class Shrine::UrlSigner

Public Class Methods

Source

# File lib/shrine/plugins/derivation_endpoint.rb
714 def initialize(secret_key)
715   @secret_key = secret_key
716 end

Public Instance Methods

generate_signature (string)

Source

# File lib/shrine/plugins/derivation_endpoint.rb
755 def generate_signature(string)
756   OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA256.new, secret_key, string)
757 end

Uses HMAC-SHA-256 algorithm to generate a signature from the given string using the secret key.

sign_url (url)

Source

# File lib/shrine/plugins/derivation_endpoint.rb
719 def sign_url(url)
720   path, query = url.split("?")
721 
722   params = Rack::Utils.parse_query(query.to_s)
723   params.merge!("signature" => generate_signature(url))
724 
725   query = Rack::Utils.build_query(params)
726 
727   "#{path}?#{query}"
728 end

Returns a URL with the signature query parameter

verify_signature (string, signature)

Source

# File lib/shrine/plugins/derivation_endpoint.rb
745 def verify_signature(string, signature)
746   if signature.nil?
747     fail InvalidSignature, "missing \"signature\" param"
748   elsif !Rack::Utils.secure_compare(signature, generate_signature(string))
749     fail InvalidSignature, "provided signature does not match the calculated signature"
750   end
751 end

verify_url (url)

Source

# File lib/shrine/plugins/derivation_endpoint.rb
734 def verify_url(url)
735   path, query = url.split("?")
736 
737   params    = Rack::Utils.parse_query(query.to_s)
738   signature = params.delete("signature")
739 
740   query = Rack::Utils.build_query(params)
741 
742   verify_signature("#{path}?#{query}", signature)
743 end

Calculcates the signature from the URL and checks whether it matches the value in the signature query parameter. Raises InvalidSignature if the signature parameter is missing or its value doesn’t match the calculated signature.