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

Constructor Details

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

Returns a new instance of SignedDocument.



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# File 'lib/xml_security.rb', line 190

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

Instance Attribute Details

#signed_element_id ⇒ Object 



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# File 'lib/xml_security.rb', line 195

def signed_element_id
  @signed_element_id ||= extract_signed_element_id
end

Instance Method Details

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



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# File 'lib/xml_security.rb', line 199

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
  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 241

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
  else
    base64_cert = Base64.encode64(idp_cert.to_pem)
  end
  validate_signature(base64_cert, true)
end

#validate_signature(base64_cert, soft = true) ⇒ Object 



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# File 'lib/xml_security.rb', line 268

def validate_signature(base64_cert, soft = true)

  document = Nokogiri::XML(self.to_s) do |config|
    config.options = XMLSecurity::BaseDocument::NOKOGIRI_OPTIONS
  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}
  )

  # 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}
  )
  signature = Base64.decode64(OneLogin::RubySaml::Utils.element_text(base64_signature))

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

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

  canon_string = noko_signed_info_element.canonicalize(canon_algorithm)
  noko_sig_element.remove

  # get signed info
  signed_info_element = REXML::XPath.first(
    sig_element,
    "./ds:SignedInfo",
    { "ds" => DSIG }
  )

  # get inclusive namespaces
  inclusive_namespaces = extract_inclusive_namespaces

  # check digests
  ref = REXML::XPath.first(signed_info_element, "./ds:Reference", {"ds"=>DSIG})

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

  if reference_nodes.length > 1 # ensures no elements with same ID to prevent signature wrapping attack.
    return append_error("Digest mismatch. Duplicated ID found", soft)
  end

  hashed_element = reference_nodes[0]

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

  canon_algorithm = process_transforms(ref, canon_algorithm)

  canon_hashed_element = hashed_element.canonicalize(canon_algorithm, inclusive_namespaces)

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

  unless digests_match?(hash, digest_value)
    return append_error("Digest mismatch", soft)
  end

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

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

  return true
end