DATABASE CONTROLS
Chapter 14
Access Controls

Discretionary Access Controls
Types of Restrictions :
1. Name-dependent restrictions
2. Content-dependent restrictions
3. Context-dependent restrictions
4. History-dependent restrictions
Horizontial propagation of privileges limited to three users :
User B
User A
User C
privileges
User D
privileges
privileges
User F
User E
Vertical propagation of privileges limited to three users :
User B
User A
privileges
User F
User C
privileges
privileges
User E
User D


Mandatory Access Controls
- Classification level
- Clearance level
- Polyinstantiation Approach
Some Implementation Issues
Integrity Controls

Entity-Relationship Model Integrity Constraints
1. Uniqueness
2. Maximum cardinality
3. Minimum cardinality
4. Entity identifier
5. Value type of identifier
6. Value set of identifier


Relational Data Model Integrity Constraints
1. Key
2. Entity
3. Referential
Object Data Model Integrity Constraints
1. Unique identifier
2. Unique key
3. Value type of attribute
4. Value set of attribute
5. Types and inheritance
Application Software Controls
Update protocols :
 Sequence check transaction and master
files
 Ensure all records on files are processed
 Process multiple transactions for a single
record in the correct order
 Maintain a suspense account
Report Protocols :
 Print control data for internal tables
 Print run-to-run control totals
 Print suspense account entries
Concurrency Controls


Nature of the shared data resource problem
The problem of Deadlock :
1. Lockout
2. Concurrency
3. Additional request
4. No preemption
5. Circular wait



Solutions to Deadlock
Preventing Deadlock
1. Atomicity
2. Consistency
3. Isolation
4. Durability
Distributed Database Concurrency Controls
1. Schedulers are replicated and stored with
each version of the data item.
2. One version of the data item and its
associated scheduler is designated as the
primary copy.
Cryptographic controls




File Key
Secondary Key
Master Key
Access to the key
Several disadvantages arise
File Handling Controls


Internal data item :
1. Internal label
2. Generation Number
3. Retention date
4. Control totals
Several hardware controls
Audit Trail Controls


Accounting Audit Trail :
1. It must attach a unique time stamp to all
transaction applied against the database.
2. The database subsystem must attach
beforeimages and afterimages.
3. The database subsystem must provide
facilities to define, create, modify, delete, and
retrive data in the audit trail.
Operations Audit Trail.