Patchwork [U-Boot,v7,1/5] tpm: add AUTH1 cmds for LoadKey2 and GetPubKey

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Submitter Dirk Eibach
Date June 26, 2013, 1:55 p.m.
Message ID <1372254917-8027-2-git-send-email-dirk.eibach@gdsys.cc>
Download mbox | patch
Permalink /patch/254751/
State Accepted, archived
Delegated to: Andy Fleming
Headers show

Comments

Dirk Eibach - June 26, 2013, 1:55 p.m.
From: Reinhard Pfau <pfau@gdsys.de>

Extend the tpm library with support for single authorized (AUTH1) commands
as specified in the TCG Main Specification 1.2. (The internally used helper
functions are implemented in a way that they could also be used for double
authorized commands if someone needs it.)

Provide enums with the return codes from the TCG Main specification.

For now only a single OIAP session is supported.

OIAP authorized version of the commands TPM_LoadKey2 and TPM_GetPubKey are
provided. Both features are available using the 'tpm' command, too.

Authorized commands are enabled with CONFIG_TPM_AUTH_SESSIONS. (Note that
this also requires CONFIG_SHA1 to be enabled.)

Signed-off-by: Reinhard Pfau <reinhard.pfau@gdsys.cc>
Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc>
Acked-by: Che-Liang Chiou <clchiou@chromium.org>
---
Changes in v7: None
Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3:
- fix email addresses

Changes in v2:
- replace some numeric constants with named constants
- style fixes (as shown by checkpatch.pl) in common/cmd_tpm.c and lib/tpm.c

 README           |  14 +++
 common/cmd_tpm.c | 100 ++++++++++++++++
 include/tpm.h    | 174 +++++++++++++++++++++++++++
 lib/tpm.c        | 351 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 638 insertions(+), 1 deletion(-)
Andy Fleming - July 16, 2013, 11:20 p.m.
On Wed, Jun 26, 2013 at 03:55:13PM +0200, Dirk Eibach wrote:
> From: Reinhard Pfau <pfau@gdsys.de>
> 
> Extend the tpm library with support for single authorized (AUTH1) commands
> as specified in the TCG Main Specification 1.2. (The internally used helper
> functions are implemented in a way that they could also be used for double
> authorized commands if someone needs it.)
> 
> Provide enums with the return codes from the TCG Main specification.
> 
> For now only a single OIAP session is supported.
> 
> OIAP authorized version of the commands TPM_LoadKey2 and TPM_GetPubKey are
> provided. Both features are available using the 'tpm' command, too.
> 
> Authorized commands are enabled with CONFIG_TPM_AUTH_SESSIONS. (Note that
> this also requires CONFIG_SHA1 to be enabled.)
> 
> Signed-off-by: Reinhard Pfau <reinhard.pfau@gdsys.cc>
> Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc>
> Acked-by: Che-Liang Chiou <clchiou@chromium.org>

Applied, thanks!

Andy

Patch

diff --git a/README b/README
index cd0336c..3f9a613 100644
--- a/README
+++ b/README
@@ -1234,6 +1234,20 @@  The following options need to be configured:
 			to. Contemporary x86 systems usually map it at
 			0xfed40000.
 
+		CONFIG_CMD_TPM
+		Add tpm monitor functions.
+		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
+		provides monitor access to authorized functions.
+
+		CONFIG_TPM
+		Define this to enable the TPM support library which provides
+		functional interfaces to some TPM commands.
+		Requires support for a TPM device.
+
+		CONFIG_TPM_AUTH_SESSIONS
+		Define this to enable authorized functions in the TPM library.
+		Requires CONFIG_TPM and CONFIG_SHA1.
+
 - USB Support:
 		At the moment only the UHCI host controller is
 		supported (PIP405, MIP405, MPC5200); define
diff --git a/common/cmd_tpm.c b/common/cmd_tpm.c
index 46fae18..c34000a 100644
--- a/common/cmd_tpm.c
+++ b/common/cmd_tpm.c
@@ -27,6 +27,13 @@ 
 #include <asm/unaligned.h>
 #include <linux/string.h>
 
