From 8871b496c28accb79030bf395c3258b3d04bcf60 Mon Sep 17 00:00:00 2001
From: hasufell <hasufell@hasufell.de>
Date: Fri, 30 May 2014 19:23:45 +0200
Subject: [PATCH] KEYGEN: support import/export of keys

---
 src/keypair.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/keypair.h |  50 ++++++++++++++++++++++++
 2 files changed, 154 insertions(+)

diff --git a/src/keypair.c b/src/keypair.c
index b7eb23c..f47c056 100644
--- a/src/keypair.c
+++ b/src/keypair.c
@@ -26,14 +26,18 @@
  * @brief key creation and operations
  */
 
+#include "ascii_poly.h"
 #include "context.h"
+#include "file.h"
 #include "keypair.h"
+#include "ntru_string.h"
 #include "poly.h"
 
 #include <fmpz_poly.h>
 #include <fmpz.h>
 
 #include <stdbool.h>
+#include <string.h>
 
 
 /*------------------------------------------------------------------------*/
@@ -87,6 +91,106 @@ _return:
 
 /*------------------------------------------------------------------------*/
 
+void
+export_public_key(char const * const filename,
+		fmpz_poly_t pub,
+		ntru_context *ctx)
+{
+	string *pub_string;
+
+	pub_string = poly_to_base64(pub, ctx);
+	write_file(pub_string, filename);
+
+	string_delete(pub_string);
+}
+
+/*------------------------------------------------------------------------*/
+
+void
+export_priv_key(char const * const filename,
+		fmpz_poly_t priv,
+		ntru_context *ctx)
+{
+	string *priv_string;
+	fmpz_poly_t priv_u;
+
+	fmpz_poly_init(priv_u);
+	fmpz_poly_set(priv_u, priv);
+	fmpz_poly_mod_unsigned(priv_u, ctx->p);
+
+	priv_string = poly_to_base64(priv_u, ctx);
+	write_file(priv_string, filename);
+
+	string_delete(priv_string);
+}
+
+/*------------------------------------------------------------------------*/
+
+void
+import_public_key(char const * const filename,
+		fmpz_poly_t pub,
+		ntru_context *ctx)
+{
+	string *pub_string;
+	fmpz_poly_t **imported;
+
+	pub_string = read_file(filename);
+	imported = base64_to_poly_arr(pub_string, ctx);
+
+	/* if the array exceeds one element, then something
+	 * went horribly wrong */
+	if (*imported[1])
+		NTRU_ABORT("Failed importing public key!\n");
+
+	fmpz_poly_set(pub, **imported);
+
+	string_delete(pub_string);
+	poly_delete(**imported);
+	free(imported);
+}
+
+/*------------------------------------------------------------------------*/
+
+void
+import_priv_key(char const * const filename,
+		fmpz_poly_t priv,
+		fmpz_poly_t priv_inv,
+		ntru_context *ctx)
+{
+	string *pub_string;
+	fmpz_poly_t **imported,
+				Fp;
+
+	fmpz_poly_init(Fp);
+
+	pub_string = read_file(filename);
+
+	imported = base64_to_poly_arr(pub_string, ctx);
+	fmpz_poly_mod(**imported, ctx->p);
+
+	/* if the array exceeds one element, then something
+	 * went horribly wrong */
+	if (*imported[1])
+		NTRU_ABORT("Failed importing public key!\n");
+
+	fmpz_poly_set(priv, **imported);
+
+	if (!poly_inverse_poly_p(priv, Fp, ctx))
+		goto cleanup;
+
+	fmpz_poly_mod(Fp, ctx->p);
+
+	fmpz_poly_set(priv_inv, Fp);
+	fmpz_poly_clear(Fp);
+
+cleanup:
+	string_delete(pub_string);
+	poly_delete(**imported);
+	free(imported);
+}
+
+/*------------------------------------------------------------------------*/
+
 void
 ntru_delete_keypair(keypair *pair)
 {
diff --git a/src/keypair.h b/src/keypair.h
index 307e65f..46926e6 100644
--- a/src/keypair.h
+++ b/src/keypair.h
@@ -79,6 +79,56 @@ ntru_create_keypair(
 		keypair *pair,
 		ntru_context *ctx);
 
+/**
+ * Export the public key to a file.
+ *
+ * @param filename the file to save the public key into
+ * @param pub the public key
+ * @param ctx the NTRU context
+ */
+void
+export_public_key(char const * const filename,
+		fmpz_poly_t pub,
+		ntru_context *ctx);
+
+/**
+ * Export the private key to a file.
+ *
+ * @param filename the file to save the private key into
+ * @param priv the private key
+ * @param ctx the NTRU context
+ */
+void
+export_priv_key(char const * const filename,
+		fmpz_poly_t priv,
+		ntru_context *ctx);
+
+/**
+ * Import the public key from a file.
+ * @param filename the file to get the public key from
+ * @param pub where to save the public key [out]
+ * @param ctx the NTRU context
+ */
+void
+import_public_key(char const * const filename,
+		fmpz_poly_t pub,
+		ntru_context *ctx);
+
+/**
+ * Import the private key from a file and store him
+ * along with his inverse.
+ *
+ * @param filename the file to get the private key from
+ * @param priv where to save the private key [out]
+ * @param priv_inv where to save the inverse of the private key [out]
+ * @param ctx the NTRU context
+ */
+void
+import_priv_key(char const * const filename,
+		fmpz_poly_t priv,
+		fmpz_poly_t priv_inv,
+		ntru_context *ctx);
+
 /**
  * Used to free the inner structure
  * of a keypair. This will not call free()