### Abstract

Research in information-flow security aims at developing methods to identify undesired information leaks within programs from private sources to public sinks. Noninterference captures this intuition. Strong security from Sabelfeld and Sands formalizes noninterference for concurrent systems.

We present an Isabelle/HOL formalization of strong security for arbitrary security lattices (Sabelfeld and Sands use a two-element security lattice in the original publication). The formalization includes compositionality proofs for strong security and a soundness proof for a security type system that checks strong security for programs in a simple while language with dynamic thread creation.

Our formalization of the security type system is abstract in the language for expressions and in the semantic side conditions for expressions. It can easily be instantiated with different syntactic approximations for these side conditions. The soundness proof of such an instantiation boils down to showing that these syntactic approximations imply the semantic side conditions.

### License

BSD License

### Topics

- Computer science/Security
- Computer science/Programming languages/Type systems

### Session Strong_Security

- Types
- Expr
- Domain_example
- MWLf
- Strong_Security
- Up_To_Technique
- Parallel_Composition
- Strongly_Secure_Skip_Assign
- Language_Composition
- Type_System
- Type_System_example

### Used by

- A Formalization of Declassification with WHAT-and-WHERE-Security

## Cite

×

Strong_Security-AFP

    @article{Strong_Security-AFP,
      author  = {Sylvia Grewe and Alexander Lux and Heiko Mantel and Jens Sauer},
      title   = {A Formalization of Strong Security},
      journal = {Archive of Formal Proofs},
      month   = {April},
      year    = {2014},
      note    = {\url{https://isa-afp.org/entries/Strong_Security.html},
                 Formal proof development},
      ISSN    = {2150-914x},
    }

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