diff --git a/rsa2sexp.c b/rsa2sexp.c
new file mode 100644
index 0000000000000000000000000000000000000000..9a087cae052583a2c82e92a6a8b227939eff5eab
--- /dev/null
+++ b/rsa2sexp.c
@@ -0,0 +1,52 @@
+/* rsa2sexp.c
+ *
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2002 Niels M�ller
+ *  
+ * 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.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if HAVE_LIBGMP
+
+#include "rsa.h"
+
+#include "sexp.h"
+
+int
+rsa_keypair_to_sexp(struct nettle_buffer *buffer,
+		    const struct rsa_public_key *pub,
+		    const struct rsa_private_key *priv)
+{
+  if (priv)
+    return sexp_format(buffer,
+		       "(%s(%s(%s%b)(%s%b)(%s%b)"
+		       "(%s%b)(%s%b)(%s%b)(%s%b)(%s%b)))",
+		       "private-key", "rsa", "n", pub->n, "e", pub->e,
+		       "d", priv->d, "p", priv->p, "q", priv->q,
+		       "a", priv->a, "b", priv->b, "c", priv->c);
+  else
+    return sexp_format(buffer, "(%s(%s(%s%b)(%s%b)))",
+		       "public-key", "rsa", "n", pub->n, "e", pub->e);
+}
+
+#endif /* HAVE_LIBGMP */
diff --git a/sexp2rsa.c b/sexp2rsa.c
new file mode 100644
index 0000000000000000000000000000000000000000..1027765a4363152bb131f852e803313b85b83d50
--- /dev/null
+++ b/sexp2rsa.c
@@ -0,0 +1,116 @@
+/* sexp2rsa.h
+ *
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2002 Niels M�ller
+ *  
+ * 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.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if HAVE_LIBGMP
+
+#include "rsa.h"
+
+#include "bignum.h"
+#include "sexp.h"
+
+#include <string.h>
+
+static int
+get_value(mpz_t x, struct sexp_iterator *i)
+{
+  if (sexp_iterator_next(i)
+      && i->type == SEXP_ATOM
+      && !i->display)
+    {
+      nettle_mpz_set_str_256(x, i->atom_length, i->atom);
+      return 1;
+    }
+  else
+    return 0;
+}
+
+#define GET(x, v) do { if (!get_value(x, v)) return 0; } while(0)
+
+int
+rsa_keypair_from_sexp(struct rsa_public_key *pub,
+		      struct rsa_private_key *priv,
+		      unsigned length, const uint8_t *expr)
+{
+  struct sexp_iterator i;
+
+  static const uint8_t *inner[8]
+    = { "n", "e", "d", "p", "q", "a", "b", "c" };
+  static const uint8_t *names[3]
+    = { "rsa", "rsa-pkcs1", "rsa-pkcs1-sha1" };
+  const uint8_t *outer;
+  struct sexp_iterator values[8];
+  unsigned nvalues;
+  
+  sexp_iterator_init(&i, length, expr);
+
+  if (!sexp_iterator_next(&i))
+    return 0;
+  
+  if (priv)
+    {
+      outer = "private-key";
+      nvalues = 8;
+    }
+  else
+    {
+      outer = "public-key";
+      nvalues = 2;
+    }
+
+  if (!sexp_iterator_check_type(&i, outer))
+    return 0;
+
+  if (!sexp_iterator_next(&i))
+    return 0;
+
+  if (!sexp_iterator_check_types(&i, 3, names))
+    return 0;
+  
+  if (!sexp_iterator_assoc(&i, nvalues, inner, values))
+    return 0;
+
+  if (priv)
+    {
+      GET(priv->d, &values[2]);
+      GET(priv->p, &values[3]);
+      GET(priv->q, &values[4]);
+      GET(priv->a, &values[5]);
+      GET(priv->b, &values[6]);
+      GET(priv->c, &values[7]);
+    }
+
+  if (pub)
+    {
+      GET(pub->n, &values[0]);
+      GET(pub->e, &values[1]);
+    }
+    
+  return 1;
+}
+
+#endif /* HAVE_LIBGMP */