Setup gem signing.

Rakefile

@@ -14,3 +14,12 @@ task :default do
   puts "Nothing to do for the default task"
 end
 
+task :verify_private_key_present do
+  private_key = File.expand_path('~/.gem/rspec-gem-private_key.pem')
+  unless File.exists?(private_key)
+    raise "Your private key is not present. This gem should not be built without that."
+  end
+end
+
+task :build => :verify_private_key_present
+

rspec.gemspec

@@ -24,6 +24,12 @@ Gem::Specification.new do |s|
   s.rdoc_options     = ["--charset=UTF-8"]
   s.require_path     = "lib"
 
+  private_key = File.expand_path('~/.gem/rspec-gem-private_key.pem')
+  if File.exists?(private_key)
+    s.signing_key = private_key
+    s.cert_chain = [File.expand_path('~/.gem/rspec-gem-public_cert.pem')]
+  end
+
   %w[core expectations mocks].each do |name|
     if RSpec::Version::STRING =~ /[a-zA-Z]+/
       s.add_runtime_dependency "rspec-#{name}", "= #{RSpec::Version::STRING}"