Changes

Since version 0.1

• Signature
  • New SignatureSha256WithEcdsa signature type for Elliptic Curve Digital Signature Algorithm (ECDSA).
  • KeyLocatorDigest renamed to KeyDigest. The specification now explicitly allows KeyDigest to be a SHA256 of any type of the key.
  • KeyLocator field is now defined to be optionally present in generic SignatureInfo block. SignatureSha256WithRsa and SignatureSha256WithEcdsa still require KeyLocator to be always present.

Since CCNx 0.7.2

• General

  • XML-based ccnb packet encoding is replaced by TLV encoding

• Name

  • The name encoding is changed from binary XML to TLV format
  • The discussions on naming conventions and the use of special markers inside NameComponents are removed from packet specification, and will be covered by a separate technical document
  • Deprecated zero-length name component

• Interest Packet

  • Nonce is changed from optional to required

  • PublisherPublicKeyDigest is replaced by PublisherPublicKeyLocator

  • AnswerOriginKind is simplified from 4bits to a 1-bit MustBeFresh

  • FaceID has been removed

  • InterestLifetime changes the unit to the number of milliseconds

  • Removed Bloom Filter from Exclude

  • Changed default semantics of staleness

    Specifically, NDN-TLV Interest without any selectors will bring any data that matches the name, and only when MustBeFresh selector is enabled it will try to honor freshness, specified in Data packets. With Binary XML encoded Interests, the default behavior was to bring “fresh” data and return “stale” data only when AnswerOriginKind was set to 3.

    Application developers must be aware of this change, reexamine the Interest expression code, and enable MustBeFresh selector when necessary.

• Data Packet

  • The structure of Data packet is changed:
    • Name, MetaInfo, Content, Signature{SignatureInfo, SignatureValue}
  • SignedInfo is renamed to MetaInfo and its content is changed
  • PublisherPublicKeyDigest and ExtOpt are removed.
  • Timestamp is removed
  • KeyLocator is moved to be inside the Signature (SignatureInfo) block
  • Three content types, ENCR, GONE, and NACK are removed
  • FreshnessSeconds is renamed to FreshnessPeriod and is expressed in units of milliseconds

• Signature

  • Signature is moved to the end of Data packet.

  • KeyLocator is moved to be a part of the SignatureInfo block, if it is applicable for the specific signature type.

    The rationale for the move is to make Signature (sequence of SignatureInfo and SignatureValue TLVs) self-contained and self-sufficient.

  • Signature type (or signing method information) is expressed as an assigned integer value (with no assumed default), rather than OID.

  • Added support for hash-only “signature”

  • The current specification does not define Merkle Hash Tree Aggregated Signatures, but it is expected that such (or similar) signatures will be defined in future version of this specification