Class MTCContentSigner

java.lang.Object
org.bouncycastle.cert.plants.MTCContentSigner
All Implemented Interfaces:
ContentSigner
public class MTCContentSigner extends Object implements ContentSigner
Issuer-side ContentSigner that emits an MTC signatureValue (an encoded MTCProof) for an EE Merkle Tree certificate per Section 6.2 of draft-ietf-plants-merkle-tree-certs.

The signer is plugged into the standard X509v3CertificateBuilder.build(ContentSigner) flow. As the TBSCertificate DER bytes stream out of the builder into getOutputStream(), this class captures them; when getSignature() is invoked it:

  1. Takes the entry's index from the serial number the builder wrote (serial = (log_number << 48) | index, Section 6.2), checking the log number is that of the supplied MTCLog.
  2. Derives the MerkleTreeCertEntry leaf hash via MerkleTreeCertificateValidator.computeEntryHash(byte[], MerkleTreeHash) and evaluates the supplied inclusion proof for that index within the log's subtree [start, end) (Section 4.3.2) to obtain the subtree hash.
  3. Delegates to MTCCosigner.cosignSubtree(MTCLog, byte[]) to produce the cosigner's MTCSignature.
  4. Wraps the inclusion proof and the cosigner signature in an MTCProof and returns its TLS wire encoding.

This is the single-cosigner binding used by the worked examples: a standalone certificate (Section 6.3 of the draft) carrying one cosigner signature and no log-entry extensions. Issuers with multiple cosigners or extensions should compose the MTCCosigner, MTCProof and MerkleTreeHash primitives directly; landmark-relative certificates (Section 6.4, no signatures) are built via LandmarkCertificateManager.buildLandmarkCertificate(long, long, TBSCertificateLogEntry, SubjectPublicKeyInfo, MerkleTreePrimitives.SubtreeInfo, List, MerkleTreeHash).

  • Constructor Details

    • MTCContentSigner

      public MTCContentSigner(MTCLog log, byte[] inclusionProof, MTCCosigner cosigner)
      The cosigner's identity is taken from MTCCosigner.getCosignerId() — the CA-as-cosigner case is just a MTCCosigner constructed with log.getCa().getCaId() as its cosigner ID (Section 5.3 of the draft). Witnesses, regulators, federated peers or any other entity with a distinct trust anchor ID work via the same constructor by constructing the cosigner with their own ID.
      Parameters:
      log - issuance log + subtree window [log.getStart(), log.getEnd()) — also supplies the CA (via MTCLog.getCa()) and therefore the hash function and log ID
      inclusionProof - the subtree inclusion proof (Section 4.3) for the EE's entry, as the concatenated sibling hashes from the leaf up to the subtree root — the same bytes that land in the resulting MTCProof (a single sibling hash for a two-entry subtree)
      cosigner - cosigner driver bound to its trust anchor ID, signature algorithm and key

  • Method Details

    • getAlgorithmIdentifier

      public org.bouncycastle.asn1.x509.AlgorithmIdentifier getAlgorithmIdentifier()
      Description copied from interface: ContentSigner
      Return the algorithm identifier describing the signature algorithm and parameters this signer generates.
      Specified by:
      getAlgorithmIdentifier in interface ContentSigner
      Returns:
      algorithm oid and parameters.

    • getOutputStream

      public OutputStream getOutputStream()
      Description copied from interface: ContentSigner
      Returns a stream that will accept data for the purpose of calculating a signature. Use org.bouncycastle.util.io.TeeOutputStream if you want to accumulate the data on the fly as well.
      Specified by:
      getOutputStream in interface ContentSigner
      Returns:
      an OutputStream

    • getSignature

      public byte[] getSignature()
      Description copied from interface: ContentSigner
      Returns a signature based on the current data written to the stream, since the start or the last call to getSignature().
      Specified by:
      getSignature in interface ContentSigner
      Returns:
      bytes representing the signature.