lbcutil/certgen.go
2014-08-30 15:10:29 -05:00

129 lines
3.2 KiB
Go

// Copyright (c) 2013-2014 Conformal Systems LLC.
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package btcutil
import (
"bytes"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
_ "crypto/sha512" // Needed for RegisterHash in init
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"errors"
"fmt"
"math/big"
"net"
"os"
"time"
)
// NewTLSCertPair returns a new PEM-encoded x.509 certificate pair
// based on a 521-bit ECDSA private key. The machine's local interface
// addresses and all variants of IPv4 and IPv6 localhost are included as
// valid IP addresses.
func NewTLSCertPair(organization string, validUntil time.Time, extraHosts []string) (cert, key []byte, err error) {
now := time.Now()
if validUntil.Before(now) {
return nil, nil, errors.New("validUntil would create an already-expired certificate")
}
priv, err := ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
if err != nil {
return nil, nil, err
}
// end of ASN.1 time
endOfTime := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
if validUntil.After(endOfTime) {
validUntil = endOfTime
}
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return nil, nil, fmt.Errorf("failed to generate serial number: %s", err)
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{organization},
},
NotBefore: now.Add(-time.Hour * 24),
NotAfter: validUntil,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature |
x509.KeyUsageCertSign,
IsCA: true, // so can sign self.
BasicConstraintsValid: true,
}
host, err := os.Hostname()
if err != nil {
return nil, nil, err
}
// Use maps to prevent adding duplicates.
ipAddresses := map[string]net.IP{
"127.0.0.1": net.ParseIP("127.0.0.1"),
"::1": net.ParseIP("::1"),
}
dnsNames := map[string]bool{
host: true,
"localhost": true,
}
addrs, err := interfaceAddrs()
if err != nil {
return nil, nil, err
}
for _, a := range addrs {
ip, _, err := net.ParseCIDR(a.String())
if err == nil {
ipAddresses[ip.String()] = ip
}
}
for _, hostStr := range extraHosts {
host, _, err := net.SplitHostPort(hostStr)
if err != nil {
host = hostStr
}
if ip := net.ParseIP(host); ip != nil {
ipAddresses[ip.String()] = ip
} else {
dnsNames[host] = true
}
}
template.DNSNames = make([]string, 0, len(dnsNames))
for dnsName := range dnsNames {
template.DNSNames = append(template.DNSNames, dnsName)
}
template.IPAddresses = make([]net.IP, 0, len(ipAddresses))
for _, ip := range ipAddresses {
template.IPAddresses = append(template.IPAddresses, ip)
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template,
&template, &priv.PublicKey, priv)
if err != nil {
return nil, nil, fmt.Errorf("failed to create certificate: %v\n", err)
}
certBuf := &bytes.Buffer{}
pem.Encode(certBuf, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
keybytes, err := x509.MarshalECPrivateKey(priv)
if err != nil {
return nil, nil, err
}
keyBuf := &bytes.Buffer{}
pem.Encode(keyBuf, &pem.Block{Type: "EC PRIVATE KEY", Bytes: keybytes})
return certBuf.Bytes(), keyBuf.Bytes(), nil
}