add gpg key model

app/models/gpg_key.rb

+class GpgKey < ActiveRecord::Base
+  KEY_PREFIX = '-----BEGIN PGP PUBLIC KEY BLOCK-----'.freeze
+
+  belongs_to :user
+
+  validates :fingerprint,
+    presence: true,
+    uniqueness: true
+
+  validates :key,
+    presence: true,
+    uniqueness: true,
+    format: {
+      with: /\A#{KEY_PREFIX}((?!#{KEY_PREFIX}).)+\Z/m
+    }
+
+  before_validation :extract_fingerprint
+
+  def key=(value)
+    value.strip! unless value.blank?
+    write_attribute(:key, value)
+  end
+
+  private
+
+  def extract_fingerprint
+    import = GPGME::Key.import(key)
+
+    return if import.considered == 0
+
+    # we can assume that the result only contains one item as the validation
+    # only allows one key
+    self.fingerprint = import.imports.first.fingerprint
+  end
+end

db/migrate/20170222111732_create_gpg_keys.rb

+class CreateGpgKeys < ActiveRecord::Migration
+  DOWNTIME = false
+
+  def change
+    create_table :gpg_keys do |t|
+      t.string :fingerprint
+      t.text :key
+      t.references :user, index: true, foreign_key: true
+
+      t.timestamps_with_timezone null: false
+    end
+  end
+end

db/schema.rb

@@ -540,6 +540,16 @@ ActiveRecord::Schema.define(version: 20170725145659) do
 
   add_index "forked_project_links", ["forked_to_project_id"], name: "index_forked_project_links_on_forked_to_project_id", unique: true, using: :btree
 
+  create_table "gpg_keys", force: :cascade do |t|
+    t.string "fingerprint"
+    t.text "key"
+    t.integer "user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  add_index "gpg_keys", ["user_id"], name: "index_gpg_keys_on_user_id", using: :btree
+
   create_table "identities", force: :cascade do |t|
     t.string "extern_uid"
     t.string "provider"
@@ -1602,6 +1612,7 @@ ActiveRecord::Schema.define(version: 20170725145659) do
   add_foreign_key "environments", "projects", name: "fk_d1c8c1da6a", on_delete: :cascade
   add_foreign_key "events", "projects", name: "fk_0434b48643", on_delete: :cascade
   add_foreign_key "forked_project_links", "projects", column: "forked_to_project_id", name: "fk_434510edb0", on_delete: :cascade
+  add_foreign_key "gpg_keys", "users"
   add_foreign_key "issue_assignees", "issues", name: "fk_b7d881734a", on_delete: :cascade
   add_foreign_key "issue_assignees", "users", name: "fk_5e0c8d9154", on_delete: :cascade
   add_foreign_key "issue_metrics", "issues", on_delete: :cascade

spec/models/gpg_key_spec.rb

+require 'rails_helper'
+
+describe GpgKey do
+  describe "associations" do
+    it { is_expected.to belong_to(:user) }
+  end
+
+  describe "validation" do
+    it { is_expected.to validate_presence_of(:fingerprint) }
+
+    it { is_expected.to validate_presence_of(:key) }
+    it { is_expected.to validate_uniqueness_of(:key) }
+    it { is_expected.to allow_value("-----BEGIN PGP PUBLIC KEY BLOCK-----\nkey").for(:key) }
+    it { is_expected.not_to allow_value("-----BEGIN PGP PUBLIC KEY BLOCK-----\nkey\n-----BEGIN PGP PUBLIC KEY BLOCK-----").for(:key) }
+    it { is_expected.not_to allow_value('BEGIN PGP').for(:key) }
+  end
+
+  context 'callbacks' do
+    describe 'extract_fingerprint' do
+      it 'extracts the fingerprint from the gpg key', :gpg do
+        gpg_key = described_class.new(key: GpgHelpers.public_key)
+        gpg_key.valid?
+        expect(gpg_key.fingerprint).to eq '4F4840A503964251CF7D7F5DC728AF10972E97C0'
+      end
+    end
+  end
+
+  describe '#key=' do
+    it 'strips white spaces' do
+      key = <<~KEY.strip
+        -----BEGIN PGP PUBLIC KEY BLOCK-----
+        Version: GnuPG v1
+
+        mQENBFMOSOgBCADFCYxmnXFbrDhfvlf03Q/bQuT+nZu46BFGbo7XkUjDowFXJQhP
+        -----END PGP PUBLIC KEY BLOCK-----
+      KEY
+
+      expect(described_class.new(key: " #{key} ").key).to eq(key)
+    end
+  end
+end