Question

I have an encrypted file file = File.new("encrypted.file", "r") that I would like to require in Ruby after decryption. I do not want to decrypt, save, require, and delete the file.

What I do now is:

str=""
file.each do |line|
     str+=line
end#do

str = doSomeDecryption(str)

I would like to require str in some way. Any ideas? eval(str) is not an option; it really has to be ‘requireable’.

Answer 1

Strictly speaking, require doesn’t load a file, it loads a resource; with the right overload of Kernel#require, you can do almost anything. Some folks have made versions that use open-uri to load code from a remote server. If you want to implement this in pure Ruby, you will need to use eval. See http_require (https://github.com/astrails/http_require) for its implementation.

If you want to implement this as an extension, you may be able to reduce the potential attack surface area, but you’re still going to be implementing either a save-to-disk-then-require or an eval. (Strictly speaking, although I can’t find the code in the interpreter right at the moment, require itself essentially does an eval.)