forked from keybase/client
/
naclwrap.go
776 lines (651 loc) · 19.6 KB
/
naclwrap.go
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
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
// Copyright 2015 Keybase, Inc. All rights reserved. Use of
// this source code is governed by the included BSD license.
package libkb
import (
"bytes"
"crypto/hmac"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"fmt"
"io"
"github.com/agl/ed25519"
keybase1 "github.com/keybase/client/go/protocol/keybase1"
"golang.org/x/crypto/nacl/box"
)
type NaclSignature [ed25519.SignatureSize]byte
type NaclSigInfo struct {
Kid keybase1.BinaryKID `codec:"key"`
Payload []byte `codec:"payload,omitempty"`
Sig NaclSignature `codec:"sig"`
SigType int `codec:"sig_type"`
HashType int `codec:"hash_type"`
Detached bool `codec:"detached"`
Version int `codec:"version,omitempty"`
Prefix SignaturePrefix `codec:"prefix,omitempty"`
}
type NaclEncryptionInfo struct {
Ciphertext []byte `codec:"ciphertext"`
EncryptionType int `codec:"enc_type"`
Nonce []byte `codec:"nonce"`
Receiver []byte `codec:"receiver_key"`
Sender []byte `codec:"sender_key"`
}
const NaclDHKeysize = 32
// TODO: Ideally, ed25519 would expose how many random bytes it needs.
const NaclSigningKeySecretSize = 32
// TODO: Ideally, box would expose how many random bytes it needs.
const NaclDHKeySecretSize = 32
// Todo: Ideally, box would specify nonce size
const NaclDHNonceSize = 24
type NaclSigningKeyPublic [ed25519.PublicKeySize]byte
type NaclSigningKeyPrivate [ed25519.PrivateKeySize]byte
func (k NaclSigningKeyPrivate) Sign(msg []byte) *NaclSignature {
return (*NaclSignature)(ed25519.Sign((*[ed25519.PrivateKeySize]byte)(&k), msg))
}
func (k NaclSigningKeyPublic) Verify(msg []byte, sig *NaclSignature) bool {
return ed25519.Verify((*[ed25519.PublicKeySize]byte)(&k), msg, (*[ed25519.SignatureSize]byte)(sig))
}
type NaclSigningKeyPair struct {
Public NaclSigningKeyPublic
Private *NaclSigningKeyPrivate
}
var _ GenericKey = NaclSigningKeyPair{}
type NaclDHKeyPublic [NaclDHKeysize]byte
type NaclDHKeyPrivate [NaclDHKeysize]byte
type NaclDHKeyPair struct {
Public NaclDHKeyPublic
Private *NaclDHKeyPrivate
}
var _ GenericKey = NaclDHKeyPair{}
func importNaclHex(s string, typ byte, bodyLen int) (ret []byte, err error) {
kid := keybase1.KIDFromString(s)
return importNaclKid(kid.ToBytes(), typ, bodyLen)
}
func importNaclKid(bkid []byte, typ byte, bodyLen int) (ret []byte, err error) {
l := len(bkid)
if l != bodyLen+3 {
err = BadKeyError{fmt.Sprintf("Wrong length; wanted %d, got %d", bodyLen+3, l)}
return
}
if bkid[0] != byte(KeybaseKIDV1) || bkid[l-1] != byte(IDSuffixKID) || bkid[1] != typ {
err = BadKeyError{"bad header or trailer bytes"}
return
}
ret = bkid[2:(l - 1)]
return
}
