Oracle database wallets for TDE, ZDLRA and External Authentication

 One topic that I spend a lot of time on is "wallets" and the Oracle database. When working with multiple features in the database, there are multiple wallets that are used for different purposes. Along with multiple wallets, there are 2 ways to manage wallets (mkstore and orapki), and there a multiple types of wallets, passworded, auto-login and local.

Wallet Use Cases

Below is a subset of all the places where wallets are used.  

Encryption Wallet : This wallet contains the encryption keys used by DBMS_CRYPTO, TDE and/or RMAN encrypted backups

Strong authentication: Often when external authentication is configured in the database, each database has unique certificates that are stored in a wallet.  In this blog I will refer to this as Strong Authentication. This covers all of DB authentication terms. EUS, OUD, Kerberos, RADIUS, etc.

Certificate authorities and Self-signed certificates : These are used by the database to establish external calls to websites using SSL (HTTPS).  The database can validate the certificate with an external certificate authority, or the self-signed certificate can be stored directly in the wallet.

SEPS authentication : SEPS authentication is used by Oracle clients (including the ZDLRA) to allow scripts to authenticate with a username and password that is stored in an auto-login wallet.  The connection string to the DB is used as the key to retrieve the encrypted connection information.

Real-time redo and TLS certificates for ZDLRA : When the ZDLRA is configured to utilize HTTPS for send/receiving backups, a self-signed certificate is stored in a wallet. This is the same wallet that is used for SEPS authentication of the VPC user.

You can imagine the confusion when you try to combine multiple products that use a wallet, and you want to manage those wallets separately.

Encryption Wallet 

The encryption wallet is the easiest wallet to manage because it is typically isolated from the other wallets that are in use.

The hierarchy Oracle uses to find the location of an encryption wallet is below.  It follows this hierarchy and it will use the first wallet it finds.

WALLET_ROOT : This the recommended location for the encryption wallet as of 19c. The WALLET_ROOT is a spfile/pfile setting that allows you to specify a different location for each database.  It is recommended that the wallet is stored under $ORACLE_BASE/admin/{DB name}/wallet on each node to allow for out of place upgrades.

ENCRYPTION_WALLET_LOCATION in the sqlnet.ora : This was the recommended location prior to 19c.  When multiple databases were sharing the same $ORACLE_HOME (and thus the same sqlnet.ora file), this became confusing. The workaround was to set the location using a variable representation of the DB_NAME.  

$ORACLE_BASE/admin/{DB name}/wallet : This location is the recommended location, But you should set the WALLET_ROOT, or in on an old release (less than 19c)  set the ENCRYPTION_WALLET_LOCATION.  Depending on this location to be the "default" location can cause issues when you start using a wallet for other purposes.  This same location is the default location for any Strong authentication implementations.

Since you should be on 19c, you should be using WALLET_ROOT for encryption wallet location.

NOTE: If you running databases in OCI, it is mandatory to be using WALLET_ROOT in order to utilize the recovery service.

Recommendation :

My recommendation is to always use OKV to manage TDE encryption keys, but I understand that it is a licensable product and it isn't feasible to expect that all customers are using it.

When working in a RAC environment (non-OKV) it becomes critical to have a shared TDE wallet. You may be tempted to store the wallet on ASM, or Exascale. I recommend that you DO NOT.  This makes it much more difficult to backup the wallet, and it makes it more difficult to have a shared SEPS wallet if backing up to a ZDLRA.

Store the TDE encryption wallet on ACFS, and point the WALLET_ROOT to the ACFS location mounted on each node.  When backing up the encryption wallet, copy ONLY the passworded wallet ewallet.p12 to another location to be backed up outside of the DB backups.

Strong authentication wallets

This wallet typically causes the most headaches for users.  The hierarchy Oracle uses to find the location of a Strong authentication wallet is below.  Like the encryption wallet, it follows this hierarchy and it will use the first wallet it finds.

WALLET_LOCATION in the sqlnet.ora : When multiple databases are sharing the same $ORACLE_HOME (and thus the same sqlnet.ora file), this becomes confusing. The workaround was to set the location using a variable representation of the DB_NAME as part of location string.  

$ORACLE_BASE/admin/{DB name}/wallet : This is the location that most customers place their Strong authentication wallets in since it is isolated to the Database associated with the wallet

NOTE: The issue arises when customers use a product/feature that updates the WALLET_LOCATION in the sqlnet.ora, which breaks authentication since the WALLET_LOCATION is checked first.

