A computing system provides clock readings from an untrusted code to trusted code, where the trusted code is executed in a secure enclave and the untrusted code is executed outside the secure enclave. The computing system allocates a pointer to shared memory that is shared between the untrusted code and the trusted code. Under control of the untrusted code, the computing system periodically writes a clock reading to the shared memory. Under control of the trusted code, the computing system reads the clock reading stored in shared memory. The untrusted code cannot determine when the trusted code reads a clock reading.