1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
package stfe
import (
"context"
"crypto"
"fmt"
"reflect"
"sync"
"time"
"github.com/golang/glog"
"github.com/google/certificate-transparency-go/schedule"
"github.com/system-transparency/stfe/trillian"
"github.com/system-transparency/stfe/types"
)
// StateManager coordinates access to the log's tree heads and (co)signatures
type StateManager interface {
Latest(context.Context) (*types.SignedTreeHead, error)
ToSign(context.Context) (*types.SignedTreeHead, error)
Cosigned(context.Context) (*types.SignedTreeHead, error)
AddCosignature(context.Context, *[types.VerificationKeySize]byte, *[types.SignatureSize]byte) error
Run(context.Context)
}
// StateManagerSingle implements the StateManager interface. It is assumed that
// the log server is running on a single-instance machine. So, no coordination.
type StateManagerSingle struct {
client trillian.Client
signer crypto.Signer
interval time.Duration
deadline time.Duration
sync.RWMutex
// cosigned is the current cosigned tree head that is being served
cosigned types.SignedTreeHead
// tosign is the current tree head that is being cosigned by witnesses
tosign types.SignedTreeHead
// cosignature keeps track of all cosignatures for the tosign tree head
cosignature map[[types.HashSize]byte]*types.SigIdent
}
func NewStateManagerSingle(client trillian.Client, signer crypto.Signer, interval, deadline time.Duration) (*StateManagerSingle, error) {
sm := &StateManagerSingle{
client: client,
signer: signer,
interval: interval,
deadline: deadline,
}
ctx, _ := context.WithTimeout(context.Background(), sm.deadline)
sth, err := sm.Latest(ctx)
if err != nil {
return nil, fmt.Errorf("Latest: %v", err)
}
sm.cosigned = *sth
sm.tosign = *sth
sm.cosignature = map[[types.HashSize]byte]*types.SigIdent{
*sth.SigIdent[0].KeyHash: sth.SigIdent[0], // log signature
}
return sm, nil
}
func (sm *StateManagerSingle) Run(ctx context.Context) {
schedule.Every(ctx, sm.interval, func(ctx context.Context) {
ictx, _ := context.WithTimeout(ctx, sm.deadline)
nextTreeHead, err := sm.Latest(ictx)
if err != nil {
glog.Warningf("rotate failed: Latest: %v", err)
return
}
sm.Lock()
defer sm.Unlock()
sm.rotate(nextTreeHead)
})
}
func (sm *StateManagerSingle) Latest(ctx context.Context) (*types.SignedTreeHead, error) {
th, err := sm.client.GetTreeHead(ctx)
if err != nil {
return nil, fmt.Errorf("LatestTreeHead: %v", err)
}
sth, err := th.Sign(sm.signer)
if err != nil {
return nil, fmt.Errorf("sign: %v", err)
}
return sth, nil
}
func (sm *StateManagerSingle) ToSign(_ context.Context) (*types.SignedTreeHead, error) {
sm.RLock()
defer sm.RUnlock()
return &sm.tosign, nil
}
func (sm *StateManagerSingle) Cosigned(_ context.Context) (*types.SignedTreeHead, error) {
sm.RLock()
defer sm.RUnlock()
return &sm.cosigned, nil
}
func (sm *StateManagerSingle) AddCosignature(_ context.Context, vk *[types.VerificationKeySize]byte, sig *[types.SignatureSize]byte) error {
sm.Lock()
defer sm.Unlock()
if err := sm.tosign.TreeHead.Verify(vk, sig); err != nil {
return fmt.Errorf("Verify: %v", err)
}
witness := types.Hash(vk[:])
if _, ok := sm.cosignature[*witness]; ok {
return fmt.Errorf("signature-signer pair is a duplicate")
}
sm.cosignature[*witness] = &types.SigIdent{
Signature: sig,
KeyHash: witness,
}
glog.V(3).Infof("accepted new cosignature from witness: %x", *witness)
return nil
}
// rotate rotates the log's cosigned and stable STH. The caller must aquire the
// source's read-write lock if there are concurrent reads and/or writes.
func (sm *StateManagerSingle) rotate(next *types.SignedTreeHead) {
if reflect.DeepEqual(sm.cosigned.TreeHead, sm.tosign.TreeHead) {
// cosigned and tosign are the same. So, we need to merge all
// cosignatures that we already had with the new collected ones.
for _, sigident := range sm.cosigned.SigIdent {
if _, ok := sm.cosignature[*sigident.KeyHash]; !ok {
sm.cosignature[*sigident.KeyHash] = sigident
}
}
glog.V(3).Infof("cosigned tree head repeated, merged signatures")
}
var cosignatures []*types.SigIdent
for _, sigident := range sm.cosignature {
cosignatures = append(cosignatures, sigident)
}
// Update cosigned tree head
sm.cosigned.TreeHead = sm.tosign.TreeHead
sm.cosigned.SigIdent = cosignatures
// Update to-sign tree head
sm.tosign = *next
sm.cosignature = map[[types.HashSize]byte]*types.SigIdent{
*next.SigIdent[0].KeyHash: next.SigIdent[0], // log signature
}
glog.V(3).Infof("rotated tree heads")
}
|
