aka:Message Digest

• SHA1

  $ openssl sha1 first-file.txt 
  SHA1(first-file.txt)= 4c49b08e9b258e0e5867d76ce583c159597b6857
  $ openssl sha1 < first-file.txt 
  (stdin)= 4c49b08e9b258e0e5867d76ce583c159597b6857
  $ 
  

  • T.B.D.