Introducing Tls apis in Arduino Core api

Added Interfaces to handle Tls api standardization in arduino core api.

Author: andreagilardoni

api/Tls.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include "Client.h"
+
+
+namespace arduino {
+
+// Tls CertificatesKeys are strings 
+using CertificateKey = const char[];
+
+enum class CertificateFormat {
+    Der,
+    Pem,
+}
+
+class Tls: public ClientConnect {
+public:
+    virtual ~Tls() = default;
+
+    enum IdentityVerification {
+        MTls,       // both ends identity needs to be verified
+        Tls,        // The server side end is verified against CA
+        Insecure,   // no check against server side identity
+    };
+
+    virtual void setIdentityVerification(IdentityVerification mode) { _mode = mode; };
+    virtual void setCA(CertificateKey ca, CertificateFormat f=CertificateFormat::Pem) = 0;
+    virtual void setCertificate(CertificateKey public, CertificateKey private, CertificateFormat f=CertificateFormat::Pem) = 0;
+
+
+    // Tls protocol enables Server Name Indication usage, for which a client provides
+    // the hostname it is trying to connect to. This hostname may be required to be verified
+    // against the server provided one
+    virtual void sniVerification(bool) = 0;
+
+    // manually provide an hostname that will be used toghether with sni
+    // if connect is called with hostname as parameter this will be automatically called
+    virtual void setHostname(const char hostname[]) = 0;
+protected:
+    IdentityVerification _mode;
+};
+
+class TlsClient: public Client, Tls {
+
+};
+}