Cert chains in PEM format. One cert chain should be provided per private key. Each cert chain should consist of the PEM formatted certificate for a provided private key, followed by the PEM formatted intermediate certificates (if any), in order, and not including the root CA (the root CA must be pre-known to the peer, see ca). When providing multiple cert chains, they do not have to be in the same order as their private keys in key. If the intermediate certificates are not provided, the peer will not be able to validate the certificate, and the handshake will fail.