sign should take a file path

[mixmix]

currently CLI takes a raw string.

questions to consider in design:

1. what is the CLI signature, e.g.
   • entropy sign-file --verifying-key alskdalksdjalksjdasdlkjasd
   • entropy sign -f /my/file.txt
2. when it reads the file, does it assume content is utf-8 as it reads it?
   • maybe sign uses buffers in some steps, and can just pass read buffer in => to check
3. do we still support signing strings?

[rh0delta]

I am more inclined to use the -f option rather than creating a whole new command for signing a file. We can also update sign to be similar to how git works with commit messages where -m allows us to write a quick and easy string message

[mixmix]

I like the -f as well

Tasks

• 1. Write example code

  • the -f case
  • the string input case

• 2. Write up the test cases

  • if we are allowing string or file, then defend against both
  • if you sign a string in a file it must behave same as signing the string?

• 3. Research (2) above, leaving notes in this issue:

  • make sure the "file read + sign" works same as "string + sign"
  • this may be blocking on the "verify" method from SDK 🙈 (cc @frankiebee)

• 4. Once the above are done, change status back to "Up Next", "blocked" "Needs Research"

[frankiebee]

moving to blocked till we have the verify function fleshed out
see #79