Fast initialization of secure HMB

The present disclosure generally relates to data storage devices and related methods that use secure host memory buffers (HMBs) and low latency operations. A controller of the data storage device is configured to access the HMB, where the HMB stores a Merkle Tree. When the HMB is initialized, the controller determines a number of hash levels of the Merkle Tree. Each hash level of the Merkle Tree comprises one or more hashes. When storing location data in a target data block of the Merkle Tree, the controller is configured to initialize only the hashes along a path between a top hash and the target data block. Each hash along the path has a non-initialized hash coupled to a common hash. The non-initialized hash is programmed with a non-initialized bit, such that only the relevant hashes and data blocks are initialized.