grpc/certs/certs.go

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package certs
import (
"bytes"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"math/big"
"net"
"time"
)
func New(host ...string) (tls.Certificate, error) {
priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return tls.Certificate{}, err
}
notBefore := time.Now()
notAfter := notBefore.Add(time.Hour * 24 * 365)
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return tls.Certificate{}, err
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{"Acme Co"},
},
NotBefore: notBefore,
NotAfter: notAfter,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
for _, h := range host {
if ip := net.ParseIP(h); ip != nil {
template.IPAddresses = append(template.IPAddresses, ip)
} else {
template.DNSNames = append(template.DNSNames, h)
}
}
template.IsCA = true
template.KeyUsage |= x509.KeyUsageCertSign
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
if err != nil {
return tls.Certificate{}, err
}
// create public key
certOut := bytes.NewBuffer(nil)
pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
// create private key
keyOut := bytes.NewBuffer(nil)
b, err := x509.MarshalECPrivateKey(priv)
if err != nil {
return tls.Certificate{}, err
}
pem.Encode(keyOut, &pem.Block{Type: "EC PRIVATE KEY", Bytes: b})
return tls.X509KeyPair(certOut.Bytes(), keyOut.Bytes())
}