forked from keybase/client
/
shared_dh.go
333 lines (291 loc) · 10.6 KB
/
shared_dh.go
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package libkb
import (
"fmt"
"sync"
keybase1 "github.com/keybase/client/go/protocol/keybase1"
context "golang.org/x/net/context"
)
func NewSharedDHSecretKeyBox(innerKey NaclDHKeyPair, receiverKey NaclDHKeyPair, senderKey NaclDHKeyPair, generation keybase1.SharedDHKeyGeneration) (keybase1.SharedDHSecretKeyBox, error) {
_, secret, err := innerKey.ExportPublicAndPrivate()
if err != nil {
return keybase1.SharedDHSecretKeyBox{}, err
}
encInfo, err := receiverKey.Encrypt(secret, &senderKey)
if err != nil {
return keybase1.SharedDHSecretKeyBox{}, err
}
boxStr, err := PacketArmoredEncode(encInfo)
if err != nil {
return keybase1.SharedDHSecretKeyBox{}, err
}
return keybase1.SharedDHSecretKeyBox{
Box: boxStr,
ReceiverKID: receiverKey.GetKID(),
Generation: generation,
}, nil
}
type sharedDHSecretKeyBoxesResp struct {
Boxes []keybase1.SharedDHSecretKeyBox `json:"boxes"`
Status AppStatus `json:"status"`
}
func (s *sharedDHSecretKeyBoxesResp) GetAppStatus() *AppStatus {
return &s.Status
}
// SharedDHKeyMap is a map of Generation numbers to
// DH private keys, for decrypting data.
type SharedDHKeyMap map[keybase1.SharedDHKeyGeneration]NaclDHKeyPair
// SharedDHKeyring holds on to all versions of the Shared DH key.
// Generation=0 should be nil, but all others should be present.
type SharedDHKeyring struct {
Contextified
sync.Mutex
uid keybase1.UID
generations SharedDHKeyMap
}
// NewSharedDHKeyring makes a new SharedDH keyring for a given UID.
func NewSharedDHKeyring(g *GlobalContext, uid keybase1.UID) (*SharedDHKeyring, error) {
if uid.IsNil() {
return nil, fmt.Errorf("NewSharedDHKeyring called with nil uid")
}
return &SharedDHKeyring{
Contextified: NewContextified(g),
uid: uid,
generations: make(SharedDHKeyMap),
}, nil
}
func (s *SharedDHKeyring) GetUID() keybase1.UID {
return s.uid
}
// PrepareBoxesForNewDevice encrypts the shared keys for a new device.
// The result boxes will be pushed to the server.
func (s *SharedDHKeyring) PrepareBoxesForNewDevice(ctx context.Context, receiverKey NaclDHKeyPair, senderKey NaclDHKeyPair) (boxes []keybase1.SharedDHSecretKeyBox, err error) {
s.Lock()
defer s.Unlock()
for generation, fullSharedDHKey := range s.generations {
box, err := NewSharedDHSecretKeyBox(fullSharedDHKey, receiverKey, senderKey, generation)
if err != nil {
return nil, err
}
boxes = append(boxes, box)
}
s.G().Log.CDebugf(ctx, "SharedDHKeyring#PrepareBoxesForNewDevice(%s -> %s) -> %s boxes",
senderKey.GetKID(), receiverKey.GetKID(), len(boxes))
return boxes, nil
}
func (s *SharedDHKeyring) HasAnyKeys() bool {
return s.CurrentGeneration() > 0
}
// CurrentGeneration returns what generation we're on. The version possible
// Version is 1. Version 0 implies no keys are available.
func (s *SharedDHKeyring) CurrentGeneration() keybase1.SharedDHKeyGeneration {
s.Lock()
defer s.Unlock()
return s.currentGenerationLocked()
}
func (s *SharedDHKeyring) currentGenerationLocked() keybase1.SharedDHKeyGeneration {
return keybase1.SharedDHKeyGeneration(len(s.generations))
}
func (s *SharedDHKeyring) SharedDHKey(ctx context.Context, g keybase1.SharedDHKeyGeneration) *NaclDHKeyPair {
s.Lock()
defer s.Unlock()
key, found := s.generations[g]
s.G().Log.CDebugf(ctx, "SharedDHKeyring#SharedDHKey %s -> %s", g, found)
if !found {
return nil
}
return &key
}
// Clone makes a deep copy of this DH keyring.