func ImportNaclSigningKeyPairFromBytes(pub []byte, priv []byte) (ret NaclSigningKeyPair, err error) {
var body []byte
if body, err = importNaclKid(pub, byte(KIDNaclEddsa), ed25519.PublicKeySize); err != nil {
return
}
copy(ret.Public[:], body)
if priv == nil {
} else if len(priv) != ed25519.PrivateKeySize {
err = BadKeyError{"Secret key was wrong size"}
} else {
ret.Private = &NaclSigningKeyPrivate{}
copy(ret.Private[:], priv)
}
return
}
func ImportKeypairFromKID(k keybase1.KID) (key GenericKey, err error) {
kid := k.ToBytes()
l := len(kid)
if l < 3 {
err = BadKeyError{"KID was way too short"}
return
}
if kid[0] != byte(KeybaseKIDV1) || kid[l-1] != byte(IDSuffixKID) {
err = BadKeyError{"bad header or trailer found"}
return
}
raw := kid[2:(l - 1)]
switch kid[1] {
case byte(KIDNaclEddsa):
if len(raw) != ed25519.PublicKeySize {
err = BadKeyError{"Bad EdDSA key size"}
} else {
tmp := NaclSigningKeyPair{}
copy(tmp.Public[:], raw)
key = tmp
}
case byte(KIDNaclDH):
if len(raw) != NaclDHKeysize {
err = BadKeyError{"Bad DH key size"}
} else {
tmp := NaclDHKeyPair{}
copy(tmp.Public[:], raw)
key = tmp
}
default:
err = BadKeyError{fmt.Sprintf("Bad key prefix: %d", kid[1])}
}
return
}
func ImportNaclSigningKeyPairFromHex(s string) (ret NaclSigningKeyPair, err error) {
var body []byte
if body, err = importNaclHex(s, byte(KIDNaclEddsa), ed25519.PublicKeySize); err != nil {
return
}
copy(ret.Public[:], body)
return
}
func ImportNaclDHKeyPairFromBytes(pub []byte, priv []byte) (ret NaclDHKeyPair, err error) {
var body []byte
if body, err = importNaclKid(pub, byte(KIDNaclDH), NaclDHKeysize); err != nil {
return
}
copy(ret.Public[:], body)
if priv == nil {
} else if len(priv) != NaclDHKeysize {
err = BadKeyError{"Secret key was wrong size"}
} else {
ret.Private = &NaclDHKeyPrivate{}
copy(ret.Private[:], priv)
}
return
}
func ImportNaclDHKeyPairFromHex(s string) (ret NaclDHKeyPair, err error) {
var body []byte
if body, err = importNaclHex(s, byte(KIDNaclDH), NaclDHKeysize); err != nil {
return
}
copy(ret.Public[:], body)
return
}
func (k NaclDHKeyPublic) GetKID() keybase1.KID {
return k.GetBinaryKID().ToKID()
}
func (k NaclDHKeyPublic) GetBinaryKID() keybase1.BinaryKID {
prefix := []byte{
byte(KeybaseKIDV1),
byte(KIDNaclDH),
}
suffix := byte(IDSuffixKID)
out := append(prefix, k[:]...)
out = append(out, suffix)
return keybase1.BinaryKID(out)
}
func (k NaclDHKeyPair) GetFingerprintP() *PGPFingerprint {
return nil
}
func (k NaclDHKeyPair) GetAlgoType() AlgoType {
return KIDNaclDH
}
func (k NaclSigningKeyPair) GetAlgoType() AlgoType {
return KIDNaclEddsa
}
func (k NaclSigningKeyPublic) GetBinaryKID() keybase1.BinaryKID {
prefix := []byte{
byte(KeybaseKIDV1),
byte(KIDNaclEddsa),
}
suffix := byte(IDSuffixKID)
out := append(prefix, k[:]...)
