Add ssh key validation

app/models/key.rb

@@ -10,6 +10,7 @@ class Key < ActiveRecord::Base
 
   validates :key,
             presence: true,
+            :format => { :with => /ssh-.{3} / },
             length: { within: 0..5000 }
 
   before_save :set_identifier

spec/factories.rb

@@ -77,7 +77,7 @@ FactoryGirl.define do
     title
     key do
       """
-      AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt4
+      ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt4
       596k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qkr8prgHc4
       soW6NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMgJw0=
       """