* Add X509 functions and example from Silvio Clecio to generate private key

git-svn-id: trunk@40800 -

.gitattributes

@@ -3833,6 +3833,7 @@ packages/gnome1/src/zvt/lists.inc svneol=native#text/plain
 packages/gnome1/src/zvt/vt.inc svneol=native#text/plain
 packages/gnome1/src/zvt/vtx.inc svneol=native#text/plain
 packages/gnutls/examples/httpget.pp svneol=native#text/plain
+packages/gnutls/examples/privkey.pp svneol=native#text/plain
 packages/gnutls/examples/testgnutls.pp svneol=native#text/plain
 packages/gnutls/fpmake.pp svneol=native#text/plain
 packages/gnutls/src/gnutls.pp svneol=native#text/plain

packages/gnutls/examples/privkey.pp

@@ -0,0 +1,67 @@
+{
+  Simple Low-level example showing how to generate a
+  RSA private key (4096 bytes) using the GnuTLS binding.
+
+  Author: Silvio Clecio (silvioprog)
+  Date: Mon Jan  7 01:36:18 -03 2019
+  GnuTLS version: 3.4+
+}
+
+program privkey;
+
+{$MODE OBJFPC}{$H+}
+{$ASSERTIONS ON}
+
+uses
+  sysutils,
+  ctypes,
+  gnutls;
+
+type
+{  cchar = Byte;
+  Pcchar = PAnsiChar;
+  Pcsize_t = PNativeUInt;
+  Pcvoid = Pointer;}
+
+  EGnuTLS = Exception;
+
+
+procedure CheckRet(ret: cint);
+var
+  P: Pchar;
+  S: string;
+begin
+  if ret = GNUTLS_E_SUCCESS then
+    Exit;
+  P := gnutls_strerror(ret);
+  S:=StrPas(P);// SetString(S, @P[0], Length(Pcchar(@P[0])));
+  SetCodePage(RawByteString(S), CP_UTF8, False);
+  raise EGnuTLS.Create(S);
+end;
+
+var
+  priv_key: String;
+  priv_key_size: cuint = SizeOf(priv_key);
+  key: Tgnutls_x509_privkey_t;
+  
+begin
+  LoadGnuTLS;
+  try
+    Assert(GnuTLSLoaded);
+    try
+      CheckRet(gnutls_x509_privkey_init(@key));
+      priv_key_size := gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_HIGH);
+      setLength(Priv_key,priv_key_size*2);
+      CheckRet(gnutls_x509_privkey_generate(key, GNUTLS_PK_RSA, priv_key_size, 0));
+      CheckRet(gnutls_x509_privkey_export(key, GNUTLS_X509_FMT_PEM, @priv_key[1], @priv_key_size));
+      setLength(Priv_key,priv_key_size);
+
+      WriteLn(priv_key);
+    except
+      gnutls_x509_privkey_deinit(key);
+      raise;
+    end;
+  finally
+    FreeGnuTLS;
+  end;
+end.