"failed to find any PEM data in certificate input" error popup by tls.X509KeyPair

I am trying to make are tls cert for HTTPS server by golang x509 package

and i got this error

> tls: failed to find any PEM data in certificate input

After some research, I create my Cert like this

func Generatecert()  {
ca := &x509.Certificate{
SerialNumber: big.NewInt(2023),
Subject: pkix.Name{
Organization:       []string{"Company"},
OrganizationalUnit: []string{"lol"},
Country:            []string{"US"},
Province:           []string{""},
Locality:           []string{"NY"},
StreetAddress:      []string{"No street"},
PostalCode:         []string{"77777"},
},
NotBefore:             time.Now(),
NotAfter:              time.Now().AddDate(10, 0, 0),
SubjectKeyId:          []byte{1, 2, 3, 4, 5},
BasicConstraintsValid: true,
IsCA:                  true,
ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
}
certpubl, certpriv, err := ed25519.GenerateKey(rand.Reader)
if err != nil {
log.Println("key generate failed", err)
return
}
certCert, err := x509.CreateCertificate(rand.Reader, ca, ca, certpubl, certpriv)
if err != nil {
log.Println("create cert failed", err)
return
}
out := &bytes.Buffer{}
//Encoding cert
certtestpem := &pem.Block{Type: "CERTIFICATE", Bytes: certCert}
pem.Encode(out, certtestpem)
publicCert := out.Bytes()
certDERBlock, publicCert := pem.Decode(publicCert)
//Check Decoded cert
print(certDERBlock.Type, "\n")
if publicCert != nil {
print("publicCert nil\n")
}
//Encoding Private Key
out.Reset()
privatepem, _ := x509.MarshalPKCS8PrivateKey(certpriv)
pem.Encode(out, &pem.Block{Type: "PRIVATE KEY", Bytes: privatepem})
privitKey := out.Bytes()
//check KeyPair
_, err = tls.X509KeyPair(publicCert, privitKey)
if err != nil {
print(err.Error())
}
}

it show the error like under

> CERTIFICATE
>
> publicCert nil
>
> tls: failed to find any PEM data in certificate input

I try Decode after pem.EncodeToMemory

the pem.Type are correct, but variable "publicCert" is nil, And I try add are \n begin of the cert, it did nothing, but the cert itself is not nil, Can Somebody Help me with this

What sould I do to make a working Tls???

after some debug, it seem like the pem.Encode function not working for me,

so i change it to pem.EncodeToMemory and it working thank you for the help.

There are several problems in this code

> publicCert := out.Bytes()

Checking the content of publicCert at this stage shows the expect value. But the following statement will simply overwrite publicCert:

> certDERBlock, publicCert := pem.Decode(publicCert)

This can be seen by checking publicCert after this statement. As documented publicCert will now show the data after the actual certificate.

It should be instead

certDERBlock, _ := pem.Decode(publicCert)

Checking the content of publicCert after this corrected statement shows the expected value again.

> out.Reset()
> privatepem, _ := x509.MarshalPKCS8PrivateKey(certpriv)
> pem.Encode(out, &pem.Block{Type: "PRIVATE KEY", Bytes: privatepem})
> privitKey := out.Bytes()

This will get the expected value into privitKey. But, it will change publicCert since it is just a slice of out and out has been changed the the operations. Thus out will now contain at the beginning the privitKey and no longer the start of the certificate - and this is reflected in the value of publicCert.

See also the documentation for bytes.Buffer.Bytes

> The slice is valid for use only until the next buffer modification (that is, only until the next call to a method like Read, Write, Reset, or Truncate)

So instead of just resetting the existing buffer

> out.Reset()

it would be better to create a new buffer for privitKey and keep the existing one for publicCert

> out = &bytes.Buffer{}