##What?## An SHA-1 hash implementation in REXX.
##Why?## Because it's possible.
##Why not?##
- Because REXX is slow.
- Because REXX doesn't have fixed-size numeric variables.
- Because much time is just spent on converting between different numeric formats.
##Resources##
- Pseudocode on Wikipedia: [https://en.wikipedia.org/wiki/SHA-1#Examples_and_pseudocode]
- Debug help and inspiration from [http://csrc.nist.gov/groups/ST/toolkit/documents/Examples/SHA1.pdf]
- Further inspiration from [https://tools.ietf.org/html/rfc3174]