title: bad decrypt error in ruby
body: <p>While executing the <code>cipher.final</code>, It says <code>bad decrypt</code> error. I tried to find out the problem.But,I can't find . Can you tell what is wrong with my code?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>require 'openssl'
  require 'base64'
  require 'hex_string'
  
   result_h ="4fcd6b1ac843a2f8bf13f2e53dd5c1544fcd6b1ac843a2f8"
   key = result_h.to_byte_string
  
  encrypt_str="79994A6EF73DA76C";
  cipher = OpenSSL::Cipher.new("DES-EDE3-CBC")
  cipher.decrypt
  cipher.key = key
  data = encrypt_str.to_byte_string
  res = cipher.update( data )
  res &lt;&lt; cipher.final
  result_h= res.unpack("H*")[0]
  puts result_h.inspect;
  </code></pre>
  
  <p>Error is:</p>
  
  <pre><code>in `final': bad decrypt (OpenSSL::Cipher::CipherError)
  </code></pre>