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
|
package main
import (
"bytes"
"crypto/x509"
"encoding/pem"
"fmt"
"io"
"os"
"strings"
"github.com/github/smimesign/certstore"
cms "github.com/github/smimesign/ietf-cms"
"github.com/pkg/errors"
)
func commandSign() error {
userIdent, err := findUserIdentity()
if err != nil {
return errors.Wrap(err, "failed to get identity matching specified user-id")
}
if userIdent == nil {
return fmt.Errorf("could not find identity matching specified user-id: %s", *localUserOpt)
}
// Git is looking for "\n[GNUPG:] SIG_CREATED ", meaning we need to print a
// line before SIG_CREATED. BEGIN_SIGNING seems appropraite. GPG emits this,
// though GPGSM does not.
sBeginSigning.emit()
cert, err := userIdent.Certificate()
if err != nil {
return errors.Wrap(err, "failed to get idenity certificate")
}
signer, err := userIdent.Signer()
if err != nil {
return errors.Wrap(err, "failed to get idenity signer")
}
var f io.ReadCloser
if len(fileArgs) == 1 {
if f, err = os.Open(fileArgs[0]); err != nil {
return errors.Wrapf(err, "failed to open message file (%s)", fileArgs[0])
}
defer f.Close()
} else {
f = stdin
}
dataBuf := new(bytes.Buffer)
if _, err = io.Copy(dataBuf, f); err != nil {
return errors.Wrap(err, "failed to read message from stdin")
}
sd, err := cms.NewSignedData(dataBuf.Bytes())
if err != nil {
return errors.Wrap(err, "failed to create signed data")
}
if err = sd.Sign([]*x509.Certificate{cert}, signer); err != nil {
return errors.Wrap(err, "failed to sign message")
}
if *detachSignFlag {
sd.Detached()
}
if len(*tsaOpt) > 0 {
if err = sd.AddTimestamps(*tsaOpt); err != nil {
return errors.Wrap(err, "failed to add timestamp")
}
}
chain, err := userIdent.CertificateChain()
if err != nil {
return errors.Wrap(err, "failed to get idenity certificate chain")
}
if chain, err = certsForSignature(chain); err != nil {
return err
}
if err = sd.SetCertificates(chain); err != nil {
return errors.Wrap(err, "failed to set certificates")
}
der, err := sd.ToDER()
if err != nil {
return errors.Wrap(err, "failed to serialize signature")
}
emitSigCreated(cert, *detachSignFlag)
if *armorFlag {
err = pem.Encode(stdout, &pem.Block{
Type: "SIGNED MESSAGE",
Bytes: der,
})
} else {
_, err = stdout.Write(der)
}
if err != nil {
return errors.New("failed to write signature")
}
return nil
}
// findUserIdentity attempts to find an identity to sign with in the certstore
// by checking available identities against the --local-user argument.
func findUserIdentity() (certstore.Identity, error) {
var (
email string
fpr []byte
)
if strings.ContainsRune(*localUserOpt, '@') {
email = normalizeEmail(*localUserOpt)
} else {
fpr = normalizeFingerprint(*localUserOpt)
}
if len(email) == 0 && len(fpr) == 0 {
return nil, fmt.Errorf("bad user-id format: %s", *localUserOpt)
}
for _, ident := range idents {
if cert, err := ident.Certificate(); err == nil && (certHasEmail(cert, email) || certHasFingerprint(cert, fpr)) {
return ident, nil
}
}
return nil, nil
}
// certsForSignature determines which certificates to include in the signature
// based on the --include-certs option specified by the user.
func certsForSignature(chain []*x509.Certificate) ([]*x509.Certificate, error) {
include := *includeCertsOpt
if include < -3 {
include = -2 // default
}
if include > len(chain) {
include = len(chain)
}
switch include {
case -3:
for i := len(chain) - 1; i > 0; i-- {
issuer, cert := chain[i], chain[i-1]
// remove issuer when cert has AIA extension
if bytes.Equal(issuer.RawSubject, cert.RawIssuer) && len(cert.IssuingCertificateURL) > 0 {
chain = chain[0:i]
}
}
return chainWithoutRoot(chain), nil
case -2:
return chainWithoutRoot(chain), nil
case -1:
return chain, nil
default:
return chain[0:include], nil
}
}
// Returns the provided chain, having removed the root certificate, if present.
// This includes removing the cert itself if the chain is a single self-signed
// cert.
func chainWithoutRoot(chain []*x509.Certificate) []*x509.Certificate {
if len(chain) == 0 {
return chain
}
lastIdx := len(chain) - 1
last := chain[lastIdx]
if bytes.Equal(last.RawIssuer, last.RawSubject) {
return chain[0:lastIdx]
}
return chain
}
|
