The KITE protocol allows building forwarding paths for prefixes using "authenticated" Interest-Data exchanges between a mobile producer (MP) and a trusted Rendezvous Server (RV).
An MP sends a KITE request (a signed Interest), which is forwarded to the RV because the RV announces a prefix of the name. The KITE request leaves traces in the stateful forwarding plane (PIT entries), constructing a forwarding path for Data to be forwarded to the MP. The RV will verify the information carried in the KITE request (primarily the signature, and thus the term "authenticated Interest-Data exchange"), and respond with a KITE acknowledgment, a Data packet, for legitimate KITE requests. The KITE acknowledgment sent by the RV will trigger intermediate forwarders to save the reversed forwarding path for Data as Interest forwarding information, for a prefix specified by the name of the Interest-Data exchange.
A KITE request is essentially a signed Interest as specified in the v0.3 packet format (https://named-data.net/doc/NDN-packet-spec/current/signed-interest.html) that carries both a timestamp and a nonce for replay-attack prevention. A KITE request is signed and sent by an MP to be verified by an RV,
An Interest packet that satisfies the following requirements is a KITE request:
- Conforms to signed Interest specifications.
- With the trailing ApplicationParameters digest removed, the remaining leading part of the name conforms to KITE request name specifications (see below).
- The ApplicationParameters contains the expiration period for the forwarding path (optional), which is a TLV block of Type "tlv::nfd::ExpirationPeriod".
KITE request name specifications:
- Starts with an RV prefix, i.e., a prefix announced by an RV.
- Followed by a "32=KITE" keyword name component.
- Ends with a producer suffix, i.e., one or more arbitrary name components. The concatenation of an RV prefix and a producer suffix in the same KITE request name is the producer prefix specified in this name. The forwarding path to be set up is for the producer prefix.
For example, for RV prefix = /RV, producer suffix = /Alice, thus making producer prefix /RV/Alice, the full name of the corresponding KITE request should be:
A KITE acknowledgment is a Data packet sent by the RV for an Interest (a KITE request) that passes verification. A KITE request that passes the verification is supposed to be sent by the owner of the specified producer prefix for which the forwarding path is set up.
A Data packet that satisfies the following requirements is a KITE acknowledgement (note that a KITE acknowledgment is always generated in response to a KITE request):
- Has the same name with a KITE request.
- ContentType is 6 (KITE Acknowledgment).
- Carry a prefix announcement object as payload, and the "announced prefix" indicated by the PA object must be the same as the producer prefix specified in the name (refer to KITE request specifications for determining the producer prefix).
- The payload only consists of a prefix announcement object in data form, no other content.