+/* Useful constants */
+enum {
+	DIGEST_LENGTH		= 20,
+	/* max lengths, valid for RSA keys <= 2048 bits */
+	TPM_PUBKEY_MAX_LENGTH	= 288,
+};
+
 /**
  * Print a byte string in hexdecimal format, 16-bytes per line.
  *
@@ -546,6 +553,72 @@  static int do_tpm_nv_write(cmd_tbl_t *cmdtp, int flag,
 	return convert_return_code(err);
 }
 
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+
+static int do_tpm_oiap(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t auth_handle, err;
+
+	err = tpm_oiap(&auth_handle);
+
+	return convert_return_code(err);
+}
+
+static int do_tpm_load_key2_oiap(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t parent_handle, key_len, key_handle, err;
+	uint8_t usage_auth[DIGEST_LENGTH];
+	void *key;
+
+	if (argc < 5)
+		return CMD_RET_USAGE;
+
+	parent_handle = simple_strtoul(argv[1], NULL, 0);
+	key = (void *)simple_strtoul(argv[2], NULL, 0);
+	key_len = simple_strtoul(argv[3], NULL, 0);
+	if (strlen(argv[4]) != 2 * DIGEST_LENGTH)
+		return CMD_RET_FAILURE;
+	parse_byte_string(argv[4], usage_auth, NULL);
+
+	err = tpm_load_key2_oiap(parent_handle, key, key_len, usage_auth,
+			&key_handle);
+	if (!err)
+		printf("Key handle is 0x%x\n", key_handle);
+
+	return convert_return_code(err);
+}
+
+static int do_tpm_get_pub_key_oiap(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	uint32_t key_handle, err;
+	uint8_t usage_auth[DIGEST_LENGTH];
+	uint8_t pub_key_buffer[TPM_PUBKEY_MAX_LENGTH];
+	size_t pub_key_len = sizeof(pub_key_buffer);
+
+	if (argc < 3)
+		return CMD_RET_USAGE;
+
+	key_handle = simple_strtoul(argv[1], NULL, 0);
+	if (strlen(argv[2]) != 2 * DIGEST_LENGTH)
+		return CMD_RET_FAILURE;
+	parse_byte_string(argv[2], usage_auth, NULL);
+
+	err = tpm_get_pub_key_oiap(key_handle, usage_auth,
+			pub_key_buffer, &pub_key_len);
+	if (!err) {
+		printf("dump of received pub key structure:\n");
+		print_byte_string(pub_key_buffer, pub_key_len);
+	}
+	return convert_return_code(err);
+}
+
+TPM_COMMAND_NO_ARG(tpm_end_oiap)
+
+#endif /* CONFIG_TPM_AUTH_SESSIONS */
+
 #define MAKE_TPM_CMD_ENTRY(cmd) \
 	U_BOOT_CMD_MKENT(cmd, 0, 1, do_tpm_ ## cmd, "", "")
 
@@ -590,6 +663,16 @@  static cmd_tbl_t tpm_commands[] = {
 			do_tpm_nv_read, "", ""),
 	U_BOOT_CMD_MKENT(nv_write, 0, 1,
 			do_tpm_nv_write, "", ""),
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+	U_BOOT_CMD_MKENT(oiap, 0, 1,
+			 do_tpm_oiap, "", ""),
+	U_BOOT_CMD_MKENT(end_oiap, 0, 1,
+			 do_tpm_end_oiap, "", ""),
+	U_BOOT_CMD_MKENT(load_key2_oiap, 0, 1,
+			 do_tpm_load_key2_oiap, "", ""),
+	U_BOOT_CMD_MKENT(get_pub_key_oiap, 0, 1,
+			 do_tpm_get_pub_key_oiap, "", ""),
+#endif /* CONFIG_TPM_AUTH_SESSIONS */
 };
 
