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- Judicaël Courant, Marion Daubignard, Cristian Ene, Pascal Lafourcade, Yassine Lakhnech
- ACM Conference on Computer and Communications…
- 2008

Chosen-ciphertext security is by now a standard security property for asymmetric encryption. Many generic constructions for building secure cryptosystems from primitives with lower level of security have been proposed. Providing security proofs has also become standard practice. There is, however, a lack of automated verification procedures that analyze… (More)

- Judicaël Courant
- TLCA
- 1997

Several proof-assistants rely on the very formal basis of Pure Type Systems (PTS) as their foundations. We are concerned with the issues involved in the development of large proofs in these provers such as namespace management, development of reusable proof libraries and separate verification. Although implementations offer many features to address them,… (More)

We show how the proof-assistant Coq helped us formally verify security properties of an API. As far as we know, this is the rst mathematical proof of security properties of an API. The API we veri-ed is a xed version of Bond's modelization of IBM's Common Cryptographic Architecture. We explain the methodology we followed, sketch our proof and explain the… (More)

- Judicaël Courant
- TAPSOFT
- 1997

The SML-like module systems are small typed languages of their own. As is, one would expect a proof of their soundness following from a proof of subject reduction. Unfortunately, the subject-reduction property and the preservation of type abstraction seem to be incompatible. As a consequence, in relevant module systems, the theoretical study of reductions… (More)

- Judicaël Courant, Cristian Ene, Yassine Lakhnech
- FSTTCS
- 2007

Type systems for secure information flow aim to prevent a program from leaking information from variables that hold secret data to variables that hold public data. In this work we present a type system to address deterministic encryption. The intuition that encrypting a secret yields a public value, that can be stored in a public variable, is faithful for… (More)

- Judicaël Courant
- Electr. Notes Theor. Comput. Sci.
- 2002

This paper presents a new lambda-calculus with singleton types, called λ βδ ≤{}. The main novelty of λ βδ ≤{} is the introduction of a new reduction, the δ-reduction, replacing any variable declared of singleton type by its value, and the definition of equality as the syntactic equality of βδ-normal forms. The δ-reduction has a very odd behavior on untyped… (More)

- Judicaël Courant, Marion Daubignard, Cristian Ene, Pascal Lafourcade, Yassine Lakhnech
- Concurrency, Compositionality, and Correctness
- 2010

Chosen-ciphertext security is by now a standard security property for asymmetric encryption. Many generic constructions for building secure cryptosystems from primitives with lower level of security have been proposed. Providing security proofs has also become standard practice. There is, however, a lack of automated verification procedures that analyse… (More)

- Judicaël Courant
- TPHOLs
- 2002

- Judicaël Courant
- J. Funct. Program.
- 2007

- Jean-François Monin, Judicaël Courant
- Trends in Functional Programming
- 2006

We study a normalization function in an algebra of terms quotiented by an associa-tive, commutative and involutive operator (logical xor). This study is motivated by the formal verification of cryptographic systems, where a normalization function for xor-terms turns out to play a key role. Such a function is easy to define using general recursion. However,… (More)