class Shrine::UrlSigner

  1. lib/shrine/plugins/derivation_endpoint.rb
Superclass: Object

Methods

Public Class

  1. new

Public Instance

  1. generate_signature
  2. secret_key
  3. sign_url
  4. verify_signature
  5. verify_url

Attributes

secret_key [R]

Public Class methods

new(secret_key)
[show source] 
    # File lib/shrine/plugins/derivation_endpoint.rb
712 def initialize(secret_key)
713   @secret_key = secret_key
714 end

Public Instance methods

generate_signature(string)

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

[show source] 
    # File lib/shrine/plugins/derivation_endpoint.rb
753 def generate_signature(string)
754   OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA256.new, secret_key, string)
755 end
sign_url(url)

Returns a URL with the signature query parameter

[show source] 
    # File lib/shrine/plugins/derivation_endpoint.rb
717 def sign_url(url)
718   path, query = url.split("?")
719 
720   params = Rack::Utils.parse_query(query.to_s)
721   params.merge!("signature" => generate_signature(url))
722 
723   query = Rack::Utils.build_query(params)
724 
725   "#{path}?#{query}"
726 end
verify_signature(string, signature)
[show source] 
    # File lib/shrine/plugins/derivation_endpoint.rb
743 def verify_signature(string, signature)
744   if signature.nil?
745     fail InvalidSignature, "missing \"signature\" param"
746   elsif !Rack::Utils.secure_compare(signature, generate_signature(string))
747     fail InvalidSignature, "provided signature does not match the calculated signature"
748   end
749 end
verify_url(url)

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.

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