 static int do_tpm(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
@@ -638,6 +721,16 @@  U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm,
 "  get_capability cap_area sub_cap addr count\n"
 "    - Read <count> bytes of TPM capability indexed by <cap_area> and\n"
 "      <sub_cap> to memory address <addr>.\n"
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+"Storage functions\n"
+"  loadkey2_oiap parent_handle key_addr key_len usage_auth\n"
+"    - loads a key data from memory address <key_addr>, <key_len> bytes\n"
+"      into TPM using the parent key <parent_handle> with authorization\n"
+"      <usage_auth> (20 bytes hex string).\n"
+"  get_pub_key_oiap key_handle usage_auth\n"
+"    - get the public key portion of a loaded key <key_handle> using\n"
+"      authorization <usage auth> (20 bytes hex string)\n"
+#endif /* CONFIG_TPM_AUTH_SESSIONS */
 "Endorsement Key Handling Commands:\n"
 "  read_pubek addr count\n"
 "    - Read <count> bytes of the public endorsement key to memory\n"
@@ -648,6 +741,13 @@  U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm,
 "      <digest_hex_string>\n"
 "  pcr_read index addr count\n"
 "    - Read <count> bytes from PCR <index> to memory address <addr>.\n"
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+"Authorization Sessions\n"
+"  oiap\n"
+"    - setup an OIAP session\n"
+"  end_oiap\n"
+"    - terminates an active OIAP session\n"
+#endif /* CONFIG_TPM_AUTH_SESSIONS */
 "Non-volatile Storage Commands:\n"
 "  nv_define_space index permission size\n"
 "    - Establish a space at index <index> with <permission> of <size> bytes.\n"
diff --git a/include/tpm.h b/include/tpm.h
index 7219b73..5e9f832 100644
--- a/include/tpm.h
+++ b/include/tpm.h
@@ -1,5 +1,6 @@ 
 /*
  * Copyright (c) 2013 The Chromium OS Authors.
+ * Coypright (c) 2013 Guntermann & Drunck GmbH
  *
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -54,6 +55,120 @@  enum tpm_nv_index {
 };
 
