Hal Finney, a cryptographer and one of the earliest users and developers of the virtual currency Bitcoin, died on Thursday in Phoenix. He was 58.

Mr. Finney had been paralyzed by amyotrophic lateral sclerosis, or A.L.S., and was taken off life support at Paradise Valley Hospital, his wife, Fran Finney, said. She said his body was immediately prepared for cryonic preservation by the Alcor Life Extension Foundation in Scottsdale, Ariz., according to his wishes.

A graduate of the California Institute of Technology, Mr. Finney was a longtime futurist who put his programming skills to work in the service of his ideals, particularly his desire to see the privacy of individuals protected.

In 1991, he began doing volunteer work for a new software project known as Pretty Good Privacy, or P.G.P., and immediately became one of the central players in developing the program. P.G.P. aimed to make it possible for people everywhere to encrypt electronic communication in a way that could not be read by anyone other than the intended recipient. The program used relatively new innovations in encryption that are still thought to be invulnerable to code breakers.