New trends highlight the use of delegated authentication solutions where identity providers do not need to synchronize user credentials with services. It is a facility for service providers and also for users who do not have to create multiple accounts. Different solutions for single sign-on and delegated authentication exist. Most of these solutions require many exchanges between the different actors involved in the protocol, an additional TLS layer and/or the use of signature schemes which, in terms of security, rely on random oracles for reasons of efficiency. In this article, we recall the concept of the best known solutions (e.g. Kerberos, OpenID, ...), briefly discuss the possibility of using one-way accumulators and define the Proxy Re-Encryption (PRE). Next, we propose a new delegated authentication protocol that allows users to authenticate anonymously on insecure networks and therefore asynchronously without direct communication between identity providers and service providers while minimizing the number of interactions. We based our solution on the use of PRE which could be instantiated by schemes based on standard assumptions. We first show how our protocol behave against different type of attack. Then in a more formal manner, we present the proof of security based on an adaptation of BAN logic method that support the use of PRE functionalities.