digest.rb

require 'digest'

# Get SHA256 Hash of a file
puts Digest::SHA256.hexdigest File.read "data.dat"
# Get MD5 Hash of a file
puts Digest::MD5.hexdigest File.read "data.dat"
# Get MD5 Hash of a string
puts Digest::SHA256.hexdigest "Hello World"

# Get SHA256 Hash of a string using update
sha256 = Digest::SHA256.new
sha256.update "Hello"
sha256.update " World"
puts sha256.hexdigest