decode.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

require 'base64'

hexagrams = "䷀䷪䷍䷡䷈䷄䷙䷊䷉䷹䷥䷵䷼䷻䷨䷒䷌䷰䷝䷶䷤䷾䷕䷣䷘䷐䷔䷲䷩䷂䷚䷗䷫䷛䷱䷟䷸䷯䷑䷭䷅䷮䷿䷧䷺䷜䷃䷆䷠䷞䷷䷽䷴䷦䷳䷎䷋䷬䷢䷏䷓䷇䷖䷁"
base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

puts Base64.decode64(gets.tr(hexagrams, base64chars))

encode.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

require 'base64'

hexagrams = "䷀䷪䷍䷡䷈䷄䷙䷊䷉䷹䷥䷵䷼䷻䷨䷒䷌䷰䷝䷶䷤䷾䷕䷣䷘䷐䷔䷲䷩䷂䷚䷗䷫䷛䷱䷟䷸䷯䷑䷭䷅䷮䷿䷧䷺䷜䷃䷆䷠䷞䷷䷽䷴䷦䷳䷎䷋䷬䷢䷏䷓䷇䷖䷁"
base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

puts (Base64.encode64(gets).tr(base64chars, hexagrams))