Class: XMLSecurity::SignedDocument

Inherits:
BaseDocument
  • Object
show all
Includes:
OneLogin::RubySaml::ErrorHandling
Defined in:
lib/xml_security.rb

Constant Summary

Constants inherited from BaseDocument

BaseDocument::C14N, BaseDocument::DSIG, BaseDocument::NOKOGIRI_OPTIONS

Instance Attribute Summary collapse

Attributes included from OneLogin::RubySaml::ErrorHandling

#errors

Instance Method Summary collapse

Methods included from OneLogin::RubySaml::ErrorHandling

#append_error, #reset_errors!

Methods inherited from BaseDocument

#algorithm, #canon_algorithm, safe_load_xml

Constructor Details

#initialize(response, errors = []) ⇒ SignedDocument

Returns a new instance of SignedDocument.



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# File 'lib/xml_security.rb', line 216

def initialize(response, errors = [])
  super(response)
  @errors = errors
  reset_elements
end

Instance Attribute Details

#signed_element_id ⇒ Object 



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# File 'lib/xml_security.rb', line 239

def signed_element_id
  @signed_element_id ||= extract_signed_element_id
end

Instance Method Details

#cache_referenced_xml(soft, check_malformed_doc = true) ⇒ Object 



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# File 'lib/xml_security.rb', line 314

def cache_referenced_xml(soft, check_malformed_doc = true)
  reset_elements
  @processed = true

  begin
    nokogiri_document = XMLSecurity::BaseDocument.safe_load_xml(self, check_malformed_doc)
  rescue StandardError => error
    @errors << error.message
    return false if soft
    raise ValidationError.new("XML load failed: #{error.message}")
  end

  # create a rexml document
  @working_copy ||= REXML::Document.new(self.to_s).root

  # get signature node
  sig_element = REXML::XPath.first(
      @working_copy,
      "//ds:Signature",
      {"ds"=>DSIG}
  )

  return if sig_element.nil?

  # signature method
  sig_alg_value = REXML::XPath.first(
    sig_element,
    "./ds:SignedInfo/ds:SignatureMethod",
    {"ds"=>DSIG}
  )
  @signature_algorithm = algorithm(sig_alg_value)

  # get signature
  base64_signature = REXML::XPath.first(
    sig_element,
    "./ds:SignatureValue",
    {"ds" => DSIG}
  )

  return if base64_signature.nil?

  base64_signature_text = OneLogin::RubySaml::Utils.element_text(base64_signature)
  @signature = base64_signature_text.nil? ? nil : Base64.decode64(base64_signature_text)

  # canonicalization method
  canon_algorithm = canon_algorithm REXML::XPath.first(
    sig_element,
    './ds:SignedInfo/ds:CanonicalizationMethod',
    'ds' => DSIG
  )

  noko_sig_element = nokogiri_document.at_xpath('//ds:Signature', 'ds' => DSIG)
  noko_signed_info_element = noko_sig_element.at_xpath('./ds:SignedInfo', 'ds' => DSIG)

  @cached_signed_info = noko_signed_info_element.canonicalize(canon_algorithm)

  ### Now get the @referenced_xml to use?
  rexml_signed_info = REXML::Document.new(@cached_signed_info.to_s).root

  noko_sig_element.remove

  # get inclusive namespaces
  inclusive_namespaces = extract_inclusive_namespaces

  # check digests
  @ref = REXML::XPath.first(rexml_signed_info, "./ds:Reference", {"ds"=>DSIG})
  return if @ref.nil?

  reference_nodes = nokogiri_document.xpath("//*[@ID=$id]", nil, { 'id' => extract_signed_element_id })

  hashed_element = reference_nodes[0]
  return if hashed_element.nil?

  canon_algorithm = canon_algorithm REXML::XPath.first(
    rexml_signed_info,
    './ds:CanonicalizationMethod',
    { "ds" => DSIG }
  )

  canon_algorithm = process_transforms(@ref, canon_algorithm)

  @referenced_xml = hashed_element.canonicalize(canon_algorithm, inclusive_namespaces)
end

#processed ⇒ Object 



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# File 'lib/xml_security.rb', line 231

def processed
  @processed
end

#referenced_xml ⇒ Object 



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# File 'lib/xml_security.rb', line 235

def referenced_xml
  @referenced_xml
end

#reset_elements ⇒ Object 



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# File 'lib/xml_security.rb', line 222

def reset_elements
  @referenced_xml = nil
  @cached_signed_info = nil
  @signature = nil
  @signature_algorithm = nil
  @ref = nil
  @processed = false
end

