

public

and

sensitive

data

and enforces security mechanisms for the latter.

π

-Cloud

π-Box

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# 13

Analysis of structured,

unstructured data and

context information

PKI

π

-Cloud

?

Document classification concerning

security requirements.

Addressee identification and

derivation of respective keys.

(14)

Conceptual design of a user-centric cloud management solution

•

Categorization of user groups concerning technical skills and organizational interests

•

Guidelines for constructing adaptable graphical user interfaces

•

Refinement of user profiles according to individual preferences

Organization of a user’s cloud resources

•

Description of cloud resources and their (non-)functional properties

•

System architecture for a reliable and scalable cloud resource directory

•

Protocols for automatic (de-)registration of cloud resources within the π-Cloud

π

-B

o

x

π

-Service

Controller

π

-Data

π

-Resource Manager

π

-Cockpit

Peer-to-Peer Network

public resources

(not necessarily

User Interface / GUI

User-controlled reliable data storage in the cloud

•

Automatic assurance of availability, integrity and confidentiality

•

Easy integration of existing IT environments

•

Adaptable and optimizable storage with respect to user preferences

Service

execution with

respect to

security and

other

non-functional

requirements.

Data storage &

distribution with

respect to security

and other

non-functional

requirements.

Infrastructure

management

π

-Box Architecture

User-controlled reliable service execution in the cloud

•

Automatic composition and deployment of services with respect to security and other

non-functional properties

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# 15

Cloud Computing …

•

Problems?

•

π

•

π

-Data Controller: Secure Cloud Storage

(16)

Unreliable, proprietary and insecure cloud storage Unreliable, low quality hard disk

Increasing Availability: from RAID to RAIC

RAID:

Redundant Array of Independent Disks

Redundant Array of Independent Clouds

RAIC:

Integration Layer

Logical partition

Preprocessing Layer

RAID level redundancy routine (mirror, stripe, …)

Transport Layer Block resources Reliable, universal and secure cloud storage Integration Layer Versioning Distributed file system Web access Preprocessing Layer

Fragment level transformation (e.g. encryption) File level transformation

(e.g. compression) Dispersal routine

Transport Layer

Caching Local persistence Provider Storage API adapter

Reliable disk storage

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# 17 π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Secure Cloud Storage Integrator for

Enterprises (

System Architecture)

API FTP CIFS

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π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Storing Files (1/5)

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# 19

•

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

User space

Kernel

VFS

FUSE

NFS

Ext3

…

ls - /tmp/fuse ./xmp /tmp/fuse

glibc

libfuse

CIFS = Common Internet File System NFS = Network File System Ext3 = Third Extended File System SMB = Server Message Block FUSE = Filesystem in Userspace VFS = Virtual File System glibc = GNU C library

(20)

π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Storing Files (2/5)

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# 21

Ensure availability despite of

unreliable cloud storage providers …

n

total # of shares a file is split into

k

threshold, i.e. # of necessary shares to reconstruct

E.g. k=6, n=8

If k < n, we need

redundant information.

File Dispersion

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Objective:

Divide a secret

𝑠∈𝑆

in

𝑛𝑛

shares

𝑠↓𝑠↓𝑠↓111   , …, , …, , …, 𝑠↓𝑛 𝑠↓𝑛 𝑠↓𝑛 

with

1.

Knowledge of any

𝑘

or more

𝑠↓𝑖 𝑠↓𝑖 

shares makes

𝑠𝑠

easily computable.

2.

Knowledge of any

𝑘−1 or fewer 𝑠↓𝑖 

shares leave

𝑠

completely undetermined

(in the sense that all its possible values are equally likely).

Input:

𝑠

𝑠↓1  𝑠↓2  𝑠↓𝑛 

…

Dealer

Share holders

store

Sharing

…

Share holders

Reconstructor

Reconstruction

Output:

𝑠↑∗  s↓i↓1   𝑠↓𝑖↓2   s↓i↓k  

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# 23 [S ou rce : h ttp: // go o. gl /w atJ C ]

Secret Sharing:

An informal example with 2 shares

Visual Cryptography

[NaSh1994]

Simplification:

n = k = 2

Secret cannot be determined independently!

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Shamir's scheme

[Shamir1979]

Idea:

It takes

k

points to define a polynomial of degree

k-1

.

Sharing:

Be

a

₀

:=s

є

S

the secret to be shared where

S

is an

infinite field known to all share holders.

Randomly choose

(k-1)

coefficients

a

₁

,a

₂

,…a

_k-1

є

S

to

build

f(x):=

Σ

a

_i

·x

i

.

s2

Secret Sharing: More formalism

s m W iki pe di a.

