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#
# 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
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
before_validation :generate, :on => :create
validates :key, :presence => true
validates :cert, :presence => true
design do
end
class << self
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(APP_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(APP_CONFIG[:client_cert_bit_size])
# sign
cert.parent = ClientCertificate.root_ca
cert.sign! client_signing_profile
self.key = cert.key_material.private_key.to_pem
self.cert = cert.to_pem
end
private
def self.root_ca
@root_ca ||= begin
crt = File.read(APP_CONFIG[:ca_cert_path])
key = File.read(APP_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, APP_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" => APP_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
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