1package signature
 2
 3import (
 4	"fmt"
 5	sign "golang.org/x/crypto/nacl/sign"
 6	rand "crypto/rand"
 7	hex "encoding/hex"
 8	"errors"
 9)
10
11const signatureSize = 128
12
13type SignKeys struct {
14    Public *[32]byte
15    Private *[64]byte
16}
17
18func (k *SignKeys) Generate() error {
19  var err error
20  k.Public = new([32]byte)
21  k.Private = new([64]byte)
22  k.Public, k.Private, err = sign.GenerateKey(rand.Reader)
23  return err
24}
25
26func (k *SignKeys) AddHexKeys(pubHex string, privHex string) error {
27  if len(pubHex) < 32 || len(privHex) < 64 {
28    return errors.New("Wrong key size, must be pub:32 priv:64 (bytes)")
29  }
30  pubKey, err := hex.DecodeString(pubHex)
31  if err != nil { return err }
32  privKey, err := hex.DecodeString(privHex)
33  if err != nil { return err }
34  k.Public = new([32]byte)
35  k.Private = new([64]byte)
36  copy(k.Public[:],pubKey[:32])
37  copy(k.Private[:],privKey[:64])
38  return nil
39}
40
41func (k *SignKeys) HexString() (string, string) {
42  pubHex := hex.EncodeToString(k.Public[:])
43  privHex := hex.EncodeToString(k.Private[:])
44  return pubHex, privHex
45}
46
47// message is a normal string (no HexString)
48func (k *SignKeys) Sign(message string) (string, error) {
49  if k.Private == nil {
50    return "", errors.New("No private key available")
51  }
52  signature := sign.Sign(nil, []byte(message), k.Private)
53  signHexFull := hex.EncodeToString(signature)
54  return signHexFull[:signatureSize], nil
55}
56
57// message is a normal string, signature and pubHex are HexStrings
58func (k *SignKeys) Verify(message, signature, pubHex string) (bool, error) {
59  msgHex := hex.EncodeToString([]byte(message))
60  signatureAndText := fmt.Sprintf("%s%s", signature, msgHex)
61  signatureToVerify, err :=  hex.DecodeString(signatureAndText)
62  if err != nil { return false, err }
63  pubKeyToVerify, err := hex.DecodeString(pubHex)
64  if err != nil { return false, err }
65  pubKey := new([32]byte)
66  copy(pubKey[:],pubKeyToVerify[:32])
67  _, result := sign.Open(nil, signatureToVerify, pubKey)
68  return result, nil
69}