diff --git a/pkg/ca/ca.go b/pkg/ca/ca.go
new file mode 100644
index 0000000..8c4b9a3
--- /dev/null
+++ b/pkg/ca/ca.go
@@ -0,0 +1,28 @@
+package ca
+
+import (
+	"crypto/x509"
+	"math/big"
+	"time"
+
+	"gitlab.com/urkob/go-cert-gen/pkg/client"
+)
+
+type CaSubject struct {
+	Organization string
+	CommonName   string
+}
+
+type CaConfig struct {
+	SerialNumber *big.Int
+	Subject      CaSubject
+	KeyUsage     x509.KeyUsage
+	ExtKeyUsage  []x509.ExtKeyUsage
+	Duration     time.Duration
+}
+
+type RootCACertificateIface interface {
+	WithClientCert(config *client.ClientCertConfig) (client.ClientCertIface, error)
+	Key() []byte
+	PEM() []byte
+}