SoftHSM is an implementation of a cryptographic store accessible through a PKCS #11 interface. You can use it to explore PKCS #11 without having a Hardware Security Module. It is being developed as a part of the OpenDNSSEC project. SoftHSM uses Botan for its cryptographic operations.
OpenDNSSEC handles and stores its cryptographic keys via the PKCS #11 interface. This interface specifies how to communicate with cryptographic devices such as HSM:s (Hardware Security Modules) and smart cards. The purpose of these devices is, among others, to generate cryptographic keys and sign information without revealing private-key material to the outside world. They are often designed to perform well on these specific tasks compared to ordinary processes in a normal computer.
A potential problem with the use of the PKCS #11 interface is that it might limit the wide spread use of OpenDNSSEC, since a potential user might not be willing to invest in a new hardware device. To counter this effect, OpenDNSSEC is providing a software implementation of a generic cryptographic device with a PKCS#11 interface, the SoftHSM. SoftHSM is designed to meet the requirements of OpenDNSSEC, but can also work together with other cryptographic products because of the PKCS #11 interface.
How to install and use softHSM is described here.