Apparatus and method for managing entropy in a cryptographic processing system, such as but not limited to a solid-state drive (SSD). In some embodiments, a processing device is operated to transfer data between a host device and a non-volatile memory (NVM). In response to the detection of a power down event associated with the processing device, entropy associated with the power down event is collected and stored in a memory. Upon a subsequent reinitialization of the processing device, the entropy is conditioned and used as an input to a cryptographic function to subsequently transfer data between the host device and the NVM. In some embodiments, the entropy is obtained from the state of a hardware timer that provides a monotonically increasing count for timing control. In other embodiments, the entropy is obtained from a RAID buffer used to store data to a die set of the NVM.