34 research outputs found
A Verified Information-Flow Architecture
SAFE is a clean-slate design for a highly secure computer system, with
pervasive mechanisms for tracking and limiting information flows. At the lowest
level, the SAFE hardware supports fine-grained programmable tags, with
efficient and flexible propagation and combination of tags as instructions are
executed. The operating system virtualizes these generic facilities to present
an information-flow abstract machine that allows user programs to label
sensitive data with rich confidentiality policies. We present a formal,
machine-checked model of the key hardware and software mechanisms used to
dynamically control information flow in SAFE and an end-to-end proof of
noninterference for this model.
We use a refinement proof methodology to propagate the noninterference
property of the abstract machine down to the concrete machine level. We use an
intermediate layer in the refinement chain that factors out the details of the
information-flow control policy and devise a code generator for compiling such
information-flow policies into low-level monitor code. Finally, we verify the
correctness of this generator using a dedicated Hoare logic that abstracts from
low-level machine instructions into a reusable set of verified structured code
generators
The Meaning of Memory Safety
We give a rigorous characterization of what it means for a programming
language to be memory safe, capturing the intuition that memory safety supports
local reasoning about state. We formalize this principle in two ways. First, we
show how a small memory-safe language validates a noninterference property: a
program can neither affect nor be affected by unreachable parts of the state.
Second, we extend separation logic, a proof system for heap-manipulating
programs, with a memory-safe variant of its frame rule. The new rule is
stronger because it applies even when parts of the program are buggy or
malicious, but also weaker because it demands a stricter form of separation
between parts of the program state. We also consider a number of pragmatically
motivated variations on memory safety and the reasoning principles they
support. As an application of our characterization, we evaluate the security of
a previously proposed dynamic monitor for memory safety of heap-allocated data.Comment: POST'18 final versio
CoSMed: a confidentiality-verified social media platform
This paper describes progress with our agenda of formal verification of information-flow security for realistic systems. We present CoSMed, a social media platform with verified document confidentiality. The system’s kernel is implemented and verified in the proof assistant Isabelle/HOL. For verification, we employ the framework of Bounded-Deducibility (BD) Security, previously introduced for the conference system CoCon. CoSMed is a second major case study in this framework. For CoSMed, the static topology of declassification bounds and triggers that characterized previous instances of BD security has to give way to a dynamic integration of the triggers as part of the bound
CoSMed: a confidentiality-verified social media platform
This paper describes progress with our agenda of formal verification of information-flow security for realistic systems. We present CoSMed, a social media platform with verified document confidentiality. The system’s kernel is implemented and verified in the proof assistant Isabelle/HOL. For verification, we employ the framework of Bounded-Deducibility (BD) Security, previously introduced for the conference system CoCon. CoSMed is a second major case study in this framework. For CoSMed, the static topology of declassification bounds and triggers that characterized previous instances of BD security has to give way to a dynamic integration of the triggers as part of the bound
A conference management system with verified document confidentiality
We present a case study in verified security for realistic systems: the implementation of a conference management system, whose functional kernel is faithfully represented in the Isabelle theorem prover, where we specify and verify confidentiality properties. The various theoretical and practical challenges posed by this development led to a novel security model and verification method
generally applicable to systems describable as input–output automata
A conference management system with verified document confidentiality
We present a case study in verified security for realistic systems: the implementation of a conference management system, whose functional kernel is faithfully represented in the Isabelle theorem prover, where we specify and verify confidentiality properties. The various theoretical and practical challenges posed by this development led to a novel security model and verification method
generally applicable to systems describable as input–output automata