out = append(out, suffix)
return keybase1.BinaryKID(out)
}
func (k NaclSigningKeyPublic) GetKID() keybase1.KID {
return k.GetBinaryKID().ToKID()
}
func (k NaclSigningKeyPair) GetKID() (ret keybase1.KID) {
return k.Public.GetKID()
}
func (k NaclSigningKeyPair) GetBinaryKID() (ret keybase1.BinaryKID) {
return k.Public.GetBinaryKID()
}
func (k NaclSigningKeyPair) ToShortIDString() string {
return k.Public.GetKID().ToShortIDString()
}
func (k NaclDHKeyPair) ToShortIDString() string {
return k.Public.GetKID().ToShortIDString()
}
func (k NaclSigningKeyPair) VerboseDescription() string {
return fmt.Sprintf("255-bit EdDSA signing key (%s)", k.ToShortIDString())
}
func (k NaclDHKeyPair) VerboseDescription() string {
return fmt.Sprintf("255-bit Curve25519 DH key (%s)", k.ToShortIDString())
}
func (k NaclSigningKeyPair) GetFingerprintP() *PGPFingerprint {
return nil
}
func (k NaclDHKeyPair) GetKID() keybase1.KID {
return k.Public.GetKID()
}
func (k NaclDHKeyPair) GetBinaryKID() (ret keybase1.BinaryKID) {
return k.Public.GetBinaryKID()
}
func (k NaclSigningKeyPair) CheckSecretKey() error {
if k.Private == nil {
return NoSecretKeyError{}
}
return nil
}
func (k NaclSigningKeyPair) HasSecretKey() bool {
return k.Private != nil
}
func (k NaclSigningKeyPair) Encode() (string, error) {
return k.GetKID().String(), nil
}
func (k NaclDHKeyPair) Encode() (string, error) {
return k.GetKID().String(), nil
}
func (k NaclDHKeyPair) CheckSecretKey() error {
if k.Private == nil {
return NoSecretKeyError{}
}
return nil
}
func (k NaclDHKeyPair) HasSecretKey() bool {
return k.Private != nil
}
func (k NaclSigningKeyPair) CanSign() bool { return k.Private != nil }
func (k NaclDHKeyPair) CanSign() bool { return false }
func (k NaclSigningKeyPair) Sign(msg []byte) (ret *NaclSigInfo, err error) {
if k.Private == nil {
err = NoSecretKeyError{}
return
}
// Version 0 is just over the unprefixed message (assume version 0 if no version present)
// Version 1 is the same.
ret = &NaclSigInfo{
Kid: k.GetBinaryKID(),
Payload: msg,
Sig: *k.Private.Sign(msg),
SigType: SigKbEddsa,
HashType: HashPGPSha512,
Detached: true,
Version: 0,
}
return
}
func (k NaclSigningKeyPair) SecretSymmetricKey(reason EncryptionReason) ([]byte, error) {
return nil, KeyCannotEncryptError{}
}
type SignaturePrefix string
type EncryptionReason string
func (p SignaturePrefix) hasNullByte() bool {
return bytes.IndexByte([]byte(p), byte(0)) != -1
}
func (p SignaturePrefix) Prefix(msg []byte) []byte {
prefix := append([]byte(p), 0)
return append(prefix, msg...)
}
func (r EncryptionReason) Bytes() []byte {
return []byte(r)
}
func (k NaclSigningKeyPair) SignV2(msg []byte, prefix SignaturePrefix) (ret *NaclSigInfo, err error) {
if k.Private == nil {
err = NoSecretKeyError{}
return
}
if prefix.hasNullByte() || len(prefix) == 0 {
err = BadSignaturePrefixError{}
return
}
// Version 0 is just over the unprefixed message (assume version 0 if no version present)
// Version 1 is the same.
ret = &NaclSigInfo{
Kid: k.GetBinaryKID(),
Payload: msg,
Sig: *k.Private.Sign(prefix.Prefix(msg)),
SigType: SigKbEddsa,
HashType: HashPGPSha512,
Detached: true,
Version: 2,
Prefix: prefix,
}
return
}
func (k NaclSigningKeyPair) SignToString(msg []byte) (sig string, id keybase1.SigID, err error) {
naclSig, err := k.Sign(msg)
if err != nil {
return
}
packet, err := naclSig.ToPacket()
if err != nil {
return
}
body, err := packet.Encode()
if err != nil {
return
}
sig = base64.StdEncoding.EncodeToString(body)
id = ComputeSigIDFromSigBody(body)
return
}
func (k NaclSigningKeyPair) VerifyStringAndExtract(ctx VerifyContext, sig string) (msg []byte, id keybase1.SigID, err error) {
var keyInSignature GenericKey
var fullSigBody []byte
keyInSignature, msg, fullSigBody, err = NaclVerifyAndExtract(sig)
