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cert_generator.go
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/
cert_generator.go
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package initializer
import (
"bytes"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"github.com/crossplane/crossplane-runtime/pkg/errors"
)
const (
errGenerateCertificate = "cannot generate tls certificate"
)
// CertificateSigner is the parent's certificate and key that will be used to sign the certificate
type CertificateSigner struct {
certificate *x509.Certificate
key *rsa.PrivateKey
certificatePEM []byte
}
// CertificateGenerator can return you TLS certificate valid for given domains.
type CertificateGenerator interface {
Generate(*x509.Certificate, *CertificateSigner) (key []byte, crt []byte, err error)
}
var (
pkixName = pkix.Name{
CommonName: "Crossplane",
Organization: []string{"Crossplane"},
Country: []string{"Earth"},
Province: []string{"Earth"},
Locality: []string{"Earth"},
}
)
// NewCertGenerator returns a new CertGenerator.
func NewCertGenerator() *CertGenerator {
return &CertGenerator{}
}
// CertGenerator generates a root CA and key that can be used by client and
// servers.
type CertGenerator struct{}
// Generate creates TLS Secret with 10 years expiration date that is valid
// for the given domains.
func (*CertGenerator) Generate(cert *x509.Certificate, signer *CertificateSigner) (key []byte, crt []byte, err error) {
// NOTE(muvaf): Why 2048 and not 4096? Mainly performance.
// See https://www.fastly.com/blog/key-size-for-tls
privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, nil, errors.Wrap(err, "cannot generate private key")
}
if signer == nil {
signer = &CertificateSigner{
certificate: cert,
key: privateKey,
}
}
certBytes, err := x509.CreateCertificate(rand.Reader, cert, signer.certificate, &privateKey.PublicKey, signer.key)
if err != nil {
return nil, nil, errors.Wrap(err, "cannot create certificate with key")
}
certPEM := new(bytes.Buffer)
if err := pem.Encode(certPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: certBytes,
}); err != nil {
return nil, nil, errors.Wrap(err, "cannot encode cert into PEM")
}
certKeyPEM := new(bytes.Buffer)
if err := pem.Encode(certKeyPEM, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
}); err != nil {
return nil, nil, errors.Wrap(err, "cannot encode private key into PEM")
}
return certKeyPEM.Bytes(), certPEM.Bytes(), nil
}