Method importTree

mls/src/main/java/org/bouncycastle/mls/protocol/Group.java:2368–2403

(byte[] treeHash, TreeKEMPublicKey external, List<Extension> extensions)

        return new GroupContext(suite, groupID, epoch, tree.getRootHash(), transcriptHash.getConfirmed(), extensions);
    }

    private TreeKEMPublicKey importTree(byte[] treeHash, TreeKEMPublicKey external, List<Extension> extensions)
        throws Exception
    {
        // Check if extensions contain a ratchet tree
        TreeKEMPublicKey outTree = null;
        for (Extension ext : extensions)
        {
            outTree = ext.getRatchetTree();
            if (outTree != null)
            {
                break;
            }
        }
        if (external != null)
        {
            outTree = external;
        }
        else if (outTree == null)
        {
            throw new Exception("No tree available");
        }

        outTree.setSuite(suite);
        outTree.setHashAll();
        if (!Arrays.areEqual(outTree.getRootHash(), treeHash))
        {
            throw new Exception("Tree does not match GroupInfo");
        }

        if (!outTree.verifyParentHash())
        {
            throw new Exception("Invalid tree");
        }

        return outTree;
    }

    private List<KeyScheduleEpoch.PSKWithSecret> resolve(List<PreSharedKeyID> psks)