 /**
+ * TPM return codes as defined in the TCG Main specification
+ * (TPM Main Part 2 Structures; Specification version 1.2)
+ */
+enum tpm_return_code {
+	TPM_BASE	= 0x00000000,
+	TPM_NON_FATAL	= 0x00000800,
+	TPM_SUCCESS	= TPM_BASE,
+	/* TPM-defined fatal error codes */
+	TPM_AUTHFAIL			= TPM_BASE +  1,
+	TPM_BADINDEX			= TPM_BASE +  2,
+	TPM_BAD_PARAMETER		= TPM_BASE +  3,
+	TPM_AUDITFAILURE		= TPM_BASE +  4,
+	TPM_CLEAR_DISABLED		= TPM_BASE +  5,
+	TPM_DEACTIVATED			= TPM_BASE +  6,
+	TPM_DISABLED			= TPM_BASE +  7,
+	TPM_DISABLED_CMD		= TPM_BASE +  8,
+	TPM_FAIL			= TPM_BASE +  9,
+	TPM_BAD_ORDINAL			= TPM_BASE + 10,
+	TPM_INSTALL_DISABLED		= TPM_BASE + 11,
+	TPM_INVALID_KEYHANDLE		= TPM_BASE + 12,
+	TPM_KEYNOTFOUND			= TPM_BASE + 13,
+	TPM_INAPPROPRIATE_ENC		= TPM_BASE + 14,
+	TPM_MIGRATE_FAIL		= TPM_BASE + 15,
+	TPM_INVALID_PCR_INFO		= TPM_BASE + 16,
+	TPM_NOSPACE			= TPM_BASE + 17,
+	TPM_NOSRK			= TPM_BASE + 18,
+	TPM_NOTSEALED_BLOB		= TPM_BASE + 19,
+	TPM_OWNER_SET			= TPM_BASE + 20,
+	TPM_RESOURCES			= TPM_BASE + 21,
+	TPM_SHORTRANDOM			= TPM_BASE + 22,
+	TPM_SIZE			= TPM_BASE + 23,
+	TPM_WRONGPCRVAL			= TPM_BASE + 24,
+	TPM_BAD_PARAM_SIZE		= TPM_BASE + 25,
+	TPM_SHA_THREAD			= TPM_BASE + 26,
+	TPM_SHA_ERROR			= TPM_BASE + 27,
+	TPM_FAILEDSELFTEST		= TPM_BASE + 28,
+	TPM_AUTH2FAIL			= TPM_BASE + 29,
+	TPM_BADTAG			= TPM_BASE + 30,
+	TPM_IOERROR			= TPM_BASE + 31,
+	TPM_ENCRYPT_ERROR		= TPM_BASE + 32,
+	TPM_DECRYPT_ERROR		= TPM_BASE + 33,
+	TPM_INVALID_AUTHHANDLE		= TPM_BASE + 34,
+	TPM_NO_ENDORSEMENT		= TPM_BASE + 35,
+	TPM_INVALID_KEYUSAGE		= TPM_BASE + 36,
+	TPM_WRONG_ENTITYTYPE		= TPM_BASE + 37,
+	TPM_INVALID_POSTINIT		= TPM_BASE + 38,
+	TPM_INAPPROPRIATE_SIG		= TPM_BASE + 39,
+	TPM_BAD_KEY_PROPERTY		= TPM_BASE + 40,
+	TPM_BAD_MIGRATION		= TPM_BASE + 41,
+	TPM_BAD_SCHEME			= TPM_BASE + 42,
+	TPM_BAD_DATASIZE		= TPM_BASE + 43,
+	TPM_BAD_MODE			= TPM_BASE + 44,
+	TPM_BAD_PRESENCE		= TPM_BASE + 45,
+	TPM_BAD_VERSION			= TPM_BASE + 46,
+	TPM_NO_WRAP_TRANSPORT		= TPM_BASE + 47,
+	TPM_AUDITFAIL_UNSUCCESSFUL	= TPM_BASE + 48,
+	TPM_AUDITFAIL_SUCCESSFUL	= TPM_BASE + 49,
+	TPM_NOTRESETABLE		= TPM_BASE + 50,
+	TPM_NOTLOCAL			= TPM_BASE + 51,
+	TPM_BAD_TYPE			= TPM_BASE + 52,
+	TPM_INVALID_RESOURCE		= TPM_BASE + 53,
+	TPM_NOTFIPS			= TPM_BASE + 54,
+	TPM_INVALID_FAMILY		= TPM_BASE + 55,
+	TPM_NO_NV_PERMISSION		= TPM_BASE + 56,
+	TPM_REQUIRES_SIGN		= TPM_BASE + 57,
+	TPM_KEY_NOTSUPPORTED		= TPM_BASE + 58,
+	TPM_AUTH_CONFLICT		= TPM_BASE + 59,
+	TPM_AREA_LOCKED			= TPM_BASE + 60,
+	TPM_BAD_LOCALITY		= TPM_BASE + 61,
+	TPM_READ_ONLY			= TPM_BASE + 62,
+	TPM_PER_NOWRITE			= TPM_BASE + 63,
+	TPM_FAMILY_COUNT		= TPM_BASE + 64,
+	TPM_WRITE_LOCKED		= TPM_BASE + 65,
+	TPM_BAD_ATTRIBUTES		= TPM_BASE + 66,
+	TPM_INVALID_STRUCTURE		= TPM_BASE + 67,
+	TPM_KEY_OWNER_CONTROL		= TPM_BASE + 68,
+	TPM_BAD_COUNTER			= TPM_BASE + 69,
+	TPM_NOT_FULLWRITE		= TPM_BASE + 70,
+	TPM_CONTEXT_GAP			= TPM_BASE + 71,
+	TPM_MAXNVWRITES			= TPM_BASE + 72,
+	TPM_NOOPERATOR			= TPM_BASE + 73,
+	TPM_RESOURCEMISSING		= TPM_BASE + 74,
+	TPM_DELEGATE_LOCK		= TPM_BASE + 75,
+	TPM_DELEGATE_FAMILY		= TPM_BASE + 76,
+	TPM_DELEGATE_ADMIN		= TPM_BASE + 77,
+	TPM_TRANSPORT_NOTEXCLUSIVE	= TPM_BASE + 78,
+	TPM_OWNER_CONTROL		= TPM_BASE + 79,
+	TPM_DAA_RESOURCES		= TPM_BASE + 80,
+	TPM_DAA_INPUT_DATA0		= TPM_BASE + 81,
+	TPM_DAA_INPUT_DATA1		= TPM_BASE + 82,
+	TPM_DAA_ISSUER_SETTINGS		= TPM_BASE + 83,
+	TPM_DAA_TPM_SETTINGS		= TPM_BASE + 84,
+	TPM_DAA_STAGE			= TPM_BASE + 85,
+	TPM_DAA_ISSUER_VALIDITY		= TPM_BASE + 86,
+	TPM_DAA_WRONG_W			= TPM_BASE + 87,
+	TPM_BAD_HANDLE			= TPM_BASE + 88,
+	TPM_BAD_DELEGATE		= TPM_BASE + 89,
+	TPM_BADCONTEXT			= TPM_BASE + 90,
+	TPM_TOOMANYCONTEXTS		= TPM_BASE + 91,
+	TPM_MA_TICKET_SIGNATURE		= TPM_BASE + 92,
+	TPM_MA_DESTINATION		= TPM_BASE + 93,
+	TPM_MA_SOURCE			= TPM_BASE + 94,
+	TPM_MA_AUTHORITY		= TPM_BASE + 95,
+	TPM_PERMANENTEK			= TPM_BASE + 97,
+	TPM_BAD_SIGNATURE		= TPM_BASE + 98,
+	TPM_NOCONTEXTSPACE		= TPM_BASE + 99,
+	/* TPM-defined non-fatal errors */
+	TPM_RETRY		= TPM_BASE + TPM_NON_FATAL,
+	TPM_NEEDS_SELFTEST	= TPM_BASE + TPM_NON_FATAL + 1,
+	TPM_DOING_SELFTEST	= TPM_BASE + TPM_NON_FATAL + 2,
+	TPM_DEFEND_LOCK_RUNNING	= TPM_BASE + TPM_NON_FATAL + 3,
+};
+
+/**
  * Initialize TPM device.  It must be called before any TPM commands.
  *
  * @return 0 on success, non-0 on error.
@@ -201,4 +316,63 @@  uint32_t tpm_physical_set_deactivated(uint8_t state);
 uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap,
 		void *cap, size_t count);
 
