// Init initializes a local repository.
//
// The latest root.json is fetched from remote storage, verified using rootKeys
// and threshold, and then saved in local storage. It is expected that rootKeys
// were securely distributed with the software being updated.
func (c *Client) Init(rootKeys []*data.Key, threshold int) error {
if len(rootKeys) < threshold {
return ErrInsufficientKeys
}
rootJSON, err := c.downloadMetaUnsafe("root.json")
if err != nil {
return err
}
c.db = verify.NewDB()
rootKeyIDs := make([]string, len(rootKeys))
for i, key := range rootKeys {
id := key.ID()
rootKeyIDs[i] = id
if err := c.db.AddKey(id, key); err != nil {
return err
}
}
role := &data.Role{Threshold: threshold, KeyIDs: rootKeyIDs}
if err := c.db.AddRole("root", role); err != nil {
return err
}
if err := c.decodeRoot(rootJSON); err != nil {
return err
}
return c.local.SetMeta("root.json", rootJSON)
}
// getLocalMeta decodes and verifies metadata from local storage.
//
// The verification of local files is purely for consistency, if an attacker
// has compromised the local storage, there is no guarantee it can be trusted.
func (c *Client) getLocalMeta() error {
meta, err := c.local.GetMeta()
if err != nil {
return err
}
if rootJSON, ok := meta["root.json"]; ok {
// unmarshal root.json without verifying as we need the root
// keys first
s := &data.Signed{}
if err := json.Unmarshal(rootJSON, s); err != nil {
return err
}
root := &data.Root{}
if err := json.Unmarshal(s.Signed, root); err != nil {
return err
}
c.db = verify.NewDB()
for id, k := range root.Keys {
if err := c.db.AddKey(id, k); err != nil {
return err
}
}
for name, role := range root.Roles {
if err := c.db.AddRole(name, role); err != nil {
return err
}
}
if err := c.db.Verify(s, "root", 0); err != nil {
return err
}
c.consistentSnapshot = root.ConsistentSnapshot
} else {
return ErrNoRootKeys
}
if snapshotJSON, ok := meta["snapshot.json"]; ok {
snapshot := &data.Snapshot{}
if err := verify.UnmarshalTrusted(snapshotJSON, snapshot, "snapshot", c.db); err != nil {
return err
}
c.snapshotVer = snapshot.Version
}
if targetsJSON, ok := meta["targets.json"]; ok {
targets := &data.Targets{}
if err := verify.UnmarshalTrusted(targetsJSON, targets, "targets", c.db); err != nil {
return err
}
c.targetsVer = targets.Version
c.targets = targets.Targets
}
if timestampJSON, ok := meta["timestamp.json"]; ok {
timestamp := &data.Timestamp{}
if err := verify.UnmarshalTrusted(timestampJSON, timestamp, "timestamp", c.db); err != nil {
return err
}
c.timestampVer = timestamp.Version
}
c.localMeta = meta
return nil
}