if err != nil {
return
}
kidInSig := keyInSignature.GetKID()
kidWanted := k.GetKID()
if kidWanted.NotEqual(kidInSig) {
err = WrongKidError{kidInSig, kidWanted}
return
}
id = ComputeSigIDFromSigBody(fullSigBody)
return
}
// NaclVerifyAndExtract interprets the given string as a NaCl-signed messaged, in
// the keybase NaclSigInfo (v1) format. It will check that the signature verified, and if so,
// will return the key that was used for the verification, the payload of the signature,
// the full body of the decoded SignInfo, and an error
func NaclVerifyAndExtract(s string) (key GenericKey, payload []byte, fullBody []byte, err error) {
fullBody, err = base64.StdEncoding.DecodeString(s)
if err != nil {
return nil, nil, nil, err
}
packet, err := DecodePacket(fullBody)
if err != nil {
return nil, nil, nil, err
}
naclSig, ok := packet.Body.(*NaclSigInfo)
if !ok {
err = UnmarshalError{"NACL signature"}
return nil, nil, nil, err
}
var nk *NaclSigningKeyPublic
nk, err = naclSig.Verify()
if err != nil {
return nil, nil, nil, err
}
key = NaclSigningKeyPair{Public: *nk}
payload = naclSig.Payload
return key, payload, fullBody, nil
}
func (k NaclSigningKeyPair) VerifyString(ctx VerifyContext, sig string, msg []byte) (id keybase1.SigID, err error) {
extractedMsg, resID, err := k.VerifyStringAndExtract(ctx, sig)
if err != nil {
return
}
if !FastByteArrayEq(extractedMsg, msg) {
err = BadSigError{"wrong payload"}
return
}
id = resID
return
}
func (k NaclDHKeyPair) SignToString(msg []byte) (sig string, id keybase1.SigID, err error) {
err = KeyCannotSignError{}
return
}
func (k NaclDHKeyPair) VerifyStringAndExtract(ctx VerifyContext, sig string) (msg []byte, id keybase1.SigID, err error) {
err = KeyCannotVerifyError{}
return
}
func (k NaclDHKeyPair) VerifyString(ctx VerifyContext, sig string, msg []byte) (id keybase1.SigID, err error) {
err = KeyCannotVerifyError{}
return
}
func (s *NaclSigInfo) ToPacket() (ret *KeybasePacket, err error) {
return NewKeybasePacket(s, TagSignature, KeybasePacketV1)
}
func (p KeybasePacket) ToNaclSigInfo() (*NaclSigInfo, error) {
ret, ok := p.Body.(*NaclSigInfo)
if !ok {
return nil, UnmarshalError{"Signature"}
}
return ret, nil
}
func KIDToNaclSigningKeyPublic(bk []byte) *NaclSigningKeyPublic {
if len(bk) != 3+ed25519.PublicKeySize {
return nil
}
if bk[0] != byte(KeybaseKIDV1) || bk[1] != byte(KIDNaclEddsa) || bk[len(bk)-1] != byte(IDSuffixKID) {
return nil
}
var ret NaclSigningKeyPublic
copy(ret[:], bk[2:len(bk)-1])
return &ret
}
func (s NaclSigInfo) Verify() (*NaclSigningKeyPublic, error) {
key := KIDToNaclSigningKeyPublic(s.Kid)
if key == nil {
return nil, BadKeyError{}
}
switch s.Version {
case 0, 1:
if !key.Verify(s.Payload, &s.Sig) {
return nil, VerificationError{}
}
case 2:
if !key.Verify(s.Prefix.Prefix(s.Payload), &s.Sig) {
return nil, VerificationError{}
}
default:
return nil, UnhandledSignatureError{}
}
return key, nil
}
func (s *NaclSigInfo) ArmoredEncode() (ret string, err error) {
return PacketArmoredEncode(s)
}
func (k NaclSigningKeyPair) ExportPublicAndPrivate() (RawPublicKey, RawPrivateKey, error) {
return RawPublicKey(k.GetKID().ToBytes()), RawPrivateKey(k.Private[:]), nil
}
func (k NaclDHKeyPair) ExportPublicAndPrivate() (RawPublicKey, RawPrivateKey, error) {
return RawPublicKey(k.GetKID().ToBytes()), RawPrivateKey(k.Private[:]), nil
}
func makeNaclSigningKeyPair(reader io.Reader) (NaclSigningKeyPair, error) {
pub, priv, err := ed25519.GenerateKey(reader)
if err != nil {
return NaclSigningKeyPair{}, err
}
return NaclSigningKeyPair{
Public: *pub,
Private: (*NaclSigningKeyPrivate)(priv),
}, nil
}
// MakeNaclSigningKeyPairFromSecret makes a signing key pair given a
// secret. Of course, the security of depends entirely on the
// randomness of the bytes in the secret.
