The key management and naming service API all return a `KeyInfo` object. The `id` is a universally unique identifier for the key. The `name` is local to the key chain.
The **key id** is the SHA-256 [multihash](https://github.com/multiformats/multihash) of its public key. The *public key* is a [protobuf encoding](https://github.com/libp2p/js-libp2p-crypto/blob/master/src/keys/keys.proto.js) containing a type and the [DER encoding](https://en.wikipedia.org/wiki/X.690) of the PKCS [SubjectPublicKeyInfo](https://www.ietf.org/rfc/rfc3279.txt).
A private key is stored as an encrypted PKCS 8 structure in the PEM format. It is protected by a key generated from the key chain's *passPhrase* using **PBKDF2**.
The default options for generating the derived encryption key are in the `dek` object. This, along with the passPhrase, is the input to a `PBKDF2` function.
The actual physical storage of an encrypted key is left to implementations of [interface-datastore](https://github.com/ipfs/interface-datastore/). A key benifit is that now the key chain can be used in browser with the [js-datastore-level](https://github.com/ipfs/js-datastore-level) implementation.
CMS, aka [PKCS #7](https://en.wikipedia.org/wiki/PKCS) and [RFC 5652](https://tools.ietf.org/html/rfc5652), describes an encapsulation syntax for data protection. It is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. Basically, `cms.encrypt` creates a DER message that can be only be read by someone holding the private key.