From 9f81973580cc5d25d40930f64c74d80480949717 Mon Sep 17 00:00:00 2001
From: rasky <rasky@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Wed, 29 Sep 2010 16:36:14 +0000
Subject: [PATCH] SEC: Add Yarrow PRNG generator.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4360 38d2e660-2303-0410-9eaa-f027e97ec537
---
 bertos/sec/prng/yarrow.c | 119 +++++++++++++++++++++++++++++++++++++++
 bertos/sec/prng/yarrow.h |  60 ++++++++++++++++++++
 2 files changed, 179 insertions(+)
 create mode 100644 bertos/sec/prng/yarrow.c
 create mode 100644 bertos/sec/prng/yarrow.h

diff --git a/bertos/sec/prng/yarrow.c b/bertos/sec/prng/yarrow.c
new file mode 100644
index 00000000..8dbaf92f
--- /dev/null
+++ b/bertos/sec/prng/yarrow.c
@@ -0,0 +1,119 @@
+/**
+ * \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 Yarrow implementation
+ * \author Giovanni Bajo <rasky@develer.com>
+ *
+ */
+
+#include "yarrow.h"
+#include <sec/hash/sha1.h>
+#include <cfg/macros.h>
+#include <string.h>
+
+#define CONFIG_YARROW_GENERATOR_GATE             10
+
+static void yarrow_generate(PRNG *ctx_, uint8_t *data, size_t len)
+{
+	YarrowContext *ctx = (YarrowContext *)ctx_;
+	BlockCipher *cipher = 0;
+
+	ASSERT(len != 0);
+
+	do
+	{
+		if (ctx->lastidx == sizeof(ctx->last))
+		{
+			if (!cipher)
+			{
+				cipher = AES128_stackinit();
+				ASSERT(sizeof(ctx->counter) == cipher_block_len(cipher));
+				ASSERT(sizeof(ctx->curkey) == cipher_key_len(cipher));
+
+				cipher_set_key(cipher, ctx->curkey);
+				cipher_ctr_begin(cipher, ctx->counter);
+			}
+
+			cipher_ctr_step(cipher, ctx->last);
+
+			if (ctx->curkey_gencount == CONFIG_YARROW_GENERATOR_GATE)
+			{
+				ASSERT(cipher_block_len(cipher) == cipher_key_len(cipher));
+				cipher_set_key(cipher, ctx->last);
+				ctx->curkey_gencount = 0;
+				continue;
+			}
+
+			ctx->lastidx = 0;
+			ctx->curkey_gencount++;
+		}
+
+		int n = MIN(len, 16U-ctx->lastidx);
+		memcpy(data, ctx->last+ctx->lastidx, n);
+		data += n;
+		len -= n;
+		ctx->lastidx += n;
+	} while (len);
+}
+
+static void yarrow_reseed(PRNG *ctx_, const uint8_t *seed)
+{
+	YarrowContext *ctx = (YarrowContext *)ctx_;
+	Hash *h = SHA1_stackinit();
+
+	hash_begin(h);
+	hash_update(h, seed, ctx->prng.seed_len);
+	hash_update(h, ctx->curkey, sizeof(ctx->curkey));
+	memcpy(ctx->curkey, hash_final(h), sizeof(ctx->curkey));
+	kprintf("Yarrow reseeding:");
+	kdump(ctx->curkey, sizeof(ctx->curkey));
+
+	// Reset the counter for the sequence
+	memset(ctx->counter, 0, sizeof(ctx->counter));
+}
+
+
+/*********************************************************************/
+
+void yarrow_init(YarrowContext *ctx)
+{
+	ctx->prng.reseed = yarrow_reseed;
+	ctx->prng.generate = yarrow_generate;
+	ctx->prng.seed_len = 16;
+	ctx->prng.seeded = 0;
+
+	ctx->lastidx = sizeof(ctx->last);
+	ctx->curkey_gencount = 0;
+	memset(ctx->curkey, 0, sizeof(ctx->curkey));
+
+	ASSERT(sizeof(ctx->counter) == sizeof(ctx->last));
+}
diff --git a/bertos/sec/prng/yarrow.h b/bertos/sec/prng/yarrow.h
new file mode 100644
index 00000000..556d573f
--- /dev/null
+++ b/bertos/sec/prng/yarrow.h
@@ -0,0 +1,60 @@
+/**
+ * \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 Yarrow implementation
+ * \author Giovanni Bajo <rasky@develer.com>
+ *
+ */
+
+#ifndef SEC_PRNG_YARROW_H
+#define SEC_PRNG_YARROW_H
+
+#include <sec/prng.h>
+#include <sec/cipher/aes.h>
+
+typedef struct YarrowContext
+{
+	PRNG prng;
+
+	uint8_t counter[16];
+	uint8_t curkey[16];
+	uint8_t last[16];
+	uint8_t curkey_gencount;
+	uint8_t lastidx;
+} YarrowContext;
+
+void yarrow_init(YarrowContext *ctx);
+
+#define yarrow_stackinit(...) \
+	({ YarrowContext *ctx = alloca(sizeof(YarrowContext)); yarrow_init(ctx, ##__VA_ARGS__); &ctx->prng; })
+
+#endif /* SEC_PRNG_YARROW_H */
-- 
2.25.1