bettercap/tls/sign.go

89 lines
2 KiB
Go

package tls
import (
"crypto/rsa"
"crypto/sha1"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"math/big"
"net"
"sort"
"time"
"github.com/elazarl/goproxy"
)
func hashSorted(lst []string) []byte {
c := make([]string, len(lst))
copy(c, lst)
sort.Strings(c)
h := sha1.New()
for _, s := range c {
h.Write([]byte(s + ","))
}
return h.Sum(nil)
}
func hashSortedBigInt(lst []string) *big.Int {
rv := new(big.Int)
rv.SetBytes(hashSorted(lst))
return rv
}
func SignCertificateForHost(ca *tls.Certificate, host string) (cert *tls.Certificate, err error) {
var x509ca *x509.Certificate
// TODO: read actual fields from the host
if x509ca, err = x509.ParseCertificate(ca.Certificate[0]); err != nil {
return
}
start := time.Unix(0, 0)
end, err := time.Parse("2006-01-02", "2049-12-31")
if err != nil {
panic(err)
}
hosts := []string{host}
hash := hashSorted(hosts)
serial := new(big.Int)
serial.SetBytes(hash)
template := x509.Certificate{
SerialNumber: serial,
Issuer: x509ca.Subject,
Subject: pkix.Name{
Organization: []string{"Cisco Systems, Inc."},
},
NotBefore: start,
NotAfter: end,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
for _, h := range hosts {
if ip := net.ParseIP(h); ip != nil {
template.IPAddresses = append(template.IPAddresses, ip)
} else {
template.DNSNames = append(template.DNSNames, h)
}
}
var csprng goproxy.CounterEncryptorRand
if csprng, err = goproxy.NewCounterEncryptorRandFromKey(ca.PrivateKey, hash); err != nil {
return
}
var certpriv *rsa.PrivateKey
if certpriv, err = rsa.GenerateKey(&csprng, 1024); err != nil {
return
}
var derBytes []byte
if derBytes, err = x509.CreateCertificate(&csprng, &template, x509ca, &certpriv.PublicKey, ca.PrivateKey); err != nil {
return
}
return &tls.Certificate{
Certificate: [][]byte{derBytes, ca.Certificate[0]},
PrivateKey: certpriv,
}, nil
}