aboutsummaryrefslogtreecommitdiff
path: root/key/sec.go
blob: 3143fb7d1961cc463f6a78abf1082ece2b68c4dd (plain)
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
package key

import (
	"bytes"
	"crypto/sha512"

	"golang.org/x/crypto/ed25519"
)

type Sec struct {
	PKAlg     [2]byte
	KDFAlg    [2]byte
	KDFRounds uint32
	Salt      [16]byte
	Checksum  [8]byte
	KeyNum    [8]byte
	Key       [ed25519.PrivateKeySize]byte
}

// Sign message
func (v *Sec) Sign(message []byte) *Sig {
	sig := &Sig{PKAlg: v.PKAlg, KeyNum: v.KeyNum}
	copy(sig.Sig[:], ed25519.Sign(ed25519.PrivateKey(v.Key[:]), message))
	return sig
}

func (v *Sec) Validate() error {
	if v.PKAlg != pkAlg {
		return ErrInvalidPK
	}
	if v.KDFAlg != kdfAlg {
		return ErrInvalidKDF
	}
	sum := sha512.Sum512(v.Key[:])
	if !bytes.Equal(sum[:len(v.Checksum)], v.Checksum[:]) {
		return ErrInvalidKey
	}
	return nil
}

func (v *Sec) MarshalBinary() ([]byte, error)    { return marshal(v) }
func (v *Sec) UnmarshalBinary(data []byte) error { return unmarshal(data, v) }

// Public key of secret key
func (v *Sec) Public() *Pub {
	key := ed25519.PrivateKey(v.Key[:]).Public().(ed25519.PublicKey)
	pub := &Pub{PKAlg: pkAlg, KeyNum: v.KeyNum}
	copy(pub.Key[:], key)
	return pub
}

func (v *Sec) Crypt(der Deriver) error {
	if der == nil || v.KDFRounds == 0 {
		return nil
	}
	xor, err := der.Derive(v.Salt[:], int(v.KDFRounds), len(v.Key))
	if err != nil {
		return err
	}
	for i := range xor {
		v.Key[i] ^= xor[i]
	}
	return nil
}

// NewSec returns a parsed and decoded secret key
func NewSec(data []byte, der Deriver) (*Sec, error) {
	sec := new(Sec)
	if err := sec.UnmarshalBinary(data); err != nil {
		return nil, err
	}
	if err := sec.Crypt(der); err != nil {
		return nil, err
	}
	return sec, sec.Validate()
}