ABSTRACT: This work proposes a new cryptosystem, combining a Diffie-Hellman protocol in which hyperelliptic curves over GF(2n) are implemented, with a Tree Parity Machine (TPM) synchronization. Security proposed for this cryptosystem is focused on overcoming a weakness of neuronal synchronization. Specifically, the stimulus vector that is public, which allows an attacker to try to synchronize with one of the participants of the synchronization. Focusing on this weakness, there are the following attacks: genetic attack, geometric attack and probabilistic attack. In the proposed cryptosystem, the initial stimulus vector will be hidden, because this vector is obtained as the common secret key in the Diffie-Hellman protocol. Then in each iteration, the stimulus vectors will be kept secret. This condition causes the learning time tlear to increase by a term of approximately 115% regarding the synchronization time tsync on average when the proposed cryptosystem is compared to the classic TPM synchronization.