What encryption does vim -x use?

Question

I read man vim, :h -x and :h encryption none of this actually says what algorithm it's encrypted with.

Answer 1

:h 'cryptmethod' says that PkZip and Blowfish (new in Vim 7.3) are possible encryption methods. A look around FEAT_CRYPT in vim/src/misc2.c confirms it.

The weak encryption method is documented in PKWARE's zip file format documentation, and the new strong encryption is documented on Bruce Schneier's Blowfish page.

Answer 2

I know that they added support for blowfish encryption in 7.3. Other than that it's zip.

If you're using 7.3 go:

:set cryptmethod?

to see what method you're using.