+/**
+ * Issue a TPM_FlushSpecific command for a AUTH ressource.
+ *
+ * @param auth_handle	handle of the auth session
+ * @return return code of the operation
+ */
+uint32_t tpm_terminate_auth_session(uint32_t auth_handle);
+
+/**
+ * Issue a TPM_OIAP command to setup an object independant authorization
+ * session.
+ * Information about the session is stored internally.
+ * If there was already an OIAP session active it is terminated and a new
+ * session is set up.
+ *
+ * @param auth_handle	pointer to the (new) auth handle or NULL.
+ * @return return code of the operation
+ */
+uint32_t tpm_oiap(uint32_t *auth_handle);
+
+/**
+ * Ends an active OIAP session.
+ *
+ * @return return code of the operation
+ */
+uint32_t tpm_end_oiap(void);
+
+/**
+ * Issue a TPM_LoadKey2 (Auth1) command using an OIAP session for authenticating
+ * the usage of the parent key.
+ *
+ * @param parent_handle	handle of the parent key.
+ * @param key		pointer to the key structure (TPM_KEY or TPM_KEY12).
+ * @param key_length	size of the key structure
+ * @param parent_key_usage_auth	usage auth for the parent key
+ * @param key_handle	pointer to the key handle
+ * @return return code of the operation
+ */
+uint32_t tpm_load_key2_oiap(uint32_t parent_handle,
+		const void *key, size_t key_length,
+		const void *parent_key_usage_auth,
+		uint32_t *key_handle);
+
+/**
+ * Issue a TPM_GetPubKey (Auth1) command using an OIAP session for
+ * authenticating the usage of the key.
+ *
+ * @param key_handle	handle of the key
+ * @param usage_auth	usage auth for the key
+ * @param pubkey	pointer to the pub key buffer; may be NULL if the pubkey
+ *			should not be stored.
+ * @param pubkey_len	pointer to the pub key buffer len. On entry: the size of
+ *			the provided pubkey buffer. On successful exit: the size
+ *			of the stored TPM_PUBKEY structure (iff pubkey != NULL).
+ * @return return code of the operation
+ */
+uint32_t tpm_get_pub_key_oiap(uint32_t key_handle, const void *usage_auth,
+		void *pubkey, size_t *pubkey_len);
+
 #endif /* __TPM_H */
diff --git a/lib/tpm.c b/lib/tpm.c
index 42c9bea..f0b4f59 100644
--- a/lib/tpm.c
+++ b/lib/tpm.c
@@ -1,5 +1,6 @@ 
 /*
  * Copyright (c) 2013 The Chromium OS Authors.
+ * Coypright (c) 2013 Guntermann & Drunck GmbH
  *
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -22,6 +23,7 @@ 
 
