Chip-Secured Data Access: Confidential Data on Untrusted Serves

1. KEEP OUT Chip-Secured Data Access: Confidential Data on Untrusted Serves Shetal Patel CSE 6331 – Spatial Database University of Texas at Arlington October 12, 2004 L. Bouganim, P. Pucheral, “Chip-Secured Data Access: Confidential Data on Untrusted Servers”, Int. Conf. on Very Large Data Bases, 2002. University of Versailles – PRISM Laboratory, France

2. Outline 1. Introduction 2. Data Confidentiality Problem 3. C-SDA Baseline 4. Query Management 5. Confidentiality & Encryption 6. C-SDA Scenario 7a. Future Work 7b. Conclusion 7c. References

3. Introduction • Why do we need security? (web, network, database) • Background • what is user authentication? • what is encryption/decryption? • what is symmetric/asymmetric? • what is SSL? • What is Smartcard?

4. Need for Security • Computing industry has moved from mainframe era to client/server era to Internet era • Web provide convenient, cheap, and fast way of publishing data • Corporate database are made more and more accessible to authorized employees over the internet • Customer information is maintain online for the needs of e-commerce and e-business application (.Net) • Amount of sensitive information collected and shared in marketplace is enormous - Confidentiality major concern

5. Need for Open Trusted Data Stores • Virtual teams • distributed among space, time and organizations • collaborative work on confidential data • Shared personal folders • accessible anywhere, anytime and shared by authorized persons • Corporate DB hosted by a DSP • Permanent access to traveling salesmen

6. Background • What is User Identification and Authentication? • What is encryption/decryption? • What is symmetric/asymmetric? • What is SSL? • What is smartcard?

7. Security Mechanisms • Symmetric / Secret Key Techniques • Same key to encrypt & decrypt message. • DES - 56 bit key considered unsafe for financial purposes since 1998. • Advantage • It is 100 to10,000 times faster then public key because it often use smaller key, perhaps even a user-password. • Disadvantage • the key must be securely exchanged between A & B. • if the key is compromised, the entire communication is instantly readable.

8. Security Mechanisms … • Asymmetric / Public Key Techniques • Keys come in pairs -- a public key known to all and a private (or secret) key known only by the user. • A message encrypted with the public key can be decrypted only by the private key & vice versa. • Public key are stored in public servers, usually in a X.509 certificate. • Advantage • as the private key is never shared, the system is secure. • Disadvantage • Slower then Secret Key technique because its usually 512 or 1024 bits long, which is about 50 to 100 character long.

9. Security Mechanisms Protocols • Secure Sockets Layer (SSL) protocol • SSL encrypts all data transmitted between a client and server during a session. • Protocol ensure confidential communication technique which is used by all major website. • Addresses to SSL secure page use the prefix “https” instead of common “http”.

10. What is Smartcard? • A plastic card with inbuilt silicon chip, which contained.. • micro-processor, system software, application software, permanent data engraved into non-volatile memory, some (less expensive) volatile memory • Most common smartcard Application • Credit cards, Electronic cash, Computer security systems, Wireless communication, Loyalty systems (like frequent flyer points), Banking, Satellite TV, Government ID… • Advantage • greater security, more storage capacity, standalone unit • Disadvantage • cost of installing new device or adapting existing terminal, external device (card reader)

11. 2. Data Confidentiality Problem 2.1 Definition - Data Confidentiality, Data Privacy 2.2 Different types of attackers 2.3 Database Security 2.4 Server-based approach 2.5 Data confidentiality requirement 2.6 Client-based approach 2.7 Data confidentiality problem

12. 2.1 Definition: Data Confidentiality, Data Privacy • Data Confidentiality • Ability to share sensitive data among users while respecting the privileges granted by the data owner to each member • Data Privacy • Data owned by an individual will never be disclosed to anyone else

13. 2.2 Attackers • Intruder • tries to attack the DB footprint or usurp the identity of a regular user (or DBA) • Insider • tries to get information exceeding her own access rights • Administrator (SA or DBA) • has enough privileges to tamper the access right definition and spy the DBMS behavior • Access rights can be bypassed • Encryption is required

14. 2.3 Database Security • User identification & Authentication • login/password, smartcard or biometric • Network encryption • guarantees confidentiality and the integrity of client/server communication • Server-enforced access control and privilege management • Can we trust server or web-hosting company? • Increasing hacking commercial or institutional site.

