forked from decred/dcrd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
gencerts.go
347 lines (312 loc) · 8.43 KB
/
gencerts.go
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
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
// Copyright (c) 2020-2023 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package main
import (
"bytes"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"errors"
"fmt"
"io"
"math/big"
"net"
"os"
"time"
flags "github.com/jessevdk/go-flags"
)
func fatalf(format string, args ...interface{}) {
fmt.Fprintf(os.Stderr, format, args...)
os.Exit(1)
}
func usage(parser *flags.Parser) {
parser.WriteHelp(os.Stderr)
os.Exit(2)
}
type config struct {
CA string `short:"C" description:"sign generated certificate using CA cert (requires -K)"`
CAKey string `short:"K" description:"key of CA certificate"`
Hosts []string `short:"H" description:"hostname or IP certificate is valid for; may be specified multiple times"`
Local bool `short:"L" description:"append localhost, 127.0.0.1, and ::1 to hosts if not already specified"`
Org string `short:"o" description:"organization"`
Algo string `short:"a" description:"key algorithm (one of: P-256, P-384, P-521, Ed25519, RSA4096)"`
Years int `short:"y" description:"years certificate is valid for"`
Force bool `short:"f" description:"overwrite existing certs/keys"`
}
func main() {
cfg := config{
Algo: "P-256",
Years: 10,
Org: "gencerts",
}
parser := flags.NewParser(&cfg, flags.Default)
parser.Usage = "[OPTIONS] cert key"
args, err := parser.Parse()
if err != nil {
var e *flags.Error
if errors.As(err, &e) {
if e.Type != flags.ErrHelp {
os.Exit(1)
}
os.Exit(0)
}
os.Exit(1)
}
if len(args) != 2 {
usage(parser)
}
certname, keyname := args[0], args[1]
var keygen func() (pub, priv interface{})
switch cfg.Algo {
case "P-256":
keygen = ecKeyGen(elliptic.P256())
case "P-384":
keygen = ecKeyGen(elliptic.P384())
case "P-521":
keygen = ecKeyGen(elliptic.P521())
case "Ed25519":
keygen = ed25519KeyGen
case "RSA4096":
keygen = rsaKeyGen(4096)
default:
fmt.Fprintf(os.Stderr, "unknown algorithm %q\n", cfg.Algo)
usage(parser)
}
if cfg.CA == "" != (cfg.CAKey == "") {
fatalf("-C and -K must be used together\n")
}
if cfg.Local {
var localhost, v4Loopback, v6Loopback bool
for _, h := range cfg.Hosts {
switch h {
case "localhost":
localhost = true
case "127.0.0.1":
v4Loopback = true
case "::1":
v6Loopback = true
}
}
if !localhost {
cfg.Hosts = append(cfg.Hosts, "localhost")
}
if !v4Loopback {
cfg.Hosts = append(cfg.Hosts, "127.0.0.1")
}
if !v6Loopback {
cfg.Hosts = append(cfg.Hosts, "::1")
}
}
var cert *certWithPEM
pub, priv := keygen()
keyBlock, err := marshalPrivateKey(priv)
if err != nil {
fatalf("%s\n", err)
}
if cfg.CA == "" {
cert, err = generateAuthority(pub, priv, cfg.Hosts, cfg.Org, cfg.Years)
if err != nil {
fatalf("generate certificate authority: %v\n", err)
}
} else {
var ca *x509.Certificate
var caPriv interface{}
tlsCert, err := tls.LoadX509KeyPair(cfg.CA, cfg.CAKey)
if err != nil {
fatalf("open CA keypair: %s\n", err)
}
// will never error, as this was already parsed by LoadX509KeyPair
ca, _ = x509.ParseCertificate(tlsCert.Certificate[0])
caPriv = tlsCert.PrivateKey
cert, err = createIssuedCert(pub, caPriv, ca,
cfg.Hosts, cfg.Org, cfg.Years)
if err != nil {
fatalf("issue certificate: %v\n", err)
}
}
if !cfg.Force && fileExists(certname) {
fatalf("certificate file %q already exists\n", certname)
}
if !cfg.Force && fileExists(keyname) {
fatalf("key file %q already exists\n", keyname)
}
if err = os.WriteFile(certname, cert.PEMBlock, 0644); err != nil {
fatalf("cannot write cert: %v\n", err)
}
if err = os.WriteFile(keyname, keyBlock, 0600); err != nil {
os.Remove(certname)
fatalf("cannot write key: %v\n", err)
}
}
func fileExists(name string) bool {
if _, err := os.Stat(name); err != nil {
if os.IsNotExist(err) {
return false
}
}
return true
}
func ed25519KeyGen() (pub, priv interface{}) {
seed := make([]byte, ed25519.SeedSize)
_, err := io.ReadFull(rand.Reader, seed)
if err != nil {
fatalf("read random bytes: %v\n", err)
}
