protecting data privacy and integrity in clouds by jyh-haw yeh computer science boise state...
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Relational Semantic Hiding Databases (RSHDB)Protecting data privacy and integrity in clouds
By Jyh-haw YehComputer Science
Boise state University
Cloud ComputingCloud computing paradigm provides a new
concept of IT management.Business purchases IT services from CloudsCost savingUnlimited computing powerCharged by usageMore secure?Better resource utilization, thus green
computing
Cloud ComputingCloud computing also has some known
problemsTrust issuesData privacy and integrity Non-transparency of data locationsLiability issue
Outsourcing DatabasesDatabase-as-a-service is an emerging service
starts to appear in cloud industry.Clients has the flexibility to design an
application as a database that is suitable for their business.
Outsource the database to clouds.Clouds is able to execute queries over the
database upon client’s requests.Clouds (may not be trusted) have the total
control of data.Data privacy/integrity is a big concern .
Encrypted DatabasesAn extreme approach to protect data privacy:
Encrypt the whole database and then outsource the encrypted database to clouds.
This approach works if a practical fully homomorphic encryption (FHE) algorithm exists.
FHE: arithmetic, rational comparisons can be applied directly to ciphers.
No practical and efficient FHE exists.
RSHDBRSHDB (relational semantic hiding
databases) is a proposed database system that is able to hide semantics from DBAs.Suitable for business to outsource their
business applications as a RSHDB instance to Clouds.
Enable the DBAs or DBMS in clouds to operate on the RSHDB databases without knowing private business information.
RSHDB: Idea of Hiding SemanticsIdea of semantic hiding in RSHDB:
An XYZ company has a PAYROLL database, in which a record in a table EMPLOYEE shows that John Smith SALARY is 63,000.
An ? company has a ? database, in which a record in a table ? shows that ? ? is 63,000.
RSHDB: Basic OperationsBasic database operations:
Arithmetic: add or multiply numeric data.Equality test: test the equality of two data items.Rational comparison: decide A> B or A < B.Substring matching: decide whether a string A
is a substring in another string BOther database operations: sorting, searching,
aggregate functions, set operations are extension/combination of basic operations.
RSHDB: Data TypesData types:
NC-type: Numeric with Comparison only.NCA-type: Numeric with both Comparison and
Arithmetic.SC-type: String with Comparison only.SCS-type: String with both Comparison and
Substring matching.
RSHDB: Design GoalPartially encrypts the database so that the
cloud is able to execute queries over encrypted data.
Encrypt enough information (but not all) to hide semantics from data operators.
Minimize the impacts for the DBMS, the SQL, the hosting clouds, and the clients.
RSHDB: Encryption StrategyUse a secure deterministic encryption for all
semantic telling information: database, table, attribute names.
String type data is also semantic telling: always encrypted.SC-type: order-preserved encryption (less
secure)SCS-type:
char-by-char (less secure) order-preserved encryption.
word-by-word order-preserved encryption.
RSHDB: Encryption StrategyNumeric data itself reveal less semantics.
NC-type: order-preserved encryption. Example: bdate data
NCA-type: no practical homomorphic encryption available for this type of data. Leave the data in clear Homomorphic encoding (not too much help for
security) Example: salary data
ImpactsThe DBMS: Need to be semantic hiding awareThe SQL: New data types for DDLThe hosting clouds:
More storage space for encrypted data. Install semantic hiding aware DBMS
The clients: Install an query API:Perform encryptionConvert SQL query to semantic hiding queryPerform decryptionReturn the result to the clients
Example DatabaseEMPLOYEE
NAME SSN DEPT_NO JOB _TYPE
BDATE SALARY
John Smith 123456789
1 Manager 1966-05-04
83,000
Frank Wong 333445555
3 Staff 1985-07-26
48,000
Joey English 453453453
2 Engineer 1978-10-03
72,000
Joe Johnson 999887777
2 Engineer 1982-03-29
70,500
DEPARTMENT
DEPT_NAME DEPT_NO LOCATION
Headquarter 1 Houston
Research 2 Boise
Finance 3 Houston
Example DatabaseT
A1 A2 A3 A4 A5 A6
X11 X12 25,300 X14 2,418,241,992
83,000
X21 X22 75,900 X24 2,441,639,298
48,000
X31 X32 50,600 X34 2,437,900,467
72,000
X41 X42 50,600 X44 2,433,063,369
70,500R
B1 B2 B3
Y11 25,300 Y13
Y21 50,600 Y23
Y31 75,900 Y33
Semantic Hiding Query (SHQ)The sensitive information or data is
encrypted in SHQ.
To make a query to a RSHDB, the SQL query must be a SHQ.
Example
Retrieve the name and salary of each employee in ‘Research’ department whose salary is more than $50,000, sort the report in ascending order of names.
SHQ Exampleselect EMPLOYEE.NAME, EMPLOYEE.SALARYfrom EMPLOYEE, DEPARTMENTwhere EMPLOYEE.DEPT_NO =
DEPARTMENT.DEPT_NO AND DEPT_NAME = ‘Research’ AND EMPLOYEE.SALARY > 50000asc EMPLOYEE.NAME;---------------------------------------------------------------------------select T.A1, T.A6from T, Rwhere T.A3 = R.B2 AND R.B1 = Y21 AND T.A6 >
50000asc T.A1;
SHQ ResultT.A1 T.A6
X41 70,500
X31 72,000
Query API decrypts the result and return to the clients
EMPLOYEE.NAME EMPLOYEE.SALARY
Joe Johnson 70,500
Joey English 72,000
Research IssuesStorage requirement.Is order-preserved encryption secure enough?
More secure encryption + order-preserved hashing?
Guessing the semantics from the range and format of NCA-type data in clear.Adding noises?
RSHDB’s DBMS has a weaker domain constraint enforcement.All encrypted data are in type of bit-string
Research IssuesChar-by-char versus word-by-word
encryption for SCS-type data.Flexibility, security and space.
Who should develop the query API?Performance downgrade:
Implementation and simulationReal world databases and queries
Future WorkDesigning algorithms for data integrity
protection for outsourced database.CompletenessNon-forgeryFreshness
Adding data integrity protection to RSHDB is challenging.