15. 2.4 Server-based approach • Server responsible for query execution, access right management, encryption and decryption of data • Data decrypted on fly by server at query evaluation time • DBA privileges make easier to change encryption package, get cryptographic keys, modify access rights and even snoop memory to get data while it is decrypted • Separate DBA (administering the db resources) and SA (administering user privileges, encryption keys and other security issues. Weakness = decryption occurs on the server

16. 2.5 Data Confidentiality Requirement • Confidential data must be managed by an auto-administered DBMS to cast off the DBA privileges • DBMS must be hosted by an auto-administered computing system to cast off the system administrator privileges • Computing system must constitute a Secure Operating Environment (SOE) to cast off any Intruder action

17. 2.6 Client-based approach • Decryption on the client • Who owns the keys? • Privacy (exclusive access) • Client manages the keys • Efficiency is the main concern • Confidentiality • A security mechanism is required on the client side to manage keys and access rights Weakness = client can tamper the security mechanism

18. 2.6 Client-based approach… • Benefits of using smartcard • secure and cheap • existing smartcard application dose not require any administration once downloaded on the card • hardware architecture makes tampering difficult, probably best SOE • high cost of attack and if tampered only the data of single user is revealed • Problem – lack of extensibility • Dynamic declaration of data and user access rights –user Weakness = client can tamper the security mechanism

19. 2.7 Data Confidentiality Problem • Confidentiality enforcement • Data confidentiality must be guaranteed against Intruder & DBA. Server-based solution not suitable – DBA privileges. • Storage capacity • System must not limit the volume nor the cardinality of the DB. Client-based solution not suitable – whole DB hosted on secured device. • Sharing capacity • Any data, may be shared among multiple authorize user. Client-based solution not suitable – data sharing is not supported. • Query capacity • Any data, may be queried through predicate-based lang. (typically SQL). This precludes solutions restricted to encrypted backups. • Pertinence • System must guarantee an acceptable response time to each user, must be scalable and must be economically visible to meet requirements of large public applications.

20. 3. C-SDA baseline 3.1 What is C-SDA ? 3.2 C-SDA Functional Architecture 3.3 Security Breach 3.4 Data Confidentiality Problem – Smartcard

21. 3.1 What is C-SDA? • C-SDA is to insulate data encryption, query evaluation and access right management in SOE • Making the Security mechanism tamper–resistant • Access right management hosted by Secure Operating Environment (SOE) (e.g. smartcard) • Access right defined on views • Query translation in SOE • Part of query execution in the SOE

22. C-SDA is a client based security component acting as an incorruptible mediator between a client and the encrypted database. This cooperation of hardware and software security allows the orthogonally between access-right management and data encryption to be reestablished. 3.2 C-SDA Functional Architecture

23. 3.3 Security Breach

24. Question – C-SDA (Figure 3) Q. Can we assume from the preceding discussion that a server acting as an encrypted repository for a smart card DBMS can integrate the smart card’s sphere of security (i.e. while keeping the level of confidence unchanged)? A. No. Since the server is not hosted by SOE. Typically, an Intruder may conduct destructive or deny of service attacks on the server. However, privacy and confidentiality are preserved thanks to encryption.

25. Question – C-SDA (Figure 3)… Q. Since data flows from the server to the smartcard DBMS is encrypted, can we infer that the communication channel is part of the smartcard’s security? A. No. communication channel may undergo several forms of attacks. Insider may compare the encrypted data issued from the server with query result that appears in plain text on its terminal.

26. 3.4 Data Confidentiality Problem – Smart Card • Confidentiality enforcement • Enforced by the fact that the smart card is a SOE hosting data and DBMS engine which is self or user administered. • Storage capacity • Limited by smartcard stable storage capacity. • Sharing capacity • Limited by the need to share physically the same card. • Query capacity • Query capacity limited to simple selection in SCQL standard. • PicoDBMS allows powerful query engines supporting selection, join, grouping and aggregate calculus • Pertinence • Performance – smartcard DBMS is mono-user and works on reduced set of data. • Scalability – one smartcard per user. • Price – few dollar per smartcard.

27. 4. Query Management 4.1 Smartcard Characteristics 4.2 Query Evaluation Principle

28. 4.1 Smartcard Characteristics • Cheap and highly secured computer • Powerful 32 bits RISC processor ( 35 MIPS) • Limited communication bandwidth (10 to 100 Kbps) • Tiny RAM, writes EEPROM stable storage very costly • Impact on C-SDA • Internal processing must be done in pipeline • Processing must be pushed down to the server • Data flow must be minimized

29. 4.1 Smartcard Characteristics.. • Limitation • Very limited storage capacity • Communication bandwidth (10 to 100 Kbps) • Very slow write time in EEPROM • Extremely reduced size of RAM • Benefits • High Security level • Powerful CPU with respect to other resources • Future Development • Augmenting the CPU power to increase the speed of cipher algorithms • Augmenting the capacity of the stable storage • Augmenting the communication bandwidth between chip an the card-reader

30. 4.2 Query Evaluation Principle • Split Query Q into a composition form • Server subquery (Qs) • Predicate based equality comparator {=,≠} • Smartcard subquery (Qc) • Inequi-predicates comparator {>,≥,<,≤} • Terminal subquery (Qt) • Confidentiality issues - handle the sort and distinct operators

