MTCCosigner (Bouncy Castle Library 1.85 API Specification)

All Known Implementing Classes:

BcMTCCosigner, JcaMTCCosigner
```
public interface MTCCosigner
```
Operator interface for producing a cosigner signature over the subtree [start, end) of an MTC issuance log, per Section 5.3 of draft-ietf-plants-merkle-tree-certs. Implementations encode the MTCCosignedMessage, drive a signer bound to the cosigner's private key at construction, and return the result already packaged as an MTCSignature carrying the cosigner's trust anchor ID.
JCA-free and lightweight-crypto-free. Concrete bindings: org.bouncycastle.cert.plants.bc.BcMTCCosigner (lightweight) and org.bouncycastle.cert.plants.jcajce.JcaMTCCosigner (JCA).

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`MTCSignature`	`cosignSubtree(MTCLog log, byte[] subtreeHash)`	Cosigns the subtree `[log.getStart(), log.getEnd())` of the issuance log identified by `log.getLogId()`.
`byte[]`	`getCosignerId()`

- Method Detail
  - getCosignerId
```
byte[] getCosignerId()
```
    Returns:
    
    the binary trust anchor ID of this cosigner — the value that appears in MTCSignature.getCosignerId() on every signature produced by this instance. Per Section 5.3 of the draft, when the CA itself is acting as a cosigner this is the CA's own trust anchor ID.
  - cosignSubtree
```
MTCSignature cosignSubtree(MTCLog log,
                           byte[] subtreeHash)
                    throws java.io.IOException
```
    Cosigns the subtree [log.getStart(), log.getEnd()) of the issuance log identified by log.getLogId().
    
    Throws:
    
    java.io.IOException - if the CosignedMessage cannot be encoded or the underlying signing operation fails