# Bell–LaPadula model

> state machine model used for enforcing access control in government and military applications

**Wikidata**: [Q815667](https://www.wikidata.org/wiki/Q815667)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Bell–LaPadula_model)  
**Source**: https://4ort.xyz/entity/belllapadula-model

## Summary
The **Bell–LaPadula model** is a state machine model used for enforcing access control in government and military applications, primarily to ensure confidentiality. It was designed to prevent unauthorized access to classified information by regulating how subjects interact with objects based on security levels.

## Key Facts
- The Bell–LaPadula model is a **computer security model** that enforces **confidentiality policies**.
- It is used in **government and military systems** to protect sensitive data.
- It is based on a **state machine model**, meaning it defines secure system states and valid state transitions.
- The model enforces two primary rules:
  - **Simple Security Property**: A subject can read an object only if the subject’s clearance level is greater than or equal to the object’s classification.
  - **\* (star) Property**: A subject can write to an object only if the object’s classification is greater than or equal to the subject’s clearance level.
- It is classified as both a **computer security model** and a **finite-state machine**.
- Related models include the **Biba model** (integrity), **Clark–Wilson model** (integrity policy), and **Graham-Denning model** (access control).
- It is part of the foundation for **FLASK (Flux Advanced Security Kernel)**, an operating system security architecture.
- Aliases include:
  - Modelo de Bell-LaPadula (Spanish)
  - Modèle de Bell et La Padula (French)
  - 贝尔-拉帕杜拉模型 (Chinese)
  - التحكم بالوصول الإلزامي (Arabic)
- The model has no specific founding date or creator listed in the provided material but is foundational in **formal access control theory**.
- It is described in academic literature, including *Security Engineering: A Guide to Building Dependable Distributed Systems*, 2nd edition, chapter 8.3.
- The model is implemented through **computer security policies** that define access control rules.
- It is available in multiple language versions on Wikipedia: **ar, az, bn, de, en, es, fr, it, ja, ko, lmo, pt, ru, uk, vi, zh**.
- Sitelink count: **16** (as of Wikidata).
- Microsoft Academic ID (discontinued): **2778340491**.

## FAQs

### Q: What is the Bell–LaPadula model used for?
A: It is used to enforce access control in government and military systems to ensure confidentiality by preventing unauthorized access to classified information. It defines secure state transitions and access rules based on security levels.

### Q: How does the Bell–LaPadula model enforce security?
A: It enforces two key rules:
- **Simple Security Property**: Users can only read data at or below their clearance level.
- **\* (star) Property**: Users can only write to data at or above their clearance level.
These rules prevent both upward and downward information flow that could compromise confidentiality.

### Q: What are the related security models?
A: Related models include:
- **Biba model**: Focuses on data integrity.
- **Clark–Wilson model**: Emphasizes integrity policies.
- **Graham-Denning model**: Governs secure object creation and deletion.
- **HRU (Harrison-Ruzzo-Ullman) model**: General framework for access control.

### Q: Is the Bell–LaPadula model based on theory or practice?
A: It is based on a **formal model of access rights** and computation, making it a theoretical framework implemented through **computer security policies**.

### Q: What systems use the Bell–LaPadula model?
A: It is primarily used in **military and government systems** where confidentiality is critical, such as secure operating systems and classified information systems.

### Q: What is the Bell–LaPadula model's relationship to FLASK?
A: The Bell–LaPadula model is foundational to **FLASK (Flux Advanced Security Kernel)**, an OS security architecture that uses security models to define and enforce access control.

## Why It Matters
The Bell–LaPadula model is a foundational framework for **confidentiality enforcement** in high-security environments. It provides a formal method for ensuring that classified information is accessed only by authorized users with appropriate clearances. This model is essential in **military and government systems**, where unauthorized data exposure can have national or global consequences. It also influences modern security architectures like **FLASK**, and its principles are taught in academic and professional security curricula. By defining strict access control rules, it prevents both **information leakage** and **privilege escalation**, making it a cornerstone of secure system design.

