Golang crypto/x509.CertPool.AddCert() and Subjects functions example

package crypto/x509

AddCert adds a certificate to a pool.

Golang crypto/x509.CertPool.AddCert() function usage example

  package main

  import (
 "time"
 "math/big"
 "crypto/x509"
 "crypto/x509/pkix"
 "fmt"
 "crypto/rsa"
 "crypto/rand"
  )

  func main() {

 // ok, lets populate the certificate with some data
 // not all fields in Certificate will be populated
 // see Certificate structure at
 // http://golang.org/pkg/crypto/x509/#Certificate
 template := &x509.Certificate {
 IsCA : true,
 BasicConstraintsValid : true,
 SubjectKeyId : []byte{1,2,3},
 SerialNumber : big.NewInt(1234),
 Subject : pkix.Name{
 Country : []string{"Earth"},
 Organization: []string{"Mother Nature"},
 },
 NotBefore : time.Now(),
 NotAfter : time.Now().AddDate(5,5,5),
 // see http://golang.org/pkg/crypto/x509/#KeyUsage
 ExtKeyUsage : []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
 KeyUsage : x509.KeyUsageDigitalSignature|x509.KeyUsageCertSign,
 }

 // generate private key
 privatekey, err := rsa.GenerateKey(rand.Reader, 2048)

 if err != nil {
 fmt.Println(err)
 }

 publickey := &privatekey.PublicKey

 // create a self-signed certificate. template = parent
 var parent = template
 cert, err := x509.CreateCertificate(rand.Reader, template, parent, publickey,privatekey)

 if err != nil {
 fmt.Println(err)
 }

 roots := x509.NewCertPool()

 certs, err := x509.ParseCertificates(cert)

 if err != nil {
 fmt.Println(err)
 }

 fmt.Println("BEFORE AddCert")

 fmt.Println(roots)

 for i := range certs {
 roots.AddCert(certs[i])
 }

 fmt.Println("AFTER AddCert")
 fmt.Println(roots)

 if len(roots.Subjects()) != 1 {
 fmt.Println("Expecting a cert! ")
 }
 fmt.Printf("Pool Subjects : %x\n", roots.Subjects())
 }

Output :

BEFORE AddCert

&{map[] map[] []}

AFTER AddCert

&{map[:[0]] map[0(10 UEarth10U Mother Nature:[0]] [0xc208017b00]}

Pool Subjects : [3028310e300c06035504061305456172746831163014060355040a130d4d6f74686572204e6174757265]

Reference :

http://golang.org/pkg/crypto/x509/#CertPool.AddCert

http://golang.org/pkg/crypto/x509/#CertPool.Subjects