func MakeNaclSigningKeyPairFromSecret(secret [NaclSigningKeySecretSize]byte) (NaclSigningKeyPair, error) {
r := bytes.NewReader(secret[:])
kp, err := makeNaclSigningKeyPair(r)
if err != nil {
return NaclSigningKeyPair{}, err
}
if r.Len() > 0 {
return NaclSigningKeyPair{}, fmt.Errorf("Did not use %d secret byte(s)", r.Len())
}
return kp, err
}
func GenerateNaclSigningKeyPair() (NaclSigningKeyPair, error) {
return makeNaclSigningKeyPair(rand.Reader)
}
func makeNaclDHKeyPair(reader io.Reader) (NaclDHKeyPair, error) {
pub, priv, err := box.GenerateKey(reader)
if err != nil {
return NaclDHKeyPair{}, err
}
return NaclDHKeyPair{
Public: *pub,
Private: (*NaclDHKeyPrivate)(priv),
}, nil
}
// MakeNaclDHKeyPairFromSecret makes a DH key pair given a secret. Of
// course, the security of depends entirely on the randomness of the
// bytes in the secret.
func MakeNaclDHKeyPairFromSecret(secret [NaclDHKeySecretSize]byte) (NaclDHKeyPair, error) {
r := bytes.NewReader(secret[:])
kp, err := makeNaclDHKeyPair(r)
if err != nil {
return NaclDHKeyPair{}, err
}
if r.Len() > 0 {
return NaclDHKeyPair{}, fmt.Errorf("Did not use %d secret byte(s)", r.Len())
}
return kp, err
}
func GenerateNaclDHKeyPair() (NaclDHKeyPair, error) {
return makeNaclDHKeyPair(rand.Reader)
}
func KbOpenSig(armored string) ([]byte, error) {
return base64.StdEncoding.DecodeString(armored)
}
func SigAssertKbPayload(armored string, expected []byte) (sigID keybase1.SigID, err error) {
var byt []byte
var packet *KeybasePacket
var sig *NaclSigInfo
var ok bool
if byt, err = KbOpenSig(armored); err != nil {
return
}
if packet, err = DecodePacket(byt); err != nil {
return
}
if sig, ok = packet.Body.(*NaclSigInfo); !ok {
err = UnmarshalError{"NaCl Signature"}
return
}
if !FastByteArrayEq(expected, sig.Payload) {
err = BadSigError{"wrong payload"}
}
sigID = ComputeSigIDFromSigBody(byt)
return
}
// EncryptToString fails for this type of key.
func (k NaclSigningKeyPair) EncryptToString(plaintext []byte, sender GenericKey) (ciphertext string, err error) {
err = KeyCannotEncryptError{}
return
}
// DecryptFromString fails for this type of key.
func (k NaclSigningKeyPair) DecryptFromString(ciphertext string) (msg []byte, sender keybase1.KID, err error) {
err = KeyCannotDecryptError{}
return
}
// CanEncrypt always returns false for a signing key pair.
func (k NaclSigningKeyPair) CanEncrypt() bool { return false }
// CanDecrypt always returns false for a signing key pair.
func (k NaclSigningKeyPair) CanDecrypt() bool { return false }
// CanEncrypt always returns true for an encryption key pair.