## Notable For
- Being a **state machine model** used to enforce **access control**.
- Enforcing **confidentiality** in **military and government systems**.
- Implementing the **Simple Security Property** and **\* Property** to prevent unauthorized read/write access.
- Influencing **FLASK** and other **security kernel architectures**.
- Being a **formal model of access rights**, grounded in computation theory.
- Supporting **integrity-focused models** like Biba and Clark–Wilson through contrast.
- Having **multilingual documentation** and global recognition (16 language versions).

## Body

### History and Development
The Bell–LaPadula model was developed in the 1970s as part of a broader effort to formalize access control in secure computing systems. It was designed to address the need for **confidentiality enforcement** in environments where classified information must be protected from unauthorized access. While no specific creator or date is cited, the model is foundational in **formal access control theory** and has influenced major security frameworks like **FLASK**.

### Core Principles and Mechanisms
The model enforces two key security properties:
- **Simple Security Property**: A subject can read an object only if the subject’s clearance level is greater than or equal to the object’s classification.
- **\* (star) Property**: A subject can write to an object only if the object’s classification is greater than or equal to the subject’s clearance level.

These rules prevent **information leakage** (reading up) and **privilege escalation** (writing down), ensuring that data flows only in secure directions.

### Classification and Theoretical Basis
The Bell–LaPadula model is a **state machine model**, meaning it defines valid system states and transitions between them. It is also a **computer security model**, used to specify and enforce **confidentiality policies**. It is based on a **formal model of access rights**, distinguishing it from purely practical models.

### Implementation and Use Cases
The model is implemented through **computer security policies**, which define:
- Who can access what resources (**access control**)
- How data confidentiality is maintained (**confidentiality models**)
- How systems prevent unauthorized access (**admission control**)

It is used primarily in **military and government systems**, where data confidentiality is critical. It also underpins **FLASK**, an OS security architecture that uses security models to enforce access control.

### Related Models and Frameworks
The Bell–LaPadula model is part of a broader family of **computer security models**:
- **Biba model**: Focuses on **data integrity**.
- **Clark–Wilson model**: Emphasizes **integrity policies**.
- **Graham-Denning model**: Governs **secure object creation and deletion**.
- **HRU (Harrison-Ruzzo-Ullman) model**: General framework for **access control**.

These models are used in various combinations to enforce different aspects of security, such as **confidentiality**, **integrity**, and **availability**.

### International Recognition and Localization
The Bell–LaPadula model is documented in multiple languages, including:
- **Arabic** (التحكم بالوصول الإلزامي)
- **Chinese** (贝尔-拉帕杜拉模型)
- **French** (Modèle de Bell et La Padula)
- **Spanish** (Modelo de Bell LaPadula)
- **Italian, Japanese, Korean, Portuguese, Russian, Vietnamese**, and others.

This multilingual support reflects its global relevance in **government and military systems**.

### Influence on Modern Security
The model is foundational to **FLASK (Flux Advanced Security Kernel)**, an OS security architecture that uses security models to define and enforce access control. It also influences **web security mechanisms** like the **same-origin policy**, which prevents cross-origin interference.

### Aliases and Identifiers
- **Aliases**: 
  - Modelo Bell LaPadula
  - Modèle de Bell et La Padula
  - 贝尔-拉帕杜拉模型
  - التحكم بالوصول الإلزامي
- **Wikidata ID**: Q5157371
- **Microsoft Academic ID (discontinued)**: 2778340491
- **Sitelink count**: 16

### Academic and Technical References
The model is discussed in *Security Engineering: A Guide to Building Dependable Distributed Systems*, 2nd edition, chapter 8.3. This text provides a comprehensive overview of its use in **formal access control theory** and its implementation in **secure system design**.

## References

1. Freebase Data Dumps. 2013