Create an Encryption Schema

Create a JSON encryption schema document

Include an encryptedFieldsObject with a nested fields array:

const encryptedFieldsObject = {
   fields: []
}

Specify fields to encrypt.

1. Add the path and bsonType strings to the fields array:

   const encryptedFieldsObject = {
      fields: [
         {
            path: "myDocumentField",
            bsonType: "int"
         }
      ]
   }

   Important

   You can specify any field for encryption except the _id field.

2. If you are using explicit encryption, add a keyId field with the DEK

   {
      path: "myDocumentField",
      bsonType: "int",
      keyId: "<unique data encryption key>"
   }

   Tip

   With Automatic Encryption, MongoDB creates encryption keys for each field. You configure AutoEncryptionSettings on the client, then use the createEncryptedCollection helper method to create your collections.

Enable equality queries on desired fields.

This enables querying with the $eq, $ne, $in, and $nin operators.

1. Add the queries object and set queryType to "equality":

   {
      path: "myDocumentField",
      bsonType: "int",
      queries: { queryType: "equality" }
   }

2. (Optional) Set contention to favor either find performance, or write and update performance.

   If unset, this defaults to 8.

   {
      path: "myDocumentField",
      bsonType: "int",
      queries: { queryType: "equality",
                 contention: 8
      }
   }

Enable range queries on desired fields.

This enables querying with the $lt, $lte, $gt, and $gte operators.

For details on how the following options affect security and performance, see Configure Encrypted Fields for Optimal Search and Storage.

1. Add the queries object and set queryType to "range":

   {
      path: "myDocumentRangeField",
      bsonType: "int",
      queries: { queryType: "range" }
   }

2. Set the following fields:

   Field	Type	Description
   sparsity	Integer from 1-4	Optional. Defaults to 2. Affects how thoroughly MongoDB indexes range values. Low sparsity (dense indexing) improves query performance at the cost of storage space.
   min and max	Same as field bsonType	Required if bsonType is decimal or double. Optional but highly recommended if it is int, long, or date. Defaults to the minimum and maximum values of the bsonType. When possible, specifying bounds on a query improves performance. If querying values outside of these inclusive bounds, MongoDB returns an error. This parameter only affects queries. The encrypted value is still stored with full precision.
   precision	Integer	Optional but highly recommended. Allowed only if bsonType is decimal or double. Sets how many digits are taken into account when querying the field.
   trimFactor	Integer	Optional. Defaults to 6. A low trimFactor causes MongoDB to store more documents in the metadata collections for each insert or update operation. This improves insert and update times at the cost of slowing down some range operations . A high trimFactor does the opposite.
   contention	Integer.	Optional. Defaults to 8. Set to favor either find performance, or write and update performance.

   {
      path: "myDocumentRangeField",
      bsonType: "int",
      queries: { queryType: "range",
                 sparsity: 1,
                 min: 0,
                 max: 1200,
                 trimFactor: 1,
                 contention: 7
      }
   }