Systems and methods for efficient computation of stream ciphers. An example system for implementing a stream cipher, may comprise: a sub-round computation circuit of a first type configured to perform a subset of transformations of a cipher computation round on a round input state, each transformation of the subset of transformations including at least one of: a bitwise addition operation, a bitwise exclusive disjunction operation, or a bitwise rotation operation. The sub-round computation circuit of the first type may comprise: one or more of sub-round computation circuits of a second type, wherein each sub-round computation circuit of the second type is configured to perform the subset of transformations of the cipher computation round on a respective part of the round input state.