Use separate wallets, and leverage the TNS_ADMIN variable to point to different sqlnet.ora files and sharing the same $ORACLE_HOME.

Certificate authorities and Self-signed certificates 

The most common use case for certificate authorities is when  utilizing the DBMS_CLOUD family of products.  Products such as DBMS_CLOUD call out object storage and require a secure (HTTPS) connection. In order to open a secure connection the client needs to authenticate the certificate as  valid certificate, or use a self-signed certificate that is stored in the wallet.

This same issue is true when using DBMS_CLOUD_AI and DBMS_VECTOR_CHAIN which makes calls to external LLMs that often require a secure connection.

This wallet is controlled by setting the database property "SSL_WALLET". 

For simplicity I would recommend creating a central wallet that can be used by ALL databases on the host and is stored within $ORACLE_BASE. My favorite location is $ORACLE_BASE/cert_wallet which identifies it as containing certificate authorities.

I do not recommend adding certificates to the Strong authentication wallet, or the SEPS wallet (discussed next) as it becomes more difficult to mange multiple wallets to make updates.

SEPS authentication 

The next wallet I want to discuss is the SEPS authentication wallet. This wallet is used by Oracle clients (sqlplus, RMAN, and ZDLRA) to store the credentials for a database.

The connection string (either an ezconnect string or a tnsnames.ora entry) is added to the wallet, along with the username and password that will be used when connecting using this entry.  

The location of the wallet is stored in the sqlnet.ora file, and there are 2 parameters associated with this setting.

SQLNET.WALLET_OVERRIDE=true

WALLET_LOCATION={location on disk}

NOTE: Setting the WALLET_OVERRIDE to true disables any OPS$ usage and allows the usage of SEPS wallets for authentication. 

Setting the WALLET_LOCATION on a host that supports databases utilizing Strong authentication often causes issues if it does not specify a separate location each database using variable.  The sqlnet.ora file is only read at startup, so changes to the WALLET_LOCATION might not become apparent to after a database bounce.

Recommendation :

If you are using multiple products that use a wallet AND share the same Oracle Home, I recommend using the TNS_ADMIN variable to mange which wallet to use in scripts. 

As wallets become more common for security, separating out the use cases, if possible, will make it easier to manage and rotate authentication information.  With TNS_ADMIN you can point to a directory containing a sqlnet.ora file specific to the database, and leave the original sqlnet.ora file without a WALLET_LOCATION entry. 

Real-time redo and TLS certificates for ZDLRA 

Prior to the 19.18 DB release, configuring real-time redo for databases sending backups to the ZDLRA required a bounce of the database (to refresh the DBs copy of the sqlnet.ora), and it required the WALLET_LOCATION to be set in the sqlnet.ora.

This changed with 19.18, and I recommend you use the new location.

   The hierarchy Oracle uses to find the location of the wallet real-time wallet is below.  Like the encryption wallet, it follows this hierarchy and it will use the first wallet it finds.

WALLET_ROOT/server_seps : If the variable WALLET_ROOT is set, and a wallet exists in the server_seps subdirectory, that wallet is used by the real-time redo.  This is a HUGE improvement as it doesn't require a bounce, and it makes it much easier to avoid issues with Strong authentication, and databases that share the same $ORACLE_HOME.

NOTE: WALLET_ROOT was added in 18c. If you are still using 12.x, you need to use the sqlnet.ora.

WALLET_LOCATION in the sqlnet.ora : When multiple databases are sharing the same $ORACLE_HOME (and thus the same sqlnet.ora file), this becomes confusing. The workaround was to set the location using a variable representation of the DB_NAME.  This is what I mentioned for Strong authentication.

Recommendation :

When backing up to a ZDLRA, especially with real-time redo you should be using a SEPS wallet that is stored under WALLET_ROOT.  

Since the ZDLRA supports encrypted backups, even if you don't own ASO, I recommend creating an encryption wallet with keys to encrypt your backups.  This is much more secure, and this ability is included in the ZDLRA license.

