// RFC 6962 calls this a “Merkle consistency proof.”
type TreeProof []Hash

// ProveTree returns the proof that the tree of size t contains
// as a prefix all the records from the tree of smaller size n.
func ProveTree(t, n int64, h HashReader) (TreeProof, error) {
	if t < 1 || n < 1 || n > t {
		return nil, fmt.Errorf("tlog: invalid inputs in ProveTree")
	}
	indexes := treeProofIndex(0, t, n, nil)
	if len(indexes) == 0 {

	// tlog.TreeHash(older.N, thr) above, so assuming thr is caching tiles,
	// there are no new access to the server here, and these operations cannot fail.
	fmt.Fprintf(&buf, "proof of misbehavior:\n\t%v", h)
	if p, err := tlog.ProveTree(newer.N, older.N, thr); err != nil {
		fmt.Fprintf(&buf, "\tinternal error: %v\n", err)
	} else if err := tlog.CheckTree(p, newer.N, newer.Hash, older.N, h); err != nil {