Résumé : Security-by-Contract (S×C) is a novel paradigm providing security assurances for mobile applications. In this work, we present an extension of S×C enriched with an automatic trust management infrastructure. Indeed, we enhance the already existing architecture by adding new modules and configurations for contracts managing. At deploy-time, our system decides the run-time configuration depending on the credentials of the contract provider. Roughly, the run-time environment can both enforce a security policy and monitor the declared contract. According to the actual behaviour of the running program our architecture updates the trust level associated with the contract provider. The main advantage of this method is an automatic management of the level of trust of software and contract releasers.