Works giving all grants.

node_access_link.info

+name = Node access link
+description = Generates link for view, edit, or delete node without login.
+dependencies[] = computed_field
+core = 7.x
+files[] = node_access_link.module
\ No newline at end of file

node_access_link.module

+<?php
+// $Id$
+
+/**
+ * @file
+ * TODO: Enter file description here.
+ */
+
+/**
+ * Alter of node_type_form.
+ */
+function node_access_link_form_node_type_form_alter(&$form, &$form_state) {
+  $form['node_access_link'] = array(
+    '#type' => 'fieldset',
+    '#title' => t('Node Auth Key'),
+    '#collapsible' => TRUE,
+    '#collapsed' => TRUE,
+    '#group' => 'additional_settings',
+  );
+  
+  $instance = field_info_instance('node', 'field_node_access_link_authkey', $form['#node_type']->type);
+  
+  $form['node_access_link']['node_access_link_enable'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Enable'),
+    '#default_value' => (bool)$instance,
+    '#description' => t('Disable of this feature will cost erase of authorization keys of all nodes in this node type.'),
+  );
+  
+  if(is_array($instance) && isset($instance['node_access_link_grants']))
+    $default_grants = array_keys($instance['node_access_link_grants'], TRUE);
+  else
+    $default_grants = array();
+  
+  $form['node_access_link']['node_access_link_grants'] = array(
+    '#type' => 'checkboxes', 
+    '#title' => t('Grants'), 
+    '#default_value' => $default_grants,
+    '#options' => array(
+      'view' => t('View'),
+      'update' => t('Update'), 
+      'delete' => t('Delete'), 
+    ),
+    '#description' => t('What operations will be temporarily given to authorised user for the node.'),
+  );
+  
+  $form['#submit'][] = 'node_access_link_form_node_type_form_alter_submit';
+}
+
+/**
+ * Submit for node_type_form.
+ */
+function node_access_link_form_node_type_form_alter_submit(&$form, &$form_state) {
+  $instance = field_info_instance('node', 'field_node_access_link_authkey', $form_state['values']['type']);
+  
+  if(!$instance && $form_state['values']['node_access_link_enable']) { // Instance does not exist and checkbox is enabled
+    node_access_link_create_field_instance($form_state['values']['type']);
+  }
+  
+  elseif($instance && !$form_state['values']['node_access_link_enable']) { // Instance exists and checkbox is disabled
+    field_delete_instance($instance);
+  }
+  
+  
+}
+
+/**
+ * Create field instance in specified node type.
+ */
+function node_access_link_create_field_instance($node_type) {
+  if(!field_info_field('field_node_access_link_authkey')) {
+    $field = array(
+      'translatable' => '1',
+      'settings' => array(
+        'code' => '',
+        'display_format' => '$display_output = $entity_field_item[\'value\'];',
+        'store' => 1,
+        'database' => array(
+          'data_type' => 'varchar',
+          'data_length' => '64',
+          'data_size' => 'normal',
+          'data_precision' => '10',
+          'data_scale' => '2',
+          'data_default' => '',
+          'data_not_NULL' => 1,
+          'data_index' => 0,
+        ),
+      ),
+      'field_name' => 'field_node_access_link_authkey',
+      'type' => 'computed',
+      'active' => '1',
+      'locked' => '0',
+      'cardinality' => '1',
+    );
+    field_create_field($field);
+  }
+  
+  $instance = array(
+    'label' => 'Node access link',
+    'widget' => array(
+      'type' => 'computed',
+      'weight' => '1',
+      'settings' => array(),
+    ),
+    'settings' => array(
+      'user_register_form' => FALSE,
+    ),
+    'display' => array(
+      'default' => array(
+        'label' => 'above',
+        'type' => 'hidden',
+        'weight' => '12',
+        'settings' => array(),
+      ),
+      'teaser' => array(
+        'type' => 'hidden',
+        'label' => 'above',
+        'settings' => array(),
+        'weight' => 0,
+      ),
+    ),
+    'required' => FALSE,
+    'description' => '',
+    'field_name' => 'field_node_access_link_authkey',
+    'entity_type' => 'node',
+    'bundle' => $node_type,
+  );
+  field_create_instance($instance);
+}
+
+/**
+ * Implementation of hook_node_access().
+ */
+function node_access_link_node_access($node, $op, $account) {
+  // Ignore if just creating node
+  if($op == 'create')
+    return NODE_ACCESS_IGNORE;
+  
+  // Check key
+  if(isset($_GET['authkey']) && isset($node->field_node_access_link_authkey)) {
+    $authkeys = field_get_items('node', $node, 'field_node_access_link_authkey');
+    if($authkeys[0]['value'] == $_GET['authkey']) {
+      // Start session
+      if(!isset($_SESSION))
+        drupal_session_initialize();
+      // Save authorization to session
+      $_SESSION['node_access_link_auth_nodes'][$node->nid] = TRUE;
+    }
+  }
+  
+  // Permit if checked
+  if(isset($_SESSION['node_access_link_auth_nodes'][$node->nid]))
+    return NODE_ACCESS_ALLOW;
+}
+
+/**
+ * Computed field callback which generate auth key.
+ */
+function computed_field_field_node_access_link_authkey_compute(&$entity_field, $entity_type, $entity, $field, $instance, $langcode, $items) {
+  
+  // Break if set yet and entity is not node
+  if(!empty($entity_field[0]['value']) || $entity_type != 'node')
+    return;
+  
+  // Find key in other languages
+  foreach($entity->field_node_access_link_authkey as $values) {
+    if(!empty($values[0]['value'])) {
+      $actual = $values[0]['value'];
+      break;
+    }
+  }
+  
+  // Generate new key
+  if(!isset($actual))
+    $actual = hash('sha256', drupal_random_bytes(64));
+  
+  $entity_field[0]['value'] = $actual;
+}
+
+/**
+ * Get edit URL of specified node.
+ * @param $node Node object or NID.
+ */
+function node_access_link_get_url($node) {
+  if(is_numeric($node))
+    $node = node_load($node);
+    
+  $items = field_get_items('node', $node, 'field_node_access_link_authkey');
+  if(!$items)
+    return FALSE;
+  
+  return url("node/$node->nid/edit", array(
+    'absolute' => TRUE,
+    'query' => array('authkey' => $items[0]['value']),
+  ));
+}
+