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
|
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
*/
package main
import (
"crypto/hmac"
"crypto/rand"
"crypto/subtle"
"golang.org/x/crypto/blake2s"
"golang.org/x/crypto/curve25519"
"hash"
)
/* KDF related functions.
* HMAC-based Key Derivation Function (HKDF)
* https://tools.ietf.org/html/rfc5869
*/
func HMAC1(sum *[blake2s.Size]byte, key, in0 []byte) {
mac := hmac.New(func() hash.Hash {
h, _ := blake2s.New256(nil)
return h
}, key)
mac.Write(in0)
mac.Sum(sum[:0])
}
func HMAC2(sum *[blake2s.Size]byte, key, in0, in1 []byte) {
mac := hmac.New(func() hash.Hash {
h, _ := blake2s.New256(nil)
return h
}, key)
mac.Write(in0)
mac.Write(in1)
mac.Sum(sum[:0])
}
func KDF1(t0 *[blake2s.Size]byte, key, input []byte) {
HMAC1(t0, key, input)
HMAC1(t0, t0[:], []byte{0x1})
return
}
func KDF2(t0, t1 *[blake2s.Size]byte, key, input []byte) {
var prk [blake2s.Size]byte
HMAC1(&prk, key, input)
HMAC1(t0, prk[:], []byte{0x1})
HMAC2(t1, prk[:], t0[:], []byte{0x2})
setZero(prk[:])
return
}
func KDF3(t0, t1, t2 *[blake2s.Size]byte, key, input []byte) {
var prk [blake2s.Size]byte
HMAC1(&prk, key, input)
HMAC1(t0, prk[:], []byte{0x1})
HMAC2(t1, prk[:], t0[:], []byte{0x2})
HMAC2(t2, prk[:], t1[:], []byte{0x3})
setZero(prk[:])
return
}
func isZero(val []byte) bool {
acc := 1
for _, b := range val {
acc &= subtle.ConstantTimeByteEq(b, 0)
}
return acc == 1
}
/* This function is not used as pervasively as it should because this is mostly impossible in Go at the moment */
func setZero(arr []byte) {
for i := range arr {
arr[i] = 0
}
}
func newPrivateKey() (sk NoisePrivateKey, err error) {
// clamping: https://cr.yp.to/ecdh.html
_, err = rand.Read(sk[:])
sk[0] &= 248
sk[31] &= 127
sk[31] |= 64
return
}
func (sk *NoisePrivateKey) publicKey() (pk NoisePublicKey) {
apk := (*[NoisePublicKeySize]byte)(&pk)
ask := (*[NoisePrivateKeySize]byte)(sk)
curve25519.ScalarBaseMult(apk, ask)
return
}
func (sk *NoisePrivateKey) sharedSecret(pk NoisePublicKey) (ss [NoisePublicKeySize]byte) {
apk := (*[NoisePublicKeySize]byte)(&pk)
ask := (*[NoisePrivateKeySize]byte)(sk)
curve25519.ScalarMult(&ss, ask, apk)
return ss
}
|
