PKCS#11

PKCS#11 is an interface that enables an LDAP user to use crypto hardware. By using PKCS#11, an LDAP user can use the crypto hardware to securely store the key database file and accelerate cryptographic operations.

You can use PKCS#11 interface to configure the following types of crypto devices.
Accelerators
These devices are connected to the host by a permanent connection such as a card slot or a LAN connection. The primary purpose of an accelerator is to increase the number of cryptographic operations per second for a server. Private key storage is maintained in an SSL KDB (Key Database) file, which is loaded into the accelerator as needed. This type of device must be considered for use when the objective is to increase the number of cryptographic operations only. Stronger hardware protection of the server's private key is not a concern.
Key storage with accelerators
These devices are primarily for server applications where cryptographic performance is an issue and stringent security of the server's private key is also essential. The private key and certificate are stored on the device. If a cryptographic operation requires use of the private key, the hardware device uses the key locally on the adapter. The application can never access the key in an unencrypted format. These devices usually employ tamper-resistant procedures to protect external access to the key.