Class: OmniAuth::Strategies::SAML::XMLSecurity::SignedDocument

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

Constant Summary collapse

DSIG = 
"http://www.w3.org/2000/09/xmldsig#"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(response) ⇒ SignedDocument

Returns a new instance of SignedDocument.



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# File 'lib/omniauth/strategies/saml/xml_security.rb', line 43

def initialize(response)
  super(response)
  extract_signed_element_id
end

Instance Attribute Details

#signed_element_id ⇒ Object

Returns the value of attribute signed_element_id.



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# File 'lib/omniauth/strategies/saml/xml_security.rb', line 41

def signed_element_id
  @signed_element_id
end

Instance Method Details

#validate(idp_cert_fingerprint, soft = true) ⇒ Object 



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# File 'lib/omniauth/strategies/saml/xml_security.rb', line 48

def validate(idp_cert_fingerprint, soft = true)
  # 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)

  if fingerprint != idp_cert_fingerprint.gsub(/[^a-zA-Z0-9]/,"").downcase
    return soft ? false : (raise OmniAuth::Strategies::SAML::ValidationError.new("Fingerprint mismatch"))
  end

  validate_doc(base64_cert, soft)
end

#validate_doc(base64_cert, soft = true) ⇒ Object 



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# File 'lib/omniauth/strategies/saml/xml_security.rb', line 64

def validate_doc(base64_cert, soft = true)
  # validate references

  # check for inclusive namespaces

  inclusive_namespaces            = []
  inclusive_namespace_element     = REXML::XPath.first(self, "//ec:InclusiveNamespaces")

  if inclusive_namespace_element
    prefix_list                   = inclusive_namespace_element.attributes.get_attribute('PrefixList').value
    inclusive_namespaces          = prefix_list.split(" ")
  end

  # 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)
    canoner.inclusive_namespaces  = inclusive_namespaces if canoner.respond_to?(:inclusive_namespaces) && !inclusive_namespaces.empty?
    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

    if hash != digest_value
      return soft ? false : (raise OmniAuth::Strategies::SAML::ValidationError.new("Digest mismatch"))
    end
  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)

  if !cert.public_key.verify(OpenSSL::Digest::SHA1.new, signature, canon_string)
    return soft ? false : (raise OmniAuth::Strategies::SAML::ValidationError.new("Key validation error"))
  end

  return true
end