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.

Example: n≥3, k=3 1 share available 2 shares available 3 shares available

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# 25

Information Dispersal:

Computationally secure secret sharing

Rabin's scheme

[Rabin1989]

• 

Guarantees only availability but no secrecy.

• 

Construction

Be

𝑎↓𝑖 

≔

𝑠

∈

𝑆

where

𝑖

=1, …,

𝑘

, i.e.

𝑓(𝑥)

≔

∑𝑖

=1

↑𝑘▒𝑠

∙

𝑥↑𝑖  

.

Rest as with Shamir's secret sharing.

• 

Properties

•

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 information dispersal schemes

• 

Need to be

maximum distance separable

to use

𝑘

arbitrary

shares

for reconstruction.

(26)

π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Storing Files (3/5)

(27)

# 27

+

SHA256

+

SHA256

+

SHA256

+

SHA256

AES-CBC

(28)

π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Storing Files (4/5)

(29)

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Storing Files (5/5)

Stored Meta Data per component

•

Shared Folder:

General file system information, e.g. file size, access rights …

•

File Dispersion:

Used dispersion algorithm/parameters (n, k), shares‘ locations

•

Cryptography:

Used cryptographic keys and calculated checksums per share

•

Cloud Storage

(30)

π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Retrieving Files (1/3)

Dispersion parameters:

n=6

(31)

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Retrieving Files (2/3)

Dispersion parameters:

n=6, k=3

(32)

π-Data Controller

π

-Cloud =

Company Intranet

Cloud

S

to

ra

ge

Pr

oto

co

l

A

da

pte

r

Shared

F

ol

de

r

Meta Data

Fi

le

D

ispe

rsi

on

C

ry

pto

gr

aph

y

Retrieving Files (3/3)

(33)

# 33

[SGS11] web interface for π-Cockpit

[SBM+_11]

π-Cockpit desktop application

ResUbic Cloud Storage Allocator for Cyber Physical Systems

(34)

Performance Evaluation Upload

Test case π-Box used # local storage # cloud storage # encrypted shares

1 No 0 1 0

2 Yes 0 1 0

3 Yes 8 0 0

4 Yes 4 4 4

(35)

# 35

Performance Evaluation Download

Towards User Centric Data Governance and Control in the Cloud

Test case π-Box used # local storage # cloud storage # encrypted shares

1 No 0 1 0

2 Yes 0 1 0

3 Yes 8 0 0

4 Yes 4 4 4

5 Yes 0 8 8

File size: 24 MB; Dispersion parameters: n=8, k=6;

Cryptography parameters: AES (256 bit, 14 iterations), SHA256;

(36)

π-Box

SOHO

Enterprise

π

-Box Scalability

Embedded systems

AVM FRITZ!OS plugin

Home Server

Enterprise Server

(37)

# 37

Cloud Computing …

•

Problems?

•

π

•

π

-Data Controller:

Secure Cloud Storage

(38)

Results so far & future work (

π

-Data Controller)

•

Integration of existing cloud storage services (Cloud-of-Clouds)

•

Proxy server for transparent mediation

➔

easy to use for end-user, common scheme for enterprises

•

Good performance, high security & data control for the user

•

Data store for database system (block-based dispersion)

•

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, parallelization

(39)

# 39

… by connecting several

π

-Clouds and propagating data and

services within one

π

-Cloud and to others.

Simplified approach:

assuming public, i.e.

insecure

π

-Clouds

Advanced approach:

Trust relationships

between

π

-Clouds

π-Box

π

-Cloud

(40)

Towards a secure cloud life cycle

Cloud Adaption and Optimization

Strategies for the compensation of SLA violations

Strategies for minimization of energy consumption

Mechanisms for the visuali- zation of complex Cloud Monitoring data

Fine-grained Service Level Agreements

Methods to determine fine-grained non- functional properties of Cloud Services

Identification of assets and corresponding requirements

Deduction of monitoring targets from SLAs

Cloud Surveillance

and Incident Detection

Specification of monitoring targets and SLA violations

Models for the proactive recognition of SLA violations and the evaluation of a

Dynamic Provider

Selection and Cloud Setup

Flexible distribution mechanisms for Cloud Platforms

Strategies for the performance optimization of Cloud Applications

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# 41

Tomorrow's forecast:

still cloudy but sunny spots

Contact:

[email protected]

http://flexcloud.eu/

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References

[BKNT2010] C. Baun, M. Kunze, J. Nimis and S. Tai: Cloud Computing. Web-basierte dynamische IT-Services. Springer Verlag, 2010.

[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) 612- 613.