1 files changed, 148 insertions, 0 deletions
diff --git a/certs/app/models/client_certificate.rb b/certs/app/models/client_certificate.rb
new file mode 100644
index 0000000..23b66a2
--- /dev/null
+++ b/certs/app/models/client_certificate.rb
@@ -0,0 +1,148 @@
+#
+# Model for certificates stored in CouchDB.
+#
+# This file must be loaded after Config has been loaded.
+#
+require 'base64'
+require 'digest/md5'
+require 'openssl'
+require 'certificate_authority'
+require 'date'
+
+class ClientCertificate < CouchRest::Model::Base
+
+  # No config yet.    use_database LeapCA::Config.db_name
+  use_database 'client_certificates'
+
+  timestamps!
+
+  property :key, String                          # the client private RSA key
+  property :cert, String                         # the client x509 certificate, signed by the CA
+  property :valid_until, Time                    # expiration time of the client certificate
+  property :random, Float, :accessible => false  # used to help pick a random cert by the webapp
+
+  before_validation :generate, :set_random, :on => :create
+
+  validates :key, :presence => true
+  validates :cert, :presence => true
+  validates :random, :presence => true
+  validates :random, :numericality => {:greater_than => 0, :less_than => 1}
+
+  design do
+    view :by_random
+  end
+
+  class << self
+    def sample
+      self.by_random.startkey(rand).first || self.by_random.first
+    end
+
+    def pick_from_pool
+      cert = self.sample
+      raise RECORD_NOT_FOUND unless cert
+      cert.destroy
+      return cert
+    rescue RESOURCE_NOT_FOUND
+      retry if self.by_random.count > 0
+      raise RECORD_NOT_FOUND
+    end
+
+    def valid_attributes_hash
+      {:key => "ABCD", :cert => "A123"}
+    end
+  end
+
+  #
+  # generate the private key and client certificate
+  #
+  def generate
+    cert = CertificateAuthority::Certificate.new
+
+    # set subject
+    cert.subject.common_name = random_common_name
+
+    # set expiration
+    self.valid_until = months_from_yesterday(Config.client_cert_lifespan)
+    cert.not_before = yesterday
+    cert.not_after = self.valid_until
+
+    # generate key
+    cert.serial_number.number = cert_serial_number
+    cert.key_material.generate_key(Config.client_cert_bit_size)
+
+    # sign
+    cert.parent = Cert.root_ca
+    cert.sign! client_signing_profile
+
+    self.key = cert.key_material.private_key.to_pem
+    self.cert = cert.to_pem
+  end
+
+  private
+
+  def set_random
+    self.random = rand
+  end
+
+  def self.root_ca
+    @root_ca ||= begin
+                   crt = File.read(Config.ca_cert_path)
+                   key = File.read(Config.ca_key_path)
+                   openssl_cert = OpenSSL::X509::Certificate.new(crt)
+                   cert = CertificateAuthority::Certificate.from_openssl(openssl_cert)
+                   cert.key_material.private_key = OpenSSL::PKey::RSA.new(key, Config.ca_key_password)
+                   cert
+                 end
+  end
+
+  #
+  # For cert serial numbers, we need a non-colliding number less than 160 bits.
+  # md5 will do nicely, since there is no need for a secure hash, just a short one.
+  # (md5 is 128 bits)
+  #
+  def cert_serial_number
+    Digest::MD5.hexdigest("#{rand(10**10)} -- #{Time.now}").to_i(16)
+  end
+
+  #
+  # for the random common name, we need a text string that will be unique across all certs.
+  # ruby 1.8 doesn't have a built-in uuid generator, or we would use SecureRandom.uuid
+  #
+  def random_common_name
+    cert_serial_number.to_s(36)
+  end
+
+  def client_signing_profile
+    {
+      "digest" => Config.client_cert_hash,
+      "extensions" => {
+      "keyUsage" => {
+      "usage" => ["digitalSignature"]
+    },
+      "extendedKeyUsage" => {
+      "usage" => ["clientAuth"]
+    }
+    }
+    }
+  end
+
+  ##
+  ## TIME HELPERS
+  ##
+  ## note: we use 'yesterday' instead of 'today', because times are in UTC, and some people on the planet
+  ## are behind UTC.
+  ##
+
+  def yesterday
+    t = Time.now - 24*24*60
+    Time.utc t.year, t.month, t.day
+  end
+
+  def months_from_yesterday(num)
+    t = yesterday
+    date = Date.new t.year, t.month, t.day
+    date = date >> num # >> is months in the future operator
+    Time.utc date.year, date.month, date.day
+  end
+
+end