Wiktionary
n. (context computing English) A person with an interest in encryption and privacy, especially one who uses encrypted email
Wikipedia
A cypherpunk is any activist advocating widespread use of strong cryptography and privacy-enhancing technologies as a route to social and political change. Originally communicating through the Cypherpunks electronic mailing list, informal groups aimed to achieve privacy and security through proactive use of cryptography. Cypherpunks have been engaged in an active movement since the late 1980s.
Usage examples of "cypherpunk".
However, if I were a Cypherpunk, I would view this kind of attention as a double-edged sword.
Knowledgeable persons will probably perceive similarities between the cypherpunks and the Secret Admirers, however intelligent readers should keep in mind that this is a work of fiction and that the two groups cannot be simply equated.
There is a fair amount of expository material about crypto that will be familiar to any Cypherpunk, hence not a reason to read the novel, and possibly a reason to avoid it.
Some of the characters espouse religious/spiritual views that many Cypherpunks will find ludicrous.
I hope that this document has covered most of the questions that readers of the Cypherpunks list are likely to have.
When cypherpunk Doug Barnes was researching his Caribbean project, he spent some time looking into this, because it was exactly the kind of threat he was worried about in the case of a data haven.