Using my forks of Akami and Savon to sign a request with a X.509 certificate. See https://github.com/genuitytech/akami and https://github.com/genuitytech/savon.

savon_client.rb

client = Savon::Client.new do
  # This can be a URL also
  wsdl.document = "/Path/to/your.wsdl"

  # These are optional, only if your WSDL sucks :)
  wsdl.endpoint = "https://your_endpoint"
  wsdl.namespace = "http://your_namespace"

  certs = Akami::WSSE::Certs.new :cert_file => "/path/to/cert.crt", :private_key_file => "/path/to/private/key.pem", :private_key_password => "password"
  wsse.sign_with = Akami::WSSE::Signature.new certs

  # SSL certs, if you need them
  http.auth.ssl.tap do |ssl|
    ssl.cert_file = "/path/to/signing/cert.crt"
    ssl.cert_key_file = "/path/to/signing/private.key"
    ssl.cert_key_password = "password"
    ssl.ca_cert_file = "/path/to/signing/ca.crt"
  end
end

# soap_action is optional
res = client.request :namespace_identifier, :element, soap_action: :action do
  soap.element_form_default = :qualified
  soap.body = {
    element1: 'foo',
    element2: 'bar'
  }
end