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pgp.go
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/
pgp.go
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package pgp
import (
"bytes"
"crypto"
"io"
"os"
"github.com/deweppro/go-errors"
"golang.org/x/crypto/openpgp"
"golang.org/x/crypto/openpgp/armor"
"golang.org/x/crypto/openpgp/clearsign"
"golang.org/x/crypto/openpgp/packet"
)
type (
Config struct {
Name, Email, Comment string
}
Cert struct {
Public []byte
Private []byte
}
)
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
type (
store struct {
key *openpgp.Entity
conf *packet.Config
headers map[string]string
}
Signer interface {
SetKey(b []byte, passwd string) error
SetKeyFromFile(filename string, passwd string) error
SetHash(hash crypto.Hash, bits int)
PublicKey() ([]byte, error)
PublicKeyBase64() ([]byte, error)
Sign(in io.Reader, out io.Writer) error
}
)
func New() Signer {
return &store{
conf: &packet.Config{
DefaultHash: crypto.SHA512,
RSABits: 4096,
},
headers: make(map[string]string),
}
}
func (v *store) SetKey(b []byte, passwd string) error {
r := bytes.NewReader(b)
return v.readKey(r, passwd)
}
func (v *store) SetHash(hash crypto.Hash, bits int) {
v.conf.DefaultHash = hash
v.conf.RSABits = bits
}
func (v *store) SetHeaders(headers ...string) error {
h, err := createHeaders(headers)
if err != nil {
return err
}
v.headers = mergeHeaders(v.headers, h)
return nil
}
func (v *store) SetKeyFromFile(filename string, passwd string) error {
r, err := os.Open(filename)
if err != nil {
return errors.WrapMessage(err, "read key from file")
}
return v.readKey(r, passwd)
}
func (v *store) PublicKey() ([]byte, error) {
if v.key == nil {
return nil, errors.New("key is empty")
}
var buf bytes.Buffer
if err := v.key.Serialize(&buf); err != nil {
return nil, errors.WrapMessage(err, "serialize public key")
}
return buf.Bytes(), nil
}
func (v *store) PublicKeyBase64() ([]byte, error) {
if v.key == nil {
return nil, errors.New("key is empty")
}
var buf bytes.Buffer
enc, err := armor.Encode(&buf, openpgp.PublicKeyType, v.headers)
if err != nil {
return nil, errors.WrapMessage(err, "init armor encoder")
}
if err = v.key.Serialize(enc); err != nil {
return nil, errors.WrapMessage(err, "serialize public key")
}
if err = enc.Close(); err != nil {
return nil, errors.WrapMessage(err, "close armor encoder")
}
return buf.Bytes(), nil
}
func (v *store) readKey(r io.ReadSeeker, passwd string) error {
block, err := armor.Decode(r)
if err != nil {
return errors.WrapMessage(err, "armor decode key")
}
if block.Type != openpgp.PrivateKeyType {
return errors.WrapMessage(err, "invalid key type")
}
if _, err = r.Seek(0, 0); err != nil {
return errors.WrapMessage(err, "seek key file")
}
keys, err := openpgp.ReadArmoredKeyRing(r)
if err != nil {
return errors.WrapMessage(err, "read armored key")
}
v.key = keys[0]
if v.key.PrivateKey.Encrypted {
if err = v.key.PrivateKey.Decrypt([]byte(passwd)); err != nil {
return errors.WrapMessage(err, "invalid password")
}
}
v.headers = mergeHeaders(v.headers, block.Header)
return nil
}
func (v *store) Sign(in io.Reader, out io.Writer) error {
if v.key == nil {
return errors.New("key is empty")
}
w, err := clearsign.Encode(out, v.key.PrivateKey, v.conf)
if err != nil {
return errors.WrapMessage(err, "init")
}
if _, err = io.Copy(w, in); err != nil {
return err
}
if err = w.Close(); err != nil {
return err
}
return nil
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
func generatePrivateKey(key *openpgp.Entity, w io.Writer, headers map[string]string) error {
enc, err := armor.Encode(w, openpgp.PrivateKeyType, headers)
if err != nil {
return errors.WrapMessage(err, "init armor encoder")
}
defer enc.Close() //nolint: errcheck
if err = key.SerializePrivate(enc, nil); err != nil {
return errors.WrapMessage(err, "serialize private key")
}
return nil
}
func generatePublicKey(key *openpgp.Entity, w io.Writer, headers map[string]string) error {
enc, err := armor.Encode(w, openpgp.PublicKeyType, headers)
if err != nil {
return errors.WrapMessage(err, "create OpenPGP armor")
}
defer enc.Close() //nolint: errcheck
if err = key.Serialize(enc); err != nil {
return errors.WrapMessage(err, "serialize public key")
}
return nil
}
func setupIdentities(key *openpgp.Entity, c *packet.Config) error {
// Sign all the identities
for _, id := range key.Identities {
id.SelfSignature.PreferredCompression = []uint8{1, 2, 3, 0}
id.SelfSignature.PreferredHash = []uint8{2, 8, 10, 1, 3, 9, 11}
id.SelfSignature.PreferredSymmetric = []uint8{9, 8, 7, 3, 2}
if err := id.SelfSignature.SignUserId(id.UserId.Id, key.PrimaryKey, key.PrivateKey, c); err != nil {
return err
}
}
return nil
}
func createHeaders(v []string) (map[string]string, error) {
if len(v)%2 != 0 {
return nil, errors.New("odd headers count")
}
result := make(map[string]string, len(v)/2)
for i := 0; i < len(v); i += 2 {
result[v[i]] = v[i+1]
}
return result, nil
}
func mergeHeaders(h ...map[string]string) map[string]string {
result := make(map[string]string)
for _, m := range h {
for k, v := range m {
result[k] = v
}
}
return result
}
func NewCert(c Config, hash crypto.Hash, bits int, headers ...string) (*Cert, error) {
h, err := createHeaders(headers)
if err != nil {
return nil, errors.WrapMessage(err, "parse headers")
}
conf := &packet.Config{
DefaultHash: hash,
RSABits: bits,
}
key, err := openpgp.NewEntity(c.Name, c.Comment, c.Email, conf)
if err != nil {
return nil, errors.WrapMessage(err, "generate entity")
}
if err = setupIdentities(key, conf); err != nil {
return nil, errors.WrapMessage(err, "setup entity")
}
var priv bytes.Buffer
if err = generatePrivateKey(key, &priv, h); err != nil {
return nil, errors.WrapMessage(err, "generate private key")
}
var pub bytes.Buffer
if err = generatePublicKey(key, &pub, h); err != nil {
return nil, errors.WrapMessage(err, "generate public key")
}
return &Cert{
Public: pub.Bytes(),
Private: priv.Bytes(),
}, nil
}
func NewCertSHA512(c Config, headers ...string) (*Cert, error) {
return NewCert(c, crypto.SHA512, 4096, headers...)
}