Format encrypted string to pass as URL param - ruby-on-rails

Question

I am using the 'encryptor' gem to scramble a string that I want to include as a URL parameter on a redirect. Unfortunately, the URI::encode function does not turn the encrypted string into an acceptable format to be included into the URL. How can I turn it into something that can be passed as a URL parameter?
salt = Time.now.to_i.to_s
secret_key = 'secret'
iv = OpenSSL::Cipher::Cipher.new('rc2').random_iv
encrypted_url = Encryptor.encrypt("some url parameter as string", :algorithm => 'rc2', :key => secret_key, :iv => iv, :salt => salt)
url = URI::encode(encrypted_url)
redirect_to 'http://domain.com/' + url

Answer 1

Base64 is recommended in this use case.
Addressable
Genereally encoding URL's should be done with the Addressable gem. In your case you're using non UTF-8 characters which will raise an error with the standard parse. So you'll need to use the encode feature of addressable.
require 'encryptor'
require 'openssl'
require 'addressable/uri'
salt = Time.now.to_i.to_s
# => "1414221973"
secret_key = 'secret'
# => "secret"
iv = OpenSSL::Cipher::Cipher.new('rc2').random_iv
# => "\x97\xE5\x83\xFF#\x97\x0Fn"
encrypted_url = Encryptor.encrypt("some url parameter as string", :algorithm => 'rc2', :key => secret_key, :iv => iv, :salt => salt)
# => "\xD6\x1D\x1A\x8A\x06f\x91\x91I\xD2\x04\xEB\x81\xFF\xCC&\xFA\e\x94,\xAE\xA0\xDA\xFA\xD2\xD8w\xF3\xD4\x8E\xB64"
url = Addressable::URI.encode_component(encrypted_url)
# => "%D6%1D%1A%8A%06f%91%91I%D2%04%EB%81%FF%CC&%FA%1B%94,%AE%A0%DA%FA%D2%D8w%F3%D4%8E%B64"
redirect_to 'http://domain.com/?' + url # You'll want to prepend url params with a question mark
For the URL I recommend give the encrypted string a param name
'http://domain.com/?encsite=' + url
NOTE: I'm uncertain as to whether these % symbols are permitted as is in URLs. You may need to URI.encode the result to exchange % to %25.
In my tests with Addressable I got the following:
require 'addressable/uri'
#...
url = Addressable::URI.parse(encrypted_url)
# => #<Addressable::URI:0x93bcf0 URI:��f��I�����&�,������w�Ԏ�4>
url.normalize
# ArgumentError: invalid byte sequence in UTF-8
# SO ENCODE INSTEAD
url = Addressable::URI.encode_component(encrypted_url)
# => "%D6%1D%1A%8A%06f%91%91I%D2%04%EB%81%FF%CC&%FA%1B%94,%AE%A0%DA%FA%D2%D8w%F3%D4%8E%B64"
For more in depth Addressable encoding information you can find the list of methods with description here: http://www.rubydoc.info/gems/addressable/Addressable/URI
Base64
You can just use Base64 instead. E.G.)
require 'base64'
#...
url = Base64.encode64(encrypted_url)
# => "1h0aigZmkZFJ0gTrgf/MJvoblCyuoNr60th389SOtjQ=\n"
url.chomp!
# => "1h0aigZmkZFJ0gTrgf/MJvoblCyuoNr60th389SOtjQ="
Base64.decode64(url) == encrypted_url
# => true