key := ed25519.NewKeyFromSeed(seed)
return key.Public(), key
}
func ecKeyGen(curve elliptic.Curve) func() (pub, priv interface{}) {
return func() (pub, priv interface{}) {
var key *ecdsa.PrivateKey
key, err := ecdsa.GenerateKey(curve, rand.Reader)
if err != nil {
fatalf("generate random EC key: %v\n", err)
}
return key.Public(), key
}
}
func rsaKeyGen(bits int) func() (pub, priv interface{}) {
return func() (pub, priv interface{}) {
var key *rsa.PrivateKey
key, err := rsa.GenerateKey(rand.Reader, bits)
if err != nil {
fatalf("generate random RSA key: %v\n", err)
}
return key.Public(), key
}
}
func randomX509SerialNumber() (*big.Int, error) {
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return nil, fmt.Errorf("failed to generate serial number: %w", err)
}
return serialNumber, nil
}
// End of ASN.1 time
var endOfTime = time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
type certWithPEM struct {
PEMBlock []byte
Cert *x509.Certificate
}
func newTemplate(hosts []string, org string, validUntil time.Time) (*x509.Certificate, error) {
now := time.Now()
if validUntil.After(endOfTime) {
validUntil = endOfTime
}
if validUntil.Before(now) {
return nil, fmt.Errorf("valid until date %v already elapsed", validUntil)
}
serialNumber, err := randomX509SerialNumber()
if err != nil {
return nil, err
}
cn := org
if len(hosts) > 0 {
cn = hosts[0]
}
var hostnames []string
var ips []net.IP
for _, h := range hosts {
if ip := net.ParseIP(h); ip != nil {
ips = append(ips, ip)
continue
}
hostnames = append(hostnames, h)
}
template := &x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
CommonName: cn,
Organization: []string{org},
},
NotBefore: now.Add(-time.Hour * 24),
NotAfter: validUntil,
DNSNames: hostnames,
IPAddresses: ips,
}
return template, nil
}
func generateAuthority(pub, priv interface{}, hosts []string, org string, years int) (*certWithPEM, error) {
validUntil := time.Now().Add(time.Hour * 24 * 365 * time.Duration(years))
template, err := newTemplate(hosts, org, validUntil)
if err != nil {
return nil, err
}
template.KeyUsage = x509.KeyUsageCertSign | x509.KeyUsageDigitalSignature
template.BasicConstraintsValid = true
template.IsCA = true
cert, err := x509.CreateCertificate(rand.Reader, template, template, pub, priv)
if err != nil {
return nil, err
}
buf := new(bytes.Buffer)
err = pem.Encode(buf, &pem.Block{Type: "CERTIFICATE", Bytes: cert})
if err != nil {
return nil, fmt.Errorf("failed to encode certificate: %w", err)
}
pemBlock := buf.Bytes()
x509Cert, err := x509.ParseCertificate(cert)
if err != nil {
return nil, err
}
ca := &certWithPEM{
PEMBlock: pemBlock,
Cert: x509Cert,
}
return ca, nil
}
func createIssuedCert(pub, caPriv interface{}, ca *x509.Certificate,
hosts []string, org string, years int) (*certWithPEM, error) {
if ca.KeyUsage&x509.KeyUsageCertSign == 0 {
return nil, fmt.Errorf("parent certificate cannot sign other certificates")
}
validUntil := time.Now().Add(time.Hour * 24 * 365 * time.Duration(years))
if validUntil.After(ca.NotAfter) {
validUntil = ca.NotAfter
}
template, err := newTemplate(hosts, org, validUntil)
if err != nil {
return nil, err
}
template.KeyUsage = x509.KeyUsageDigitalSignature
template.BasicConstraintsValid = true
cert, err := x509.CreateCertificate(rand.Reader, template, ca, pub, caPriv)
if err != nil {
return nil, err
}
buf := new(bytes.Buffer)
err = pem.Encode(buf, &pem.Block{Type: "CERTIFICATE", Bytes: cert})
if err != nil {
return nil, fmt.Errorf("failed to encode certificate: %w", err)
}
pemBlock := buf.Bytes()
x509Cert, err := x509.ParseCertificate(cert)
if err != nil {
return nil, err
}
issuedCert := &certWithPEM{
PEMBlock: pemBlock,
Cert: x509Cert,
}
return issuedCert, nil
}
func marshalPrivateKey(key interface{}) ([]byte, error) {
der, err := x509.MarshalPKCS8PrivateKey(key)
if err != nil {
return nil, fmt.Errorf("failed to marshal private key: %w", err)
}
buf := new(bytes.Buffer)
err = pem.Encode(buf, &pem.Block{Type: "PRIVATE KEY", Bytes: der})
if err != nil {
return nil, fmt.Errorf("failed to encode private key: %w", err)
}
return buf.Bytes(), nil
}