func (s *SharedDHKeyring) Clone() (*SharedDHKeyring, error) {
s.Lock()
defer s.Unlock()
ret, err := NewSharedDHKeyring(s.G(), s.uid)
if err != nil {
return nil, err
}
ret.mergeLocked(s.generations)
return ret, nil
}
// Update will take the existing SharedDHKeyring, and return an updated
// copy, that will be synced with the server's version of our SharedDHKeyring.
func (s *SharedDHKeyring) Update(ctx context.Context) (ret *SharedDHKeyring, err error) {
ret, err = s.Clone()
if err != nil {
return nil, err
}
err = ret.Sync(ctx)
return ret, err
}
// Sync our SharedDHKeyring with the server. It will either add all new
// Secret boxes since our last update, or not at all if there was an error.
// Pass it a standard Go network context.
func (s *SharedDHKeyring) Sync(ctx context.Context) (err error) {
return s.syncAsConfiguredDevice(ctx, nil, nil)
}
// `lctx` and `upak` are optional
func (s *SharedDHKeyring) SyncWithExtras(ctx context.Context, lctx LoginContext, upak *keybase1.UserPlusAllKeys) (err error) {
return s.syncAsConfiguredDevice(ctx, lctx, upak)
}
// `lctx` and `upak` are optional
func (s *SharedDHKeyring) syncAsConfiguredDevice(ctx context.Context, lctx LoginContext, upak *keybase1.UserPlusAllKeys) (err error) {
uid, deviceID, _, activeDecryptionKey := s.G().ActiveDevice.AllFields()
if !s.uid.Equal(uid) {
return fmt.Errorf("UID changed on SharedDHKeyring")
}
if deviceID.IsNil() {
return fmt.Errorf("missing configured deviceID")
}
return s.sync(ctx, lctx, upak, deviceID, activeDecryptionKey)
}
// `lctx` and `upak` are optional
func (s *SharedDHKeyring) SyncAsPaperKey(ctx context.Context, lctx LoginContext, upak *keybase1.UserPlusAllKeys, deviceID keybase1.DeviceID, decryptionKey GenericKey) (err error) {
if deviceID.IsNil() {
return fmt.Errorf("missing deviceID")
}
// Note this `== nil` check might not work, as it might be a typed nil.
if decryptionKey == nil {
return fmt.Errorf("missing decryption key")
}
return s.sync(ctx, lctx, upak, deviceID, decryptionKey)
}
// `lctx` and `upak` are optional
func (s *SharedDHKeyring) sync(ctx context.Context, lctx LoginContext, upak *keybase1.UserPlusAllKeys, deviceID keybase1.DeviceID, decryptionKey GenericKey) (err error) {
defer s.G().CTrace(ctx, "SharedDHKeyring#sync", func() error { return err })()
s.G().Log.CDebugf(ctx, "SharedDHKeyring#sync(%v, %v)", lctx != nil, upak != nil)
s.Lock()
defer s.Unlock()
boxes, err := s.fetchBoxesLocked(ctx, lctx, deviceID)
if err != nil {
return err
}
if upak == nil {
upak, err = s.getUPAK(ctx, lctx, upak)
if err != nil {
return err
}
}
newKeys, err := s.importLocked(ctx, boxes, decryptionKey, newSharedDHChecker(upak))
if err != nil {
return err
}
s.mergeLocked(newKeys)
return nil
}
func (s *SharedDHKeyring) getUPAK(ctx context.Context, lctx LoginContext, upak *keybase1.UserPlusAllKeys) (*keybase1.UserPlusAllKeys, error) {
if upak != nil {
return upak, nil
}
upakArg := NewLoadUserByUIDArg(ctx, s.G(), s.uid)
upakArg.LoginContext = lctx
upak, _, err := s.G().GetUPAKLoader().Load(upakArg)
return upak, err
}
func (s *SharedDHKeyring) mergeLocked(m SharedDHKeyMap) (err error) {
for k, v := range m {
s.generations[k] = v.Clone()
}
return nil
}
func (s *SharedDHKeyring) fetchBoxesLocked(ctx context.Context, lctx LoginContext, deviceID keybase1.DeviceID) (ret []keybase1.SharedDHSecretKeyBox, err error) {
defer s.G().CTrace(ctx, "SharedDHKeyring#fetchBoxesLocked", func() error { return err })()
var sessionR SessionReader
if lctx != nil {
sessionR = lctx.LocalSession()
}
var resp sharedDHSecretKeyBoxesResp
err = s.G().API.GetDecode(APIArg{
Endpoint: "key/fetch_shared_dh_secrets",
Args: HTTPArgs{
"generation": I{int(s.currentGenerationLocked())},
"device_id": S{deviceID.String()},
},
SessionType: APISessionTypeREQUIRED,
SessionR: sessionR,
RetryCount: 5, // It's pretty bad to fail this, so retry.
