Bundle Protocol Data Representation
E. Birrane, Sarah Heiner, Ken McKeever · 2022
Instantiated Block BIB-HMAC-SHA2 BCB-AES-GCM Figure C.1 Block definitions and relationships.BPSec-related blocks are defined hierarchically.CDDL representation, the structures are divided into two classes: instantiated blocks and logical blocks.Instantiated blocks are those which are actually populated with field values and can be present as part of a bundle.In contrast, logical blocks introduce fields, but are not intended to be populated; instead, these blocks provide structure for other blocks to further define.For example, in Figure C.1, the BIB-HMAC-SHA2 block defined in RFC 9173 is built upon the BIB, which is in turn built upon the ASB.The BIB and ASB are defined in BPSec and are derived from the Canonical Block which is based on a BPv7 Block. C.2 Data RepresentationThis appendix provides a description of block formats from BPv7, BPSec, and the default security context which may be helpful to the reader implementing BP functionality.There are two specifications useful here.Concise Binary Object Representation (CBOR) is a binary serialization data format which is designed with efficiency of implementation in mind.The Concise Data Definition Language is a machine-readable data structure representation format which is used to represent CBOR data objects to facilitate design communication.In this appendix, BPv7 blocks are described using CDDL notation. C.2.1 CBOR BasicsCBOR is defined in RFC 8949 1 and provides a binary serialization format that attempts to allow for implementation with a relatively small code base and message size [4].There are several predefined CBOR types which have a specified common encoding scheme.The structures defined by BPv7, BPSec, and the Default Security Contexts all make use of these types to construct and define blocks. C.2.1.1 CBOR ObjectivesFrom RFC 8949, the objectives of CBOR are:1.The representation must be able to unambiguously encode most common data formats used in Internet standards.