Methods and apparatus are provided for generation of forward secure pseudorandom numbers that are resilient to such forward clock attacks. A forward secure pseudorandom number is generated by obtaining a first state si corresponding to a current leaf node νi in a hierarchical tree, wherein the current leaf νi produces a first pseudorandom number ri−1; updating the first state si to a second state si+t corresponding to a second leaf node νi+t; and computing a second pseudorandom number ri+t−1 corresponding to the second leaf node νi+t, wherein the second pseudorandom number ri+t−1 is based on a forward clock reset index that identifies an instance of the hierarchical tree, wherein the instance of the hierarchical tree is incremented when one or more criteria indicating a forward clock attack are detected. The forward clock reset index can be encoded in a forward secure manner in the hierarchical tree.