NetContext: ctx,
}, &resp)
if err != nil {
return nil, err
}
ret = resp.Boxes
s.G().Log.CDebugf(ctx, "| Got back %d boxes from server", len(ret))
return ret, nil
}
// sharedDHChecker checks the secret boxes returned from the server
// against the public keys advertised in the user's sigchain. As we import
// keys, we check them against these two maps. In particular, we check that
// the box was encryted with a valid device Box key (though it can be now revoked).
// And we check that the public key corresponds to what was signed in as a
// shared_dh_key.
type sharedDHChecker struct {
allowedEncryptingKIDs map[keybase1.KID]bool
expectedSharedDHKIDs map[keybase1.SharedDHKeyGeneration]keybase1.KID
}
func newSharedDHChecker(upak *keybase1.UserPlusAllKeys) *sharedDHChecker {
ret := sharedDHChecker{
allowedEncryptingKIDs: make(map[keybase1.KID]bool),
expectedSharedDHKIDs: make(map[keybase1.SharedDHKeyGeneration]keybase1.KID),
}
isEncryptionKey := func(k keybase1.PublicKey) bool {
return !k.IsSibkey && k.PGPFingerprint == ""
}
for _, r := range upak.Base.RevokedDeviceKeys {
if isEncryptionKey(r.Key) {
ret.allowedEncryptingKIDs[r.Key.KID] = true
}
}
for _, k := range upak.Base.DeviceKeys {
if isEncryptionKey(k) {
ret.allowedEncryptingKIDs[k.KID] = true
}
}
for _, k := range upak.Base.SharedDHKeys {
ret.expectedSharedDHKIDs[keybase1.SharedDHKeyGeneration(k.Gen)] = k.Kid
}
return &ret
}
func importSharedDHKey(box *keybase1.SharedDHSecretKeyBox, activeDecryptionKey GenericKey, wantedGeneration keybase1.SharedDHKeyGeneration, checker *sharedDHChecker) (ret *NaclDHKeyPair, err error) {
if box.Generation != wantedGeneration {
return nil, SharedDHImportError{fmt.Sprintf("bad generation returned: %d", box.Generation)}
}
if !activeDecryptionKey.GetKID().Equal(box.ReceiverKID) {
return nil, SharedDHImportError{fmt.Sprintf("wrong encryption kid: %s", box.ReceiverKID.String())}
}
rawKey, encryptingKID, err := activeDecryptionKey.DecryptFromString(box.Box)
if err != nil {
return nil, err
}
if len(checker.allowedEncryptingKIDs) == 0 {
return nil, SharedDHImportError{fmt.Sprintf("no allowed encrypting kids")}
}
if !checker.allowedEncryptingKIDs[encryptingKID] {
return nil, SharedDHImportError{fmt.Sprintf("unexpected encrypting kid: %s", encryptingKID)}
}
key, err := MakeNaclDHKeyPairFromSecretBytes(rawKey)
if err != nil {
return nil, err
}
expectedKID, found := checker.expectedSharedDHKIDs[box.Generation]
if !found {
// This error can mean the SDH keyring is behind and should be synced.
return nil, SharedDHImportError{fmt.Sprintf("No known SDH generation: %d", box.Generation)}
}
if !expectedKID.Equal(key.GetKID()) {
return nil, SharedDHImportError{fmt.Sprintf("Wrong public key for gen=%d; %s != %s", box.Generation, expectedKID, key.GetKID())}
}
return &key, nil
}
func (s *SharedDHKeyring) importLocked(ctx context.Context, boxes []keybase1.SharedDHSecretKeyBox, decryptionKey GenericKey, checker *sharedDHChecker) (ret SharedDHKeyMap, err error) {
defer s.G().CTrace(ctx, "SharedDHKeyring#importLocked", func() error { return err })()
ret = make(SharedDHKeyMap)
nxt := s.currentGenerationLocked() + 1
for _, box := range boxes {
naclDHKey, err := importSharedDHKey(&box, decryptionKey, nxt, checker)
if err != nil {
return nil, err
}
ret[nxt] = *naclDHKey
nxt++
}
return ret, nil
}