Class: Shrine::UrlSigner

Inherits:
Object
  • Object
show all
Defined in:
lib/shrine/plugins/derivation_endpoint.rb

Defined Under Namespace

Classes: InvalidSignature

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(secret_key) ⇒ UrlSigner

Returns a new instance of UrlSigner.



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# File 'lib/shrine/plugins/derivation_endpoint.rb', line 714

def initialize(secret_key)
  @secret_key = secret_key
end

Instance Attribute Details

#secret_key ⇒ Object (readonly)

Returns the value of attribute secret_key.



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# File 'lib/shrine/plugins/derivation_endpoint.rb', line 712

def secret_key
  @secret_key
end

Instance Method Details

#generate_signature(string) ⇒ Object

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



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# File 'lib/shrine/plugins/derivation_endpoint.rb', line 755

def generate_signature(string)
  OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA256.new, secret_key, string)
end

#sign_url(url) ⇒ Object

Returns a URL with the signature query parameter



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# File 'lib/shrine/plugins/derivation_endpoint.rb', line 719

def sign_url(url)
  path, query = url.split("?")

  params = Rack::Utils.parse_query(query.to_s)
  params.merge!("signature" => generate_signature(url))

  query = Rack::Utils.build_query(params)

  "#{path}?#{query}"
end

#verify_signature(string, signature) ⇒ Object 



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# File 'lib/shrine/plugins/derivation_endpoint.rb', line 745

def verify_signature(string, signature)
  if signature.nil?
    fail InvalidSignature, "missing \"signature\" param"
  elsif !Rack::Utils.secure_compare(signature, generate_signature(string))
    fail InvalidSignature, "provided signature does not match the calculated signature"
  end
end

#verify_url(url) ⇒ Object

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.



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# File 'lib/shrine/plugins/derivation_endpoint.rb', line 734

def verify_url(url)
  path, query = url.split("?")

  params    = Rack::Utils.parse_query(query.to_s)
  signature = params.delete("signature")

  query = Rack::Utils.build_query(params)

  verify_signature("#{path}?#{query}", signature)
end