#validate_document(idp_cert_fingerprint, soft = true, options = {}) ⇒ Object

Validates the referenced_xml, which is the signed part of the document



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# File 'lib/xml_security.rb', line 244

def validate_document(idp_cert_fingerprint, soft = true, options = {})
  # get cert from response
  cert_element = REXML::XPath.first(
    self,
    "//ds:X509Certificate",
    { "ds"=>DSIG }
  )

  if cert_element
    base64_cert = OneLogin::RubySaml::Utils.element_text(cert_element)
    cert_text = Base64.decode64(base64_cert)
    begin
      cert = OpenSSL::X509::Certificate.new(cert_text)
    rescue OpenSSL::X509::CertificateError => _e
      return append_error("Document Certificate Error", soft)
    end

    if options[:fingerprint_alg]
      fingerprint_alg = XMLSecurity::BaseDocument.new.algorithm(options[:fingerprint_alg]).new
    else
      fingerprint_alg = OpenSSL::Digest.new('SHA1')
    end
    fingerprint = fingerprint_alg.hexdigest(cert.to_der)

    # check cert matches registered idp cert
    if fingerprint != idp_cert_fingerprint.gsub(/[^a-zA-Z0-9]/,"").downcase
      return append_error("Fingerprint mismatch", soft)
    end
    base64_cert = Base64.encode64(cert.to_der)
  else
    if options[:cert]
      base64_cert = Base64.encode64(options[:cert].to_pem)
    else
      if soft
        return false
      else
        return append_error("Certificate element missing in response (ds:X509Certificate) and not cert provided at settings", soft)
      end
    end
  end
  validate_signature(base64_cert, soft)
end

#validate_document_with_cert(idp_cert, soft = true) ⇒ Object 



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# File 'lib/xml_security.rb', line 287

def validate_document_with_cert(idp_cert, soft = true)
  # get cert from response
  cert_element = REXML::XPath.first(
    self,
    "//ds:X509Certificate",
    { "ds"=>DSIG }
  )

  if cert_element
    base64_cert = OneLogin::RubySaml::Utils.element_text(cert_element)
    cert_text = Base64.decode64(base64_cert)
    begin
      cert = OpenSSL::X509::Certificate.new(cert_text)
    rescue OpenSSL::X509::CertificateError => _e
      return append_error("Document Certificate Error", soft)
    end

    # check saml response cert matches provided idp cert
    if idp_cert.to_pem != cert.to_pem
      return append_error("Certificate of the Signature element does not match provided certificate", soft)
    end
  end

  encoded_idp_cert = Base64.encode64(idp_cert.to_pem)
  validate_signature(encoded_idp_cert, true)
end

#validate_signature(base64_cert, soft = true) ⇒ Object 



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# File 'lib/xml_security.rb', line 398

def validate_signature(base64_cert, soft = true)
  if !@processed
    cache_referenced_xml(soft)
  end

  return append_error("No Signature Algorithm Method found", soft) if @signature_algorithm.nil?  
  return append_error("No Signature node found", soft) if @signature.nil?  
  return append_error("No canonized SignedInfo ", soft) if @cached_signed_info.nil?
  return append_error("No Reference node found", soft) if @ref.nil?
  return append_error("No referenced XML", soft) if @referenced_xml.nil?

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

  digest_algorithm = algorithm(REXML::XPath.first(
    @ref,
    "./ds:DigestMethod",
    { "ds" => DSIG }
  ))
  hash = digest_algorithm.digest(@referenced_xml)
  encoded_digest_value = REXML::XPath.first(
    @ref,
    "./ds:DigestValue",
    { "ds" => DSIG }
  )
  encoded_digest_value_text = OneLogin::RubySaml::Utils.element_text(encoded_digest_value)
  digest_value = encoded_digest_value_text.nil? ? nil : Base64.decode64(encoded_digest_value_text)

  # Compare the computed "hash" with the "signed" hash
  unless hash && hash == digest_value
    return append_error("Digest mismatch", soft)
  end

  # verify signature
  unless cert.public_key.verify(@signature_algorithm.new, @signature, @cached_signed_info)
    return append_error("Key validation error", soft)
  end

  return true
end