  An important aspect of the propagation delay in blockchain networks is the
block verification time, which is also responsible for the so-called verifier's
dilemma. Models for the block verification time can help to understand and
improve the verification process. Moreover, modeling the verification time is
necessary for blockchain network simulations. In this paper, we present JOIST,
a new model for the block verification time of Zcash. We identify
computationally complex operations in the verification process of Zcash, and
derive our model based on characteristic transaction features. We evaluate
JOIST and show that the model is consistently more accurate than existing
models, which consider the block size only.
