Using Fortanix Data Security Manager for MongoDB Encryption at Rest

Last Updated: August 31, 2021 14:23

Overview

MongoDB Enterprise version supports the encryption of data at rest. The data encryption process involves generating a master key which is the root of the key hierarchy of various keys used by MongoDB.

Cryptographically secure generation and secure management of this master key are required for the true security of data at rest encrypted by MongoDB. Fortanix Data Security Manager with its KMIP support provides a secure and flexible solution for this.

MongoDB supports KMIP and it authenticates to a KMIP enabled key management server using a client certificate. Fortanix Data Security Manager (DSM) supports clients/apps to authenticate using API Key, App Id, and certificate or just certificate. In this article, we will describe how to set up an app in Fortanix DSM for MongoDB to integrate with Fortanix DSM.

Adding App in Fortanix Data Security Manager

Start by adding an App in Fortanix DSM in an appropriate group or a new group. For instructions on how to add a group or app please use Getting Started Guide

Once you have added the application, note down its App-Id by copying App UUID from the App table view by clicking the icon for “Copy UUID” as shown below. You will need this App-Id for the certificate.

Figure 1: Copy UUID

If an App / Client needs to authenticate to Fortanix DSM using the only certificate, then the App Id needs to be embedded in the certificate in one of the following ways:

Provided as the value of a custom OID in certificate 1.3.6.1.4.1.49690.1.2.1

Standard human-readable UUID encoding: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

Provided as the value of CN

We will explain how to generate a client certificate to use with MongoDB for each of these methods.

Creating a client certificate with custom OID value

You can generate a self-signed certificate such that the custom OID is part of the certificate. To achieve this edit the file /etc/ssl/openssl.cnf and add the custom oid in “new_oids” section. These sections in the file should look as follows

oid_section             = new_oids

# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions            = 
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)

[ new_oids ]
my_app_id=1.3.6.1.4.1.49690.1.2.1

Now add a description in “req_distinguished_name” section. In this section add a line as follows

my_app_id = custom attribute for app id

Save the file and generate a self-signed certificate as shown below:

Change directory to SDKMS_Certs and run the following command.
```
openssl req -newkey rsa:2048 -nodes -keyout private.key -x509 -days 365 -out certificate.crt
```
Figure 2: Create self-signed certificate
Figure 3: Certificate generated
Provide a combined client private key and client certificate when passing the client certificate file to the mongod command. An example of how to combine both the client private key and client certificate, validating the combined client certificate file is shown below:
Figure 4: Example to combine client private key and client certificate

This will prompt for the value of custom attribute where you should enter the App Id you noted earlier.

Generated certificate will have the value of custom OID populated.

Examine the subject in the certificate to verify it contains the custom OID. A correctly generated certificate should look as follows (note the value of custom OID in the subject)

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 18122652583846371291 (0xfb809881cffa5fdb)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, ST=California, L=Mountain View, O=Fortanix Inc, OU=Engineering, CN=test.kmip.fortanix.com/emailAddress=test@fortanix.com/1.3.6.1.4.1.49690.1.2.1=acc15bf3-e626-47aa-9373-7b08b3f26ee8
        Validity
            Not Before: Aug  8 23:19:45 2018 GMT
            Not After : Aug  8 23:19:45 2019 GMT
        Subject: C=US, ST=California, L=Mountain View, O=Fortanix Inc, OU=Engineering, CN=test.kmip.fortanix.com/emailAddress=test@fortanix.com/1.3.6.1.4.1.49690.1.2.1=acc15bf3-e626-47aa-9373-7b08b3f26ee8
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:97:a4:5b:d4:11:ee:c6:89:e1:f8:44:39:f9:69:
                    43:be:ee:69:78:5b:32:26:53:9d:a7:46:f4:17:0e:
                    5a:dc:b4:58:23:af:69:a1:86:de:2e:c5:46:14:98:
                    b6:6a:fc:f5:26:73:f7:56:6f:60:d8:2c:52:69:c9:
                    58:2a:d6:fd:4e:6e:22:0d:8c:e5:99:01:10:70:59:
                    6c:68:a2:a8:ee:e6:37:f7:08:8a:8a:75:bb:91:2b:
                    db:ad:1c:03:56:5f:01:ae:55:ff:3a:8b:40:91:e7:
                    04:4d:49:31:76:dc:ec:9e:d5:cb:d5:73:00:4f:13:
                    f2:12:f3:45:9f:df:fc:aa:2d:5f:d4:95:b2:e9:fa:
                    ad:38:d8:36:a5:f3:99:92:e5:b4:0a:39:99:85:ee:
                    13:39:fb:8d:1c:7a:52:03:e3:86:8a:d8:24:e9:28:
                    70:18:72:e0:b5:e6:f2:66:6f:1c:1a:be:f7:23:2c:
                    e0:9f:79:2b:2e:6e:be:c6:b1:31:65:00:cb:9c:8b:
                    bd:c0:56:dc:bd:0c:24:6a:d2:20:91:5f:14:84:63:
                    ef:18:b2:de:33:a8:ec:dd:4e:a5:3f:11:7b:7d:eb:
                    a1:e1:49:fc:d7:9e:26:98:6f:cb:3b:7e:5d:7e:2d:
                    1e:34:ca:3a:f9:12:95:b2:aa:ff:40:95:e1:5e:b9:
                    a5:a3
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier: 
                9C:74:2E:5B:16:76:F9:59:9F:E0:B5:53:C9:26:45:45:F7:4C:8D:99
            X509v3 Authority Key Identifier: 
                keyid:9C:74:2E:5B:16:76:F9:59:9F:E0:B5:53:C9:26:45:45:F7:4C:8D:99