31. 5. Confidentiality and Encryption 5.1 Database Encryption 5.2 Sensitive Data 5.3 Access Right Management 5.4 C-SDA: Limitation of Solution

32. 5.1 Database Encryption • Key insulation rule • encryption keys must remain confined in the smartcard • Sharing rule • encryption must remain orthogonal to access rights • Computation rule • encryption must preserve attribute equality comparisons • Performance rule • encryption must be symmetric and client-based • Multi-key encryption rule • encryption must exploit as much different keys as possible

33. 5.2 Sensitive Data • Highly sensitive data stored on smartcard (e.g., name, SSN, birth date, …) • Issues • how to integrate this sensitive data in the query evaluation process? • how to guarantee its durability? • how to share if it is used by multiple user? • Solution • Group sensitive data in sensitive domains and store indices referencing these domain values in place of corresponding data in server. • Benefits • Database and sensitive domains are located on two separate server thereby increasing the complexity of attacks. • Backup copy of the domain dose not need to participate in query evaluation.

34. Question – C-SDA (Figure 3)… Q. What kind of complexity do you see in enforcing sensitive data durability? Q. How can we create backup of static or dynamic domain? A. Static – duplicate on any secure storage device (e.g., backup smartcard) Dynamic domains – trickier to manage, if they are shared among multiple users. Solution: leave encrypted copy of the domain on a backup server and to synchronize this encrypted backup with the domain copy residing on smartcard at each connection.

35. 5.3 Access Right Management • Smartcard manages access rights and views • Definitions have to be securely stored in a server accessible by all smartcards Q. Who is responsible for granting/revoking access rights? A. Owner of the object inherits this responsibility. • C-SDA – DBA conserves all privileges to administer the database server but has no way to break the data confidentiality, as long as he/she wont have access to the user’s smartcard. Thus C-SDA user is unique holder of his data and can distribute among others.

36. 5.4 C-SDA: Limitation of Solution Q. What do u think is the limitation of this C-SDA solution? A. 1) Intruder can infiltrate user’s terminal in order to snoop the query results that are presented in plain text or alter query expression sent by the terminal to the smartcard before processing. 2) Intruder or Admin. may try to tamper DB footprint on disk in the hope of decrypting unauthorized data. This can be resolved by adding checksum attribute in each tuple.

37. 6. C-SDA Scenario 6.1 Query Execution with C-SDA 6.2a Optimization Issues 6.2b Optimization Issues – GUI (2003)

38. 6.1 Query Execution with C-SDA • Consider business DB application where Invoice department is willing to bill invoice having a total amount greater than $1000. • Assumed Invoice dept. clerk privilege is restricted to select operation on view Invoice. It prevents an untrusted clerk to access confidential order-lines.

39. 6.1 Query Execution with C-SDA… • Metadata refreshing • Access Right checking and view resolution • Query Splitting • Qstransmission and execution • QsResult transmission • Qc execution • Rc delivering and Qt execution

40. 6.2a Optimization Issues • Performance Problem • Assume only 1% of order satisfies the selection on date, 99% of Rs are irrelevant, generating bottle-neck on the smartcard input-channel. • Objective • Evaluate inequi-predicate on a data set smaller than Rs • Solution

41. 6.2b Optimization Issues – GUI (2003)

42. 7a Future Work • Performance assessment • Experiment in the EDI context • founded by the French ANVAR agency • extends C-SDA towards XML database • Study the impact of SOE technology on query optimization

43. 7b Conclusion • Introduction • Encryption, Symmetric, Asymmetric, SSL • Data Confidentiality Problem • Attacker • Server-based Approach • Client-based Approach • How C-SDA solve DCP? • C-SDA Query Management • Confidentiality and Encryption on sensitive data • C-SDA limitation to the solution • Query Execution & Optimization • Conclude with Future work

44. 7c References • Luc Bouganim, François Dang Ngoc, Philippe Pucheral, Lilan Wu, "Chip-Secured Data Access: Reconciling Access Rights with Data Encryption". Demo session, VLDB 2003, Berlin • Anciaux N., Bobineau C., Bouganim L., Pucheral P., Valduriez P., 'PicoDBMS: Validation and Experience', Proc. of the 27th International Conference on Very Large Data Bases (VLDB), demo session, Roma, Italy, September 2001. • C. Bobineau, L. Bouganim, P. Pucheral,  P. Valduriez : PicoDBMS : Scaling down database techniques for the Smartcard. Int. Conf. on VLDB, Best paper award, Cairo, 2000. • http://www.cardwerk.com/smartcards/ • http://www.fist.fr/index.php?wpe=a505 • http://electronics.howstuffworks.com/question332.htm

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