Securely store an identity in the keychain.
You store an identity in or retrieve an identity from a keychain much as you would a certificate, as described in Storing a Certificate in the Keychain.
Private keys have a one-to-many relationship with certificates. That is, a single private key can be paired with multiple certificates, but a given certificate corresponds to exactly one private key. As a result, the fields that distinguish one identity from another are the same as those of the certificate it contains. As a result, working with identities as keychain items is very much like working with certificates, with a few minor adjustments: