created a pts_pcr class for PCR computations

2012-07-20 14:57:28 +02:00
parent cfa69fce13
commit 5a6c18853e
4 changed files with 287 additions and 55 deletions
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2012 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+#include "pts_pcr.h"
+
+#include <debug.h>
+
+/**
+ * Maximum number of PCR's of TPM, TPM Spec 1.2
+ */
+#define PCR_MAX_NUM				24
+
+/**
+ * Number of bytes that can be saved in a PCR of TPM, TPM Spec 1.2
+ */
+#define PCR_LEN					20
+
+typedef struct private_pts_pcr_t private_pts_pcr_t;
+
+/**
+ * Private data of a pts_pcr_t object.
+ *
+ */
+struct private_pts_pcr_t {
+
+	/**
+	 * Public pts_pcr_t interface.
+	 */
+	pts_pcr_t public;
+
+	/**
+	 * Shadow PCR registers
+	 */
+	chunk_t pcrs[PCR_MAX_NUM];
+
+	/**
+	 * Hasher used to extend shadow PCRs
+	 */
+	hasher_t *hasher;
+
+};
+
+METHOD(pts_pcr_t, get, chunk_t,
+	private_pts_pcr_t *this, u_int32_t pcr)
+{
+	return (pcr < PCR_MAX_NUM) ? this->pcrs[pcr] : chunk_empty;
+}
+
+METHOD(pts_pcr_t, set, void,
+	private_pts_pcr_t *this, u_int32_t pcr, chunk_t value)
+{
+	if (pcr < PCR_MAX_NUM && value.len == PCR_LEN)
+	{
+		memcpy(this->pcrs[pcr].ptr, value.ptr, PCR_LEN);
+	}
+}
+
+METHOD(pts_pcr_t, extend, chunk_t,
+	private_pts_pcr_t *this, u_int32_t pcr, chunk_t measurement)
+{
+	if (pcr >= PCR_MAX_NUM || measurement.len != PCR_LEN)
+	{
+		DBG1(DBG_PTS, "PCR%d does not exist or has the wrong size", pcr);
+		return chunk_empty;
+	}
+	if (!this->hasher->get_hash(this->hasher, this->pcrs[pcr] , NULL) ||
+		!this->hasher->get_hash(this->hasher, measurement, this->pcrs[pcr].ptr))
+	{
+		DBG1(DBG_PTS, "PCR%d was not extended due to a hasher problem", pcr);
+		return chunk_empty;
+	}
+	return this->pcrs[pcr];
+}
+
+METHOD(pts_pcr_t, destroy, void,
+	private_pts_pcr_t *this)
+{
+	u_int32_t i;
+
+	for (i = 0; i < PCR_MAX_NUM; i++)
+	{
+		free(this->pcrs[i].ptr);
+	}
+	this->hasher->destroy(this->hasher);
+	free(this);
+}
+
+/**
+ * See header
+ */
+pts_pcr_t *pts_pcr_create(void)
+{
+	private_pts_pcr_t *this;
+	hasher_t *hasher;
+	u_int32_t i;
+
+	hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
+	if (!hasher)
+	{
+		DBG1(DBG_PTS, "%N hasher could not be created",
+			 hash_algorithm_short_names, HASH_SHA1);
+		return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.get = _get,
+			.set = _set,
+			.extend = _extend,
+			.destroy = _destroy,
+		},
+		.hasher = hasher,
+	);
+
+	for (i = 0; i < PCR_MAX_NUM; i++)
+	{
+		this->pcrs[i] = chunk_alloc(PCR_LEN);
+		memset(this->pcrs[i].ptr, 0x00, PCR_LEN);
+	}
+
+	return &this->public;
+}
+