The membership service provider (MSP) is responsible for creating digital identities for peers and users of the organization. The identities of peers must be configured in an existing network in order for a new entity to participate in the channel.

Fabric CA is an implementation of the MSP and provides a mechanism for registering users from a network member and issuing them digital identities (X.509 certificates). Fabric CA typically runs inside a Docker container. Each Fabric CA is configured with a backend database (the default being SQLite, with other options, such as PostgreSQL or MySQL) which stores the registered identities, as well as their X.509 certificates. Fabric CA does not store the private keys of the users.