            X509v3 Basic Constraints: 
                CA:TRUE
    Signature Algorithm: sha256WithRSAEncryption
         72:95:6a:8a:4c:18:53:e9:f6:3d:87:e9:97:d2:48:fe:2b:60:
         ea:e2:ca:81:cb:9b:15:48:38:30:62:16:6b:b0:54:f6:91:2d:
         b0:72:af:36:36:39:8e:78:1f:8c:17:19:df:5c:e5:ae:4d:f4:
         ae:41:39:04:f2:95:d1:0a:99:ef:ef:63:72:5e:83:96:c1:c7:
         f1:d7:f6:45:58:23:76:3d:1a:ba:a3:08:e4:4a:a0:6a:33:8f:
         e5:50:04:b1:08:74:b3:37:9c:fd:f9:9c:5d:27:7d:63:a8:7d:
         40:3e:d5:aa:7d:a7:9e:70:79:38:91:45:68:29:0d:a8:80:42:
         f8:9b:e0:17:bb:93:9f:71:89:04:0f:39:d0:2e:3c:10:62:44:
         6b:41:5d:e5:78:42:50:c5:f7:ee:bc:a8:5e:90:01:ad:3c:f2:
         27:f2:81:16:ba:1e:79:d8:c4:09:cb:01:fd:71:11:9f:91:14:
         72:71:0f:f1:d3:b0:4d:91:78:dd:12:fb:fd:d6:22:93:15:67:
         df:4e:da:df:74:de:68:95:d7:d8:70:48:e2:5f:bc:ec:b2:0f:
         bb:14:83:ad:c9:f9:a0:81:0d:a8:68:64:77:db:5a:71:4a:8b:
         8f:91:d6:ce:e1:33:42:ba:98:76:a1:cd:89:8e:3a:cb:aa:b1:
         8e:ca:42:af

Creating a client certificate with App Id as CN

You can generate a self-signed certificate such that the CN contains the App Id.

Generate a self-signed certificate as shown in the 'Creating a client certificate with custom OID value' section. When prompted for Common Name, you should enter the App Id you noted earlier.

Generated certificate will have App Id as CN.

Examine the subject in the certificate to verify it contains the App Id as CN. A correctly generated certificate should look as follows (note the value of CN)

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 11285796284824083476 (0x9c9f33ed245cdc14)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, ST=CA, L=Mountain View, O=Fortanix, OU=Test, CN=da7f2800-4122-4681-aebf-90beb779b73f/emailAddress=test@fortanix.com
        Validity
            Not Before: Aug  8 23:31:20 2018 GMT
            Not After : Aug  8 23:31:20 2019 GMT
        Subject: C=US, ST=CA, L=Mountain View, O=Fortanix, OU=Test, CN=da7f2800-4122-4681-aebf-90beb779b73f/emailAddress=test@fortanix.com
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:d2:ae:15:66:bf:78:d4:98:f4:4d:a5:57:bf:04:
                    08:76:83:1f:40:e8:8b:c4:da:8a:a0:71:22:43:84:
                    6d:c9:05:f2:81:91:83:04:75:bd:c9:83:86:92:bf:
                    ff:a0:e4:b4:e4:ee:56:09:10:2a:dc:e2:f4:0c:65:
                    43:96:a1:31:0d:15:92:49:87:ee:46:91:5d:f1:8c:
                    61:b3:ca:4a:9f:be:01:00:d5:30:5f:ee:56:35:75:
                    3c:e1:0d:a6:34:66:7f:3b:26:69:97:33:6d:2e:c7:
                    fd:c9:42:7d:14:f7:12:18:4a:5b:a6:90:52:7a:4b:
                    1b:45:b3:79:33:31:99:03:1d:a4:ed:51:dc:7b:43:
                    20:02:bb:08:22:27:27:8c:51:6a:5f:59:87:45:95:
                    d7:f3:ca:fa:30:3d:d5:a6:50:77:03:e3:de:eb:30:
                    17:45:48:fe:5b:76:d4:c1:03:3f:b8:99:73:ae:ad:
                    ae:e2:69:95:e2:14:1e:42:b1:ac:72:cd:0b:c6:01:
                    e3:20:8d:5a:6a:5d:19:79:17:f0:80:5f:75:fc:d5:
                    da:9c:af:07:d8:c7:96:02:a5:94:19:64:d7:9a:e4:
                    56:f1:cf:54:b9:a7:29:28:22:52:f2:c4:8a:97:04:
                    45:b1:9b:b5:4f:c0:18:53:ff:08:3f:3b:81:bd:f1:
                    d1:e9
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier: 
                87:65:C6:B6:B6:3A:0A:A6:30:BA:CB:D2:27:9E:C4:E6:2E:7F:2F:6D
            X509v3 Authority Key Identifier: 
                keyid:87:65:C6:B6:B6:3A:0A:A6:30:BA:CB:D2:27:9E:C4:E6:2E:7F:2F:6D

