require 'digest'
require 'openssl'

str = '内容😝'
key = ''

p Digest::SHA1.hexdigest str
p OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA1.new, key, str)

=begin
"5d968ccf64b6f17441c39d076f2fb53119cbeafc"
"d0d3ec791cee9b44a21338973729a080572a6e81"
=end

这里的 key 要怎么选才能得到相同的 hash 呢？ (其实问题的本质是不懂怎么看源码~)