ITU-T Kaleidoscope Conference
Innovations in NGN
A Self-Encryption Based
Private Storage System over P2P
Distributed File Sharing Infrastructure
Hiroki Endo
The University of Tokyo
endo@akg.t.u-tokyo.ac.jp
Geneva, 12-13 May 2008
Outline
Introduction
Security for the lost of the terminal
Proposal
Self-encryption scheme
Distributed Storage System by Selfencryption
Problems
1.
2.
Large cost for processing for encryption
Large cost for Uploading data cR
Conclusion
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
2
Introduction
The number of the loss of articles（Tokyo, 2007)
12,810,340
400
350
About
1 % of people lost their mobile handsets
300
250
200
124,863
150
100
thousands
50
0
Umbrella
Clothes
Wallet
Securities Certificates
Mobile
Handsets
Bags
Camera &
Glasses
Precious
metals
Watches
Tokyo Metropolitan Police Department
http://www.keishicho.metro.tokyo.jp/toukei/kaikei/kaikei.htm
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
3
Purpose
Mobile handsets are lost easily!
Security for the case of loss
Encryption of all internal data of mobile handsets
For cases of the loss and theft
With Limited terminal resources
Computational resource
Communication resource
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
4
Outline
Introduction
Security for the lost of the terminal
Proposal
Self-encryption scheme
Distributed Storage System by Selfencryption
Problems
1.
2.
Large cost for processing for encryption
Large cost for Uploading data cR
Conclusion
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
5
Proposal
Self-encryption scheme
The encryption key is generated from the
information contained in the target file itself
according to a certain algorithm
This scheme outputs some distributed data
encrypted with generated keys
To decrypt the original file, all distributed data is required
Right Low cost processing
Wrong Long encryption key
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
6
Self-encryption Scheme
Sprit M into s pieces of data
Generate s encryption keys from these data by
Function F
Encrypt s data using these keys
M
m2
m1
m3
ms
F
Ek
s
ks
c1
k1
Ek
k2
1
Ek
F
c2
2
k3
k3
F
c3
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
s-1
F
Cs-1
Fs
Ek
cs
7
Key Generation Function
Our proposed scrambling algorithm
Generate key (K) from key source (Y)
Y
n byte
IV
y1
y2
y3
⊕
⊕
⊕
k1
k2
k3
yj
⊕
F
kj
K
⊕: exclusive OR, IV: initial value
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
8
Distributed Storage by Self-encryption scheme
An encrypted part of file (cR) is stored in
Remote storage
In cases of the loss and theft, the access to
Remote storage is blocked
This system is effective even if the mobile
handset is out of service!
Local Storage
cR
cL
Remote Storage
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
M
SD
SIM
9
Outline
Introduction
Security for the lost of the terminal
Proposal
Self-encryption scheme
Distributed Storage System by Self-encryption
Problems
1.
2.
Large cost for processing for encryption
Large cost for Uploading data cR
Conclusion
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
10
Problem Definitions
An encrypted part of file (cR) is stored in network storage
In cases of the loss and theft, the access to Network
storage is limited
Mobile Terminal
cL
cR
Remote Server
mR
M
mL
SD
SIM
Problems
1. Large cost for processing for encryption mL & mR
2. Large cost for Uploading data cR
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
11
Target Environment
Distributed Storage System Based on IMS framework
Communications are secure
Mobile terminals and Servers are authenticated
IMS Clients
mL
mR
: Remote Data
mL
: Local Data
Home
Server
MRFC
mR
S-CSCF
Access NW
MRFP
Visited NW
P-CSCF
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
I-CSCF
Home NW
IP NW
12
Problem 1
Cost for processing for encryption mL & mR
2
Processing Time [s]
1.8
y = 0.0011x
1.6
AES
1.4
Self-Encryption
> 1/3
1.2
1
0.8
y = 0.0003x
0.6
0.4
0.2
0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Encrypted Data Size [KB]
Experimental circumstance
Zaurus SL-C760，OS: Linux (OpenPDA)，
CPU: Intel XScale(PXA255 400MHz)，Work area: 64MB
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
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Answer 1 (1/2)
Mobile terminal transmits remote data to the
server in plaintext through secure pass
The remote server encrypts the remote data
stored in the network storage
Mobile Terminal
cL
mR
Remote Server
M
mL
SD
SIM
However, if the server is attacked, mR is leaked out
Distribute mR against attacks!!
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
14
Answer 1 (2/2) against server attacks
P2P Overlay Network Storage
Compose network storage of remote servers managed by
each user by P2P overlay NW (DHT).
Encrypt mR into s pieces of decryption data (cR1, cR2,…,cRs)
in his own server (Server A: Trusted Node[TN])
s pieces of decryption data are uploaded into Foreign Nodes
owned by other users (Foreign Node[FN])
Server B
(FN)
cR2
cR1
Server C
(FN)
User C
cR1
DHT NW
cR2
cRs
Server D
Geneva, 12-13 May 2008
(FN)
cRs
First ITU-T Kaleidoscope Conference – Innovations in NGN
mR
Server A
(TN)
User A
cL
15
Problem 2
To Reduce cost for Uploading remote
data mR
Mobile Terminal
cL
mR
Remote Server
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
M
mL
SD
SIM
16
Answer 2 (1/3)
There is large number of common files shared
among the users such as music tracks, movie videos
and novels .
Every file are encrypted into same cR
Sharing common cR with other users
If cR exists in the network storage, uploading cR is omitted,
the processing cost will be reduced
User B
User A
User E
User B
User D
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
17
Answer 2 (2/3)
P2P Overlay Network Storage
The trusted node decides which servers in a P2P
network manages each distributed data according
DHT ID
DHT ID is derived from only cL
Server B
(FN)
cR1
Server C
(FN)
mR
User Z
cL
Server Z
cR2
mR
cRs
Server D
(FN)
Geneva, 12-13 May 2008
Server A
DHT NW
First ITU-T Kaleidoscope Conference – Innovations in NGN
User A
cL
18
Ans. 2 (3/3) - The method for deriving DHT IDs
Mobile Terminal names mR “Hash:Size” derived from CL.
TN receives the name and derives DHT IDs consisting of the
name of mR, the distributing number and the ID of the
trusted node
If the data does not exist on DHT network storage, TN
receives mR and encrypts It and divide it s items (CR1 to CRs)
TN stores these s items to the corresponding nodes.
1.
2.
3.
4.
Mobile Terminal
mR
cL
Trusted Node
mR
3
1
Hash
Hash
TN
Hash
2
Hash
2
cR1
Size
1
cR2
Hash
Size
Size
2
s
cRs
Hash Size
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations ins NGNTN
FN D
FN A
Size
1
1
Size
4
cR1
TN
FN B
TN
cR2
FN F
Hash
FN Z
Size
2
TN
FN E
cRs
Hash
Size
s
TN
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For the Standardization
Require the following protocols
Authentication of mobile terminals and
servers
Mobile terminals are authenticated by IP
Multimedia Services Identity Module (ISIM)
Servers are authenticated by Public Key
Infrastructure (PKI)
The algorithms in self-encryption scheme
and protocols for communication
The method for deriving DHT IDs
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
20
Conclusion
A Self-encryption based private storage
system over p2p distributed file sharing
Infrastructure
Protect all internal data for cases of loss of the
terminal
Reduce costs for encryption processing in mobile
terminal
Reduce costs for upload processing by letting
users share common remote data.
P2P Overlay Network Storage
Protect servers against attacks.
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
21
Thank you for your attention!
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
22