Careers > Enhance the security of networking libraries with formally proven message handling in SPARK
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Enhance the security of networking libraries with formally proven message handling in SPARK

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Enhance the security of networking libraries with formally proven message handling in SPARK


SPARK is a subset of the Ada programming language, together with formal verification tools which allow giving mathematical guarantees about SPARK programs, from correct data flows to absence of runtime errors to correct implementation of functional requirements. SPARK is open source and freely available to the Community on as well as professionally supported by AdaCore, which co-develops SPARK with Altran and Inria. RecordFlux ( is a Domain Specific Language for specifying binary message formats and generating a provably correct implementation of message handling in SPARK. RecordFlux is also developed by AdaCore in open source.  


The subject of this internship is to use RecordFlux and SPARK to replace the hand-written message handling code in parts of the CycloneTCP/CycloneSSL open source libraries in C developed by company Oryx Embedded ( A previous internship successfully replaced part of the Socket and TCP implementation in C with a manually-written implementation in SPARK, including detailed specification of the underlying state machine of the TCP protocol. This work led to the discovery of subtle bugs in the C implementation, and gave stronger confidence that the resulting SPARK implementation is correctly implementing critical properties of the protocol. The results of this work have been published at IEEE SecDev 2021 conference ( This new internship focuses on message handling, which is a known source of security vulnerabilities (e.g. the recent precisely on TCP implementations) as manually validating the content of binary messages is error-prone. The objective here is twofold: demonstrate that the message handling part of existing protocol implementations can be replaced by code generated from a DSL which is proven to be correct-by-construction; extend the guarantees provided by formal verification to other parts of the libraries that call in the message handling part.


Skills required: The work will require interacting closely with engineers from AdaCore on the language/proof side on and RecordFlux technology, and Oryx Embedded on the library/protocol side.


Timeframe and location:


The internship will take place in the offices of AdaCore in Paris. Trips to Grenoble may be required to work with engineers from Oryx Embedded, in addition to frequent remote interactions.

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