Class: XMLSecurity::SignedDocument

Inherits:
REXML::Document
  • Object
show all
Defined in:
lib/xml_security.rb

Instance Method Summary collapse

Instance Method Details

#validate(idp_cert_fingerprint, logger = nil) ⇒ Object 



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# File 'lib/xml_security.rb', line 36

def validate (idp_cert_fingerprint, logger = nil)
  # get cert from response
  base64_cert             = self.elements["//ds:X509Certificate"].text
  cert_text               = Base64.decode64(base64_cert)
  cert                    = OpenSSL::X509::Certificate.new(cert_text)

  # check cert matches registered idp cert
  fingerprint             = Digest::SHA1.hexdigest(cert.to_der)
  valid_flag              = fingerprint == idp_cert_fingerprint.gsub(":", "").downcase

  return valid_flag if !valid_flag

  validate_doc(base64_cert, logger)
end

#validate_doc(base64_cert, logger) ⇒ Object 



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# File 'lib/xml_security.rb', line 51

def validate_doc(base64_cert, logger)
  # validate references

  # remove signature node
  sig_element = REXML::XPath.first(self, "//ds:Signature", {"ds"=>"http://www.w3.org/2000/09/xmldsig#"})
  sig_element.remove

  #check digests
  REXML::XPath.each(sig_element, "//ds:Reference", {"ds"=>"http://www.w3.org/2000/09/xmldsig#"}) do | ref |

    uri                   = ref.attributes.get_attribute("URI").value
    hashed_element        = REXML::XPath.first(self, "//[@ID='#{uri[1,uri.size]}']")
    canoner               = XML::Util::XmlCanonicalizer.new(false, true)
    canon_hashed_element  = canoner.canonicalize(hashed_element)
    hash                  = Base64.encode64(Digest::SHA1.digest(canon_hashed_element)).chomp
    digest_value          = REXML::XPath.first(ref, "//ds:DigestValue", {"ds"=>"http://www.w3.org/2000/09/xmldsig#"}).text

    valid_flag            = hash == digest_value

    return valid_flag if !valid_flag
  end

  # verify signature
  canoner                 = XML::Util::XmlCanonicalizer.new(false, true)
  signed_info_element     = REXML::XPath.first(sig_element, "//ds:SignedInfo", {"ds"=>"http://www.w3.org/2000/09/xmldsig#"})
  canon_string            = canoner.canonicalize(signed_info_element)

  base64_signature        = REXML::XPath.first(sig_element, "//ds:SignatureValue", {"ds"=>"http://www.w3.org/2000/09/xmldsig#"}).text
  signature               = Base64.decode64(base64_signature)

  # get certificate object
  cert_text               = Base64.decode64(base64_cert)
  cert                    = OpenSSL::X509::Certificate.new(cert_text)

  valid_flag              = cert.public_key.verify(OpenSSL::Digest::SHA1.new, signature, canon_string)

  return valid_flag
end