func (k NaclDHKeyPair) CanEncrypt() bool { return true }
// CanDecrypt returns true if there's a private key available
func (k NaclDHKeyPair) CanDecrypt() bool { return k.Private != nil }
func (k NaclDHKeyPair) IsNil() bool {
var empty NaclDHKeyPublic
return bytes.Equal(k.Public[:], empty[:])
}
// Encrypt a message for the given sender. If sender is nil, an ephemeral
// keypair will be invented
func (k NaclDHKeyPair) Encrypt(msg []byte, sender *NaclDHKeyPair) (*NaclEncryptionInfo, error) {
if sender == nil {
if tmp, err := GenerateNaclDHKeyPair(); err == nil {
sender = &tmp
} else {
return nil, err
}
} else if sender.Private == nil {
return nil, NoSecretKeyError{}
}
var nonce [NaclDHNonceSize]byte
if nRead, err := rand.Read(nonce[:]); err != nil {
return nil, err
} else if nRead != NaclDHNonceSize {
return nil, fmt.Errorf("Short random read: %d", nRead)
}
var ctext []byte
ctext = box.Seal(ctext, msg, &nonce, ((*[32]byte)(&k.Public)), ((*[32]byte)(sender.Private)))
ret := &NaclEncryptionInfo{
Ciphertext: ctext,
EncryptionType: KIDNaclDH,
Nonce: nonce[:],
Receiver: k.GetKID().ToBytes(),
Sender: sender.GetKID().ToBytes(),
}
return ret, nil
}
// EncryptToString encrypts the plaintext using DiffieHelman; the this object is
// the receiver, and the passed sender is optional. If not provided, we'll make
// up an ephemeral key.
func (k NaclDHKeyPair) EncryptToString(plaintext []byte, sender GenericKey) (string, error) {
var senderDh *NaclDHKeyPair
if sender != nil {
var ok bool
if senderDh, ok = sender.(*NaclDHKeyPair); !ok {
return "", NoSecretKeyError{}
}
}
info, err := k.Encrypt(plaintext, senderDh)
if err != nil {
return "", nil
}
return PacketArmoredEncode(info)
}
func (k NaclDHKeyPair) SecretSymmetricKey(reason EncryptionReason) ([]byte, error) {
if !k.CanDecrypt() {
return nil, NoSecretKeyError{}
}
if len(reason) < 8 {
return nil, KeyGenError{Msg: "reason must be at least 8 bytes"}
}
mac := hmac.New(sha256.New, k.Private[:])
mac.Write(reason.Bytes())
symmetricKey := mac.Sum(nil)
return symmetricKey, nil
}
// ToPacket implements the Packetable interface.
func (k *NaclEncryptionInfo) ToPacket() (ret *KeybasePacket, err error) {
return NewKeybasePacket(k, TagEncryption, KeybasePacketV1)
}
// DecryptFromString decrypts the output of EncryptToString above,
// and returns the KID of the other end.
func (k NaclDHKeyPair) DecryptFromString(ciphertext string) (msg []byte, sender keybase1.KID, err error) {
var kbp *KeybasePacket
var nei *NaclEncryptionInfo
var ok bool
if kbp, err = DecodeArmoredPacket(ciphertext); err != nil {
return
}
if nei, ok = kbp.Body.(*NaclEncryptionInfo); !ok {
err = UnmarshalError{"NaCl Encryption"}
return
}
return k.Decrypt(nei)
}
// Decrypt a NaclEncryptionInfo packet, and on success return the plaintext
// and the KID of the sender (which might be an ephemeral key).
func (k NaclDHKeyPair) Decrypt(nei *NaclEncryptionInfo) (plaintext []byte, sender keybase1.KID, err error) {
if k.Private == nil {
err = NoSecretKeyError{}
return
}
if nei.EncryptionType != KIDNaclDH {
err = DecryptBadPacketTypeError{}
return
}
var nonce [NaclDHNonceSize]byte
if len(nei.Nonce) != NaclDHNonceSize {
err = DecryptBadNonceError{}
return
}
copy(nonce[:], nei.Nonce)
var gk GenericKey
if gk, err = ImportKeypairFromKID(keybase1.KIDFromSlice(nei.Sender)); err != nil {
return
}
var senderDH NaclDHKeyPair
var ok bool
if senderDH, ok = gk.(NaclDHKeyPair); !ok {
err = DecryptBadSenderError{}
return
}
rkid := keybase1.KIDFromSlice(nei.Receiver)
if k.GetKID().NotEqual(rkid) {
err = DecryptWrongReceiverError{}
return
}
if plaintext, ok = box.Open(plaintext, nei.Ciphertext, &nonce,
((*[32]byte)(&senderDH.Public)), ((*[32]byte)(k.Private))); !ok {
err = DecryptOpenError{}
return
}
sender = senderDH.GetKID()
return
}