In a general aspect, a supersingular isogeny-based cryptography process is performed. In some aspects, a first generator point is computed based on a secret integer of a first entity and a pair of elliptic curve points defined by a supersingular isogeny-based cryptosystem. An image curve is computed based on the secret integer, and a shared secret value is computed based on the image curve. An encrypted generator point is computed from the first generator point and the shared secret value. A public key of the first entity is sent to a second entity to enable the second entity to compute the shared secret value. The encrypted generator point is sent to the second entity to enable the second entity to validate the public key of the first entity.