Comparing public key values

The signatures on user and server certificates exchanged during authentication are always checked. You can enable an additional level of verification for public keys, by having the value of the key passed in the certificates checked against the value of the key listed in the HCL Domino® Directory. It is possible for users to authenticate with a server, but have a mismatch between the value of the public keys in their certificates and what is listed for them in the Domino Directory.

About this task

This extra level of key verification protects against misuse of a lost or compromised ID file. Typically, if an ID file is lost, its owner needs to be registered to create a new ID file and directory entry; and if the ID file has been compromised then the owner's public and private keys need to be rolled-over and that new set of keys need to be certified (thus updating the directory entry). By enabling directory-level key checking, an attacker in possession of the old ID file will not be able to use it to access the server, even though that old ID file may contain a valid certificate.

You can also choose to control whether a log message is generated if authentication succeeds but a mismatch is detected. This allows administrators to detect when the ID file contents have gotten out of sync with directory entries, but to do so without preventing those users from authenticating because of public key mismatches.

Procedure

  1. From the Domino Administrator, click the Configuration tab, and open the Server document.
  2. Click the Security tab.
  3. In the Security Settings section, click the list next to Compare public keys and choose one of the following options:
    • Enforce key checking for all Notes users and Domino servers --to compare the key value in the certificates passed during authentication against the key value stored in the Domino Directory. Any user or server not listed in a trusted directory will be treated as if it failed this verification check and will not be allowed to access this server.
    • Enforce key checking for Notes users and Domino servers listed in trusted directories only -- to compare the key value in the certificates passed during authentication against the key value stored in the directory only when the user or server is listed in a trusted directory. Any user or server not listed in a trusted directory will be treated as if it passed this verification check.
      Note: This option allows administrators to give users not listed in the directory access to databases and applications on the server. For example, a database may have its Access Control List configured to give editor access enabled for users listed in the Domino Directory, and reader access for everyone else. So if this key checking option is enabled, users not listed in the directory can still access the server to use the database, for which they will have reader access only.
    • Do not enforce key checking -- if you want only the certificate signatures checked during authentication, but not verify the keys against the directory contents.
  4. Click the list next to Log public key mismatches and choose one of the following options:
    • Log key mismatches for all Notes users and Domino servers -- to log events that occur when the key value in the certificates passed during authentication does not match the key value stored in the Domino Directory.
    • Log key mismatches for Notes users and Domino servers listed in trusted directories only -- to log events that occur when the key value in the certificate passed during authentication does not match the key value stored in the directory only when the user or server is listed in a trusted directory.
    • Do not log key mismatches -- to log only authentication failures.
  5. Stop and restart the server so that the changes take effect. The server polls every hour to see if these settings have changed, so if the server is not restarted it may be as long as an hour before the new settings take effect.