Add login via nostr (web extension)

app/assets/stylesheets/components/buttons.css

@@ -42,6 +42,11 @@
            focus:ring-red-500 focus:ring-opacity-75;
   }
 
+  .btn-outline-purple {
+    @apply border-2 border-purple-500 hover:bg-purple-100
+           focus:ring-purple-400 focus:ring-opacity-75;
+  }
+
   .btn:disabled {
     @apply bg-gray-100 hover:bg-gray-200 text-gray-400
            focus:ring-gray-300 focus:ring-opacity-75;

app/controllers/users/sessions_controller.rb

@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+class Users::SessionsController < Devise::SessionsController
+  # before_action :configure_sign_in_params, only: [:create]
+
+  # GET /resource/sign_in
+  def new
+    session[:shared_secret] = SecureRandom.base64(12)
+    super
+  end
+
+  # POST /resource/sign_in
+  # def create
+  #   super
+  # end
+
+  # DELETE /resource/sign_out
+  # def destroy
+  #   super
+  # end
+
+  # POST /users/nostr_login
+  def nostr_login
+    signed_event = Nostr::Event.new(**nostr_event_from_params)
+
+    is_valid_sig  = signed_event.verify_signature
+    is_valid_auth = NostrManager::VerifyAuth.call(
+      event: signed_event,
+      challenge: session[:shared_secret]
+    )
+
+    session[:shared_secret] = nil
+
+    unless is_valid_sig && is_valid_auth
+      flash[:alert] = "Login verification failed"
+      http_status :unauthorized and return
+    end
+
+    user = LdapManager::FetchUserByNostrKey.call(pubkey: signed_event.pubkey)
+
+    if user.present?
+      set_flash_message!(:notice, :signed_in)
+      sign_in("user", user)
+      render json: { redirect_url: after_sign_in_path_for(user) }, status: :ok
+    else
+      flash[:alert] = "Failed to find your account. Nostr login may be disabled."
+      http_status :unauthorized
+    end
+  end
+
+  protected
+
+    def set_flash_message(key, kind, options = {})
+      # Hide flash message after redirecting from a signin route while logged in
+      super unless key == :alert && kind == "already_authenticated"
+    end
+
+  # If you have extra params to permit, append them to the sanitizer.
+  # def configure_sign_in_params
+  #   devise_parameter_sanitizer.permit(:sign_in, keys: [:attribute])
+  # end
+end

app/javascript/controllers/nostr_login_controller.js

@@ -0,0 +1,53 @@
+import { Controller } from "@hotwired/stimulus"
+
+// Connects to data-controller="nostr-login"
+export default class extends Controller {
+  static targets = [ "loginForm", "loginButton" ]
+  static values  = { site: String, sharedSecret: String }
+
+  connect() {
+    if (window.nostr) {
+      this.loginButtonTarget.disabled = false
+      this.loginFormTarget.classList.remove("hidden")
+    }
+  }
+
+  async login () {
+    this.loginButtonTarget.disabled = true
+
+    try {
+      // Auth based on NIP-42
+      const signedEvent = await window.nostr.signEvent({
+        created_at: Math.floor(Date.now() / 1000),
+        kind: 22242,
+        tags: [
+          ["site", this.siteValue],
+          ["challenge", this.sharedSecretValue]
+        ],
+        content: ""
+      })
+
+      const res = await fetch("/users/nostr_login", {
+        method: "POST", credentials: "include", headers: {
+          "Accept": "application/json", 'Content-Type': 'application/json',
+          "X-CSRF-Token": this.csrfToken
+        }, body: JSON.stringify({ signed_event: signedEvent })
+      })
+
+      if (res.status === 200) {
+        res.json().then(r => { window.location.href = r.redirect_url })
+      } else {
+        window.location.reload()
+      }
+    } catch (error) {
+      console.warn('Unable to authenticate:', error.message)
+    } finally {
+      this.loginButtonTarget.disabled = false
+    }
+  }
+
+  get csrfToken () {
+    const element = document.head.querySelector('meta[name="csrf-token"]')
+    return element.getAttribute("content")
+  }
+}

app/views/devise/sessions/new.html.erb

@@ -55,4 +55,27 @@
       <%= f.submit "Log in", class: 'btn-md btn-blue w-full', tabindex: "4" %>
     </p>
   <% end %>
+
+  <div data-controller="nostr-login"
+       data-nostr-login-target="loginForm"
+       data-nostr-login-site-value="<%= Setting.accounts_domain %>"
+       data-nostr-login-shared-secret-value="<%= session[:shared_secret] %>"
+       class="hidden">
+    <div class="relative my-6">
+      <div class="absolute inset-0 flex items-center" aria-hidden="true">
+        <div class="w-full border-t border-gray-200"></div>
+      </div>
+      <div class="relative flex justify-center">
+        <span class="bg-white px-2 text-sm text-gray-500 italic">or</span>
+      </div>
+    </div>
+    <p>
+      <button disabled tabindex="5"
+              class="w-full btn-md btn-gray text-purple-600"
+              data-nostr-login-target="loginButton"
+              data-action="nostr-login#login">
+        Log in with Nostr
+      </button>
+    </p>
+  </div>
 <% end %>