diff --git a/sexp-transport-format.c b/sexp-transport-format.c
new file mode 100644
index 0000000000000000000000000000000000000000..feb685dcd15adf39e496f9c5e71dd25f8cef458a
--- /dev/null
+++ b/sexp-transport-format.c
@@ -0,0 +1,84 @@
+/* sexp-transport-format.c
+ *
+ * Writing s-expressions in transport format.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2002 Niels Möller
+ *  
+ * The nettle library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ * 
+ * The nettle library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+ * License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#include "sexp.h"
+
+#include "base64.h"
+#include "buffer.h"
+
+unsigned
+sexp_transport_vformat(struct nettle_buffer *buffer,
+		       const char *format, va_list args)
+{
+  unsigned start = 0;
+  unsigned length;
+  unsigned base64_length;
+
+  if (buffer)
+    {
+      if (!NETTLE_BUFFER_PUTC(buffer, '{'))
+	return 0;
+
+      start = buffer->size;
+    }
+  
+  length = sexp_vformat(buffer, format, args);
+
+  if (!length)
+    return 0;
+
+  base64_length = BASE64_ENCODE_RAW_LENGTH(length);
+
+  if (buffer)
+    {
+      /* FIXME: This assumes that data is never removed from the
+       * buffer. That works for the current buffer, but it would be
+       * nice to get rid of this restriction. */
+      if (!nettle_buffer_space(buffer, base64_length - length))
+	return 0;
+
+      base64_encode_raw(buffer->contents + start,
+			length, buffer->contents + start);
+      
+      if (!NETTLE_BUFFER_PUTC(buffer, '}'))
+	return 0;
+    }
+  
+  return base64_length + 2;
+}
+
+unsigned
+sexp_transport_format(struct nettle_buffer *buffer,
+		      const char *format, ...)
+{
+  unsigned done;
+  va_list args;
+
+  va_start(args, format);
+  done = sexp_transport_vformat(buffer, format, args);
+  va_end(args);
+  
+  return done;
+}