The steps I would recommend for any customer using the ZDLRA are

• If you don't have an encryption wallet (because you don't own ASO), create one and set the  encryption keys for both the CDB and PDB (if it is multi-tenant). This does require a DB bounce to set the WALLET_ROOT, but this will allow you to have RMAN encrypted backups.
• In a RAC environment store the encryption wallet on ACFS and point WALLET_ROOT to the ACFS location.
• Store the SEPS wallet containing the VPC user credentials for the ZDLRA in the WALLET_ROOT/server_seps directory.  This will automatically be used by real-time redo starting with 19.18.
• Ensure your channel configuration for RMAN points to the WALLET_ROOT/server_seps directory on ACFS for the wallet.
• In your RMAN scripts ensure that you are pointing to a TNS_ADMIN location that has a sqlnet.ora file pointing to the WALLET_ROOT/server_seps location for WALLET_LOCATION or ensure that OEM has the correct SEPS wallet location set. 

MKSTORE vs ORAPKI

orapki 

The orapki utility manages public key infrastructure (PKI) elements, such as wallets and certificate revocation lists, from the command line.  This is the recommended method of managing wallet files.

You can use the orapki command-line utility to perform the following tasks:

• Creating and viewing signed certificates for testing purposes

• Manage Oracle wallets (except for Transparent Data Encryption keystores):

  • Create and display Oracle wallets

  • Add and remove certificate requests

  • Add and remove certificates

  • Add and remove trusted certificates

• Manage certificate revocation lists (CRLs):

  • Renaming CRLs with a hash value for certificate validation

  • Uploading, listing, viewing, and deleting CRLs in Oracle Internet Directory

NOTE: The above is directly from the 19c documentation.  You can see that orapki is used to manage certificates with no mention of managing SEPS credentials.

mkstore

The first thing you will notice with mkstore, is that the mkstore command should be considered deprecated.  Upon digging into this some more, I found a comment from Russ Lowenthal (VP of Database Security products) who mentions that the SEPS credential wallet management will not be added to orapki until AFTER 23c.

NOTE: Even though it is considered deprecated, mkstore is the only way to manage SEPS credentials from the command line, and should only be used to manage SEPS credentials.

Administer key management

I added the "Administer Key Management" command to this section because it can also be used to manage both secrets and SEPS credentials.

The following options are available and can be found in the documentation.

• add/update/delete Secret '{secret name}' for client '{client identifier}' --> secret
• add/update/delete secret '{secret name}' for client '{client identifier}' to {local optionally} auto_login keystore {keystore location}  --> SEPS

How to manage wallets

Wallet Type	How to manage contents
Encryption Keys	Utilize the "ADMINISTER KEY MANAGEMENT" statement from the database
External user authentication	Use orapki to manage certificates, or the OWM tool which uses orapki
Certificate authorities and Self-signed certificate	Use orapki to manage certificates
SEPS authentication	Use mkstore for now, as orapki does not support SEPS
Real-time redo for ZDLRA	Use mkstore for now, as orapki does not support SEPS
TLS certificates for ZDLRA	Use orapki to manage the certificates

Wallet names and type

When you look in the wallet directory you would see one, or both of these wallets.

cwallet.sso - This is an auto-login wallet.  With an auto-login wallet you can access the contents without having to provide a password. In almost all cases, you will have this type of wallet entry.

ewallet.p12 - This is the passworded wallet. In order add/change/delete entries you need to specify a password when making those changes.  

NOTE:

• If only the cwallet.sso exist, you can assume it is an auto-login only wallet.
• If both wallets exist, you can access the contents without a password, but any add/change/deletion commands will require a password and update both the passworded wallet and the auto-login wallet.
• If only the ewallet.p12 exists, to access the contents of the wallet  you must provide a password.

Standard Password Protected wallet

This is the least common wallet type (at least alone without an auto-login wallet), since it requires a password to access the contents. This is most commonly used to protect encryption keys for databases since it will require entering password to open the wallet when the database is started.   In this configuration you create a new wallet using orapki or Administore key store and provide a password.  In this case there will only be a single wallet file, ewallet.p12.

NOTE: You cannot create a non auto-login wallet with mkstore 

• orapki wallet create -wallet {wallet location}
• administer key management create keystore {wallet location}

Auto-login only wallets

You can create an auto-login wallet using e mkstore,  orapki, or the administer key manage command.  The idea of an auto-login wallet, is that you can add entries to this wallet without needing a password. You can also list the entries in the wallet using either CLI tool. In this configuration there is only a cwallet.sso file in the wallet directory

Auto-login wallets

This is the most common configuration that you will see.  There is both a passworded wallet, and an auto-login wallet. With both wallets, it requires a password to make changes, but no password is required to open the wallet and use it.  The two wallets are synchronized when you make changes.

