1. A secure and traceable E-DRM system based on mobile device
Source: Expert Systems with Applications,
Vol. 35, No. 3, pp , 2008
Authors: Chin-Ling Chen
Reporter: Ya-Chieh Huang
Date: /3/19

2. Outline Introduction The proposed mobile E-DRM scheme Analyses
Package Phase
Register Phase
Authorization Phase
Analyses
Conclusions

3. Introduction(1/2) Author Mobile User (MU) Package Server (PS)
Content Server (CS)
License Server (LS)

4. Introduction(2/2)
The file structure of the mobile E-DRM system

5. Notations Parameter Usage The timestamp The time constant
The digital certificate
The ith one time password
The initial random seed number
The ith request random number, N0 = SEED
The DRM format digital content
International Mobile Equipment Identification
The content identity
The authorization request message of the mobile user
The symmetric key is used to encrypt/decrypt the digital content
Use X’s public/ secrete key to sign a message m
Two collision free one way hash functions

6. Package Phase (1/4)
The author creates the digital content and then sends it to the PS. PS CS
Packs the digital content (M)
Generates KEYCID
Generates the content header (CH)
Integrates C and CH into the mobile E-DRM format file

7. Package Phase (2/4) PS CS Stores the mobile E-DRM format file

8. Package Phase (3/4) PS LS
Stores

9. Package Phase (4/4)
After connecting to the public directory of the CS MU
Downloads 1. the mobile E-DRM format file
2. the corresponding tamper resistant DRM-AP
Realizes the authorization authority URL

10. Register Phase DRM-AP AA LS Cert, IMEI Verifies Cert Generates SEED
Stores Cert, IEMI, and SEED
SEED
IEMI, Cert

11. Authorization Phase (1/3)
The tamper resistant DRM-AP tries to open the protected the digital content (the ith times)
DRM-AP AA
Generates
Checks
Verifies
Finds

12. Authorization Phase (2/3)
DRM-AP AA
Computes
Generates
Stores
Stores

13. Authorization Phase (3/3)
DRM-AP AA LS
Compares
with

14. Analyses Security issues No attacker can impersonate the legal party
Against replay attacker
Persistent protection issues
Integrity issues
Track usage of E-DRM work issues
Integration with existing applications issues
Portability issues

15. Conclusions
Portability
Security
Low computation cost