In cryptography, MOSQUITO was a stream cypher algorithm designed by Joan Daemen and Paris Kitsos. It was submitted to the eSTREAM Project of the eCRYPT network. After the initial design was broken by Joux and Muller, a tweaked version named MOUSTIQUE was proposed which made it to Phase 3 of the eSTREAM evaluation process as the only self-synchronizing cipher remaining. However, MOUSTIQUE was subsequently broken by Käsper et al., leaving the design of a secure and efficient self-synchronising stream cipher as an open research problem.

Mosquitoes are small, midge-like flies which comprise the family Culicidae. Females of most species are ectoparasites, whose tube-like mouthparts (called a proboscis) pierce the hosts' skin to consume blood. The word "mosquito" (formed by mosca and diminutive ito) is Spanish for "little fly". Thousands of species feed on the blood of various kinds of hosts, mainly vertebrates, including mammals, birds, reptiles, amphibians, and even some kinds of fish. Some mosquitoes also attack invertebrates, mainly arthropods. Though the loss of blood is seldom of any importance to the victim, the saliva of the mosquito often causes an irritating rash that is a serious nuisance. Much more serious though, are the roles of many species of mosquitoes as vectors of diseases. In passing from host to host, some transmit extremely harmful infections such as malaria, yellow fever, west Nile virus, dengue fever, filariasis, Zika virus and other arboviruses, rendering it the deadliest animal family in the world.