Add cookie session store helper

session/gorilla/cookie.go

@@ -0,0 +1,32 @@
+package gorilla
+
+import (
+	"crypto/rand"
+
+	"github.com/gorilla/sessions"
+	"github.com/pkg/errors"
+)
+
+// CreateCookieSessionStore creates and returns a new cookie session store
+// with random authentication and encryption keys
+func CreateCookieSessionStore(authKeySize, encryptKeySize int) (sessions.Store, error) {
+	authenticationKey, err := generateRandomBytes(64)
+	if err != nil {
+		return nil, errors.Wrap(err, "error while generating cookie authentication key")
+	}
+	encryptionKey, err := generateRandomBytes(32)
+	if err != nil {
+		return nil, errors.Wrap(err, "error while generating cookie encryption key")
+	}
+	store := sessions.NewCookieStore(authenticationKey, encryptionKey)
+	return store, nil
+}
+
+func generateRandomBytes(n int) ([]byte, error) {
+	b := make([]byte, n)
+	_, err := rand.Read(b)
+	if err != nil {
+		return nil, err
+	}
+	return b, nil
+}