From: rasky <rasky@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Fri, 24 Sep 2010 16:23:12 +0000 (+0000)
Subject: SEC: add generic interface for key-derivation functions.
X-Git-Tag: 2.6.0~97
X-Git-Url: https://codewiz.org/gitweb?a=commitdiff_plain;h=4ec9559a050632e54a74bb9179c2efe56e926070;p=bertos.git

SEC: add generic interface for key-derivation functions.


git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4304 38d2e660-2303-0410-9eaa-f027e97ec537
---

diff --git a/bertos/sec/kdf.h b/bertos/sec/kdf.h
new file mode 100644
index 00000000..48ae1c74
--- /dev/null
+++ b/bertos/sec/kdf.h
@@ -0,0 +1,95 @@
+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2010 Develer S.r.l. (http://www.develer.com/)
+ *
+ * -->
+ *
+ * \brief Generic interface for key derivation functions.
+ * \author Giovanni Bajo <rasky@develer.com>
+ * 
+ */
+
+#ifndef SEC_KDF_H
+#define SEC_KDF_H
+
+#include <cfg/compiler.h>
+#include <cfg/macros.h>
+#include <cfg/debug.h>
+#include <string.h>
+
+typedef struct Kdf
+{
+	const uint8_t* block;
+	size_t block_len;
+	size_t to_read;
+		
+	void (*begin)(struct Kdf *kdf, const char *pwd, size_t pwd_len,
+				  const uint8_t *salt, size_t salt_len);
+	void (*next)(struct Kdf *kdf);
+} Kdf;
+
+/**
+ * Initialize the key derivation function, with the specified \a password and \a salt.
+ */
+INLINE void kdf_begin(Kdf *kdf, const char *pwd, size_t pwd_len,
+					  const uint8_t *salt, size_t salt_len)
+{
+	ASSERT(kdf->begin);
+	kdf->begin(kdf, pwd, pwd_len, salt, salt_len);
+}
+
+/**
+ * Extract \a len derived bytes into the \a out buffer.
+ * 
+ * After having initialized the derivation function iwth \a kdf_begin, you can call
+ * this function multiple times, to produce several batches of derived data.
+ * 
+ * \note Some algorithms implementing this API might have a maximum length of bytes
+ * that can be derived, after which they will simply ASSERT().
+ */
+INLINE void kdf_read(Kdf *kdf, uint8_t *out, size_t len)
+{
+	do
+	{
+		if (kdf->to_read == 0)
+		{
+			kdf->next(kdf);
+			ASSERT(kdf->to_read != 0);
+		}
+
+		size_t c = MIN(len, kdf->to_read);
+		memcpy(out, kdf->block, c);
+		len -= c;
+		out += c;
+		kdf->block += c;
+		kdf->to_read -= c;
+	} while (len);
+}
+
+#endif /* SEC_KDF_H */