There are two ways to create auto-login wallets.

    1. Create a non auto-login wallet using orapki or within the database, then create an auto-login wallet from the non auto-login wallet.

• orapki wallet create -wallet {wallet location}
• orapki wallet create -wallet {wallet location} -auto_login  OR
• mkstore -wrl {wallet location} -createSSO
• administer keystore create keystore {wallet location}
• administer keystore create auto_login keystore from keystore {wallet location}

     2. Create an auto-login wallet  and non auto-login wallet together

•     orapki wallet create -wallet {wallet location} -auto_login

Local Auto-login wallets

Local auto-login wallets work the same way as the auto-login wallet, EXCEPT, the wallet is encrypted in a way that makes it only usable on the host it was created.  This limits any security risks if the wallet is copied (or restored) onto a different host.

When creating a local auto-login wallet you would use 

• mkstore -wrl {wallet location} -createLSSO
• orapki wallet create -wallet {wallet location} auto_login_local
• administer keystore create local auto_login keystore from keystore {wallet location}

NOTE:

• Local auto-login wallets are much more secure as they can only be used on the host  where the wallet was created. 
• When backing up wallets, this includes Encryption wallets, only backup the ewallet.p12 file.  This ensures that a password is required to utilize the wallet.

NOTE: When only backing up the ewallet.p12, be sure you know the password so that you can recreate the auto-login wallet.

• ALWAYS review the permissions on your wallet files, especially the auto-login wallet files containing credentials.  Any user that can access the auto-login wallet file can utilize the credentials contained within the wallet.

ASM/Exascale for Encryption wallets

You probably noticed that I am not a fan of ASM/Exascale as an encryption wallet location, even though ASM in mentioned in the documentation. 

I will add more to this section, but this is my reasoning for not preferring ASM.

1. It's easy to forget backing up the wallet file.  Having it on ASM requires copying it back to the file system to get backed up.  It is very easy to forget about this, rotate the keys, and not have a wallet backup.
2. WALLET_ROOT is becoming the starting point for different wallet files, not just encryption wallets.  ZDLRA is the first example. When WALLET_ROOT points to ASM or Exascale, then the same wallet cannot be used by many tools because they only expect wallets on the file system.

Shared wallets make sense, that's why I prefer ACFS, or a mounted filesystem for WALLET_ROOT.

Summary 

Starting with DB 19.18, you have the ability to store individual credential wallets for real-time redo transportation when leveraging ZDLRA for backups.  You can also use the TNS_ADMIN variable to set a different location when using SEPS authentication.  It is now possible to manage multiple wallets separately without having conflicts between products and features.

MY RECOMMENDATIONS (summary):

• Use Oracle Key Vault (OKV) for encryption keys.  OKV is an Oracle product specifically designed to securely store and manage encryption keys, and much more.  OKV has tight integration with the Oracle Database.  If you are not using OKV, at least store Encryption Keys on ACFS as the shared location (not ASM or Exascale).

• Use WALLET_ROOT if you are on 18c+.  This will continue to be used products to help separate wallet locations for different uses cases.  The ZDLRA is the first of many products to use the hierarchy for wallet files. 

• Backup only the ewallet.p12.  This is the passworded wallet and with the password it can be used to recreate the auto-login wallet. This is especially critical for Encryption keys.

BUT - Make sure you know the password. Without the password, you can't recreate the auto-login wallet.

• Lock down permissions on wallet files to only the account that needs access, especially the cwallet.sso file (auto-login).

• Whenever possible create local auto-login wallets that can only be used on the source host where the wallet was created. This wallet, however,  cannot be shared across nodes.

• Keep your SEPS wallets separate by utilizing the TNS_ADMIN variable and having a custom sqlnet.ora file.

• If you are backing up to a ZDLRA create an encryption wallet with keys, and set the WALLET_ROOT location.  Put the SEPS wallet for ZDLRA under WALLET_ROOT/server_seps.  This wallet can also be used for the TPCS certificate if you configure HTTPS.   Keep this configuration separate to avoid conflicts with other products.