            X509v3 Basic Constraints: 
                CA:TRUE
    Signature Algorithm: sha256WithRSAEncryption
         71:da:8c:da:ab:9d:6d:8a:f1:9c:56:a9:7d:e2:e2:1b:fd:90:
         b7:5e:45:db:d4:69:47:ca:98:2f:b0:3b:2c:1f:49:3a:75:dd:
         1d:96:b3:bd:11:a6:d7:06:60:4f:18:11:e1:cf:db:5c:52:03:
         29:78:47:6e:36:c0:64:d8:4d:34:00:d9:94:55:48:a9:d4:b2:
         b2:ed:b8:13:fc:3d:c6:b4:61:a3:56:aa:9d:73:80:62:38:da:
         0c:94:b0:4a:e6:86:da:6a:f9:aa:f3:a4:3c:48:32:93:f7:d3:
         27:f9:2c:77:b4:91:9c:84:62:96:86:7d:d2:c8:20:79:d1:12:
         ef:f0:cc:15:31:ea:86:e9:b4:02:00:55:83:0f:6a:c6:5b:d2:
         19:67:9b:b2:44:f8:3b:36:f9:b0:02:b2:98:7d:1e:fa:95:58:
         92:92:57:68:f8:56:bb:43:db:01:08:bb:d6:ab:52:e6:c7:88:
         7a:1c:8d:f4:31:90:70:0a:dd:d2:96:7c:8b:93:8f:1f:4a:80:
         fe:3a:f8:df:82:a7:99:ac:2f:e8:02:e5:8b:fe:ec:3b:3b:0a:
         a3:c0:82:4d:f7:93:66:a1:76:6f:fa:c2:19:8e:d8:b6:b4:27:
         8c:57:22:a4:f7:e6:45:61:27:af:fc:5f:51:88:eb:32:

Setting App Authentication Method as certificate

Once you have the certificate, you will need to change the authentication method for your app in Fortanix DSM to use a certificate instead of an API key. To change the authentication method, go to the application detail page of your app, navigate to the Info tab, and open the “Change authentication method” drop-down. Select the method as “Certificate” and click Save. You will be prompted to upload a certificate. Upload your certificate and click on Update. Now your app is set to authenticate using the certificate you created.

Configuring Encryption in MongoDB

You need to start MongoDB with the options to configure encryption and point it to Fortanix DSM as the key manager. MongoDB will use the certificate you created in the earlier step to authenticate to Fortanix DSM.

NOTE:

If you already have data in MongoDB then starting MongoDB with encryption enabled will not work.
The certificate needs to be in PEM format.
It needs the private key and certificate to be concatenated together in one file.

Copy your private key followed by a certificate in a file, say client.pem. It should look as follows

To start MongoDB with encryption enabled and use a new master key, start with the following options:

/usr/bin/mongod --enableEncryption --kmipServerName   --kmipPort 5696 --kmipServerCAFile SDKMS_CA.pem --kmipClientCertificateFile client.pem

Explanation of parameters

--enableEncryption	Enable encryption at rest
--kmipServerName arg	Fortanix DSM hostname
--kmipPort arg	KMIP server port (defaults to 5696)
--kmipClientCertificateFile arg	Client certificate for authenticating to Fortanix DSM server
--kmipServerCAFile arg	CA File for validating connection to the Fortanix DSM server.

For more details on MongoDB encryption at rest and other configuration options, please see MongoDB Manual

Once MongoDB starts and connects to Fortanix DSM successfully, it will request Fortanix DSM to generate a master key (AES-256). You can check this in Fortanix DSM WebUI under the Security Objects page. Every time, MongoDB is restarted it will retrieve the value of Master Key from Fortanix DSM after authenticating with it. With Fortanix DSM you will see a complete audit trail if every time this master key is retrieved. You will also have complete control over the master key and you can revoke access to the key or disable it, in case you want to lock down your data at rest.

The following screenshot shows the activity logs for the MongoDB application and an audit trail of the master key usage.

appactivitylog Figure 5: Activity logs