Add E2EE API (#13820)

app/models/one_time_key.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: one_time_keys
+#
+#  id         :bigint(8)        not null, primary key
+#  device_id  :bigint(8)
+#  key_id     :string           default(""), not null
+#  key        :text             default(""), not null
+#  signature  :text             default(""), not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+
+class OneTimeKey < ApplicationRecord
+  belongs_to :device
+
+  validates :key_id, :key, :signature, presence: true
+  validates :key, ed25519_key: true
+  validates :signature, ed25519_signature: { message: :key, verify_key: ->(one_time_key) { one_time_key.device.fingerprint_key } }
+end