 #include <common.h>
 #include <stdarg.h>
+#include <sha1.h>
 #include <tpm.h>
 #include <asm/unaligned.h>
 
@@ -35,8 +37,31 @@  enum {
 	TPM_REQUEST_HEADER_LENGTH	= 10,
 	TPM_RESPONSE_HEADER_LENGTH	= 10,
 	PCR_DIGEST_LENGTH		= 20,
+	DIGEST_LENGTH			= 20,
+	TPM_REQUEST_AUTH_LENGTH		= 45,
+	TPM_RESPONSE_AUTH_LENGTH	= 41,
+	/* some max lengths, valid for RSA keys <= 2048 bits */
+	TPM_KEY12_MAX_LENGTH		= 618,
+	TPM_PUBKEY_MAX_LENGTH		= 288,
 };
 
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+
+#ifndef CONFIG_SHA1
+#error "TPM_AUTH_SESSIONS require SHA1 to be configured, too"
+#endif /* !CONFIG_SHA1 */
+
+struct session_data {
+	int		valid;
+	uint32_t	handle;
+	uint8_t		nonce_even[DIGEST_LENGTH];
+	uint8_t		nonce_odd[DIGEST_LENGTH];
+};
+
+static struct session_data oiap_session = {0, };
+
+#endif /* CONFIG_TPM_AUTH_SESSIONS */
+
 /**
  * Pack data into a byte string.  The data types are specified in
  * the format string: 'b' means unsigned byte, 'w' unsigned word,
@@ -235,7 +260,7 @@  static uint32_t tpm_sendrecv_command(const void *command,
 			response, &response_length);
 	if (err)
 		return TPM_LIB_ERROR;
-	if (response)
+	if (size_ptr)
 		*size_ptr = response_length;
 
 	return tpm_return_code(response);
@@ -579,3 +604,327 @@  uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap,
 
 	return 0;
 }
+
+#ifdef CONFIG_TPM_AUTH_SESSIONS
+
+/**
+ * Fill an authentication block in a request.
+ * This func can create the first as well as the second auth block (for
+ * double authorized commands).
+ *
+ * @param request	pointer to the request (w/ uninitialised auth data)
+ * @param request_len0	length of the request without auth data
+ * @param handles_len	length of the handles area in request
+ * @param auth_session	pointer to the (valid) auth session to be used
+ * @param request_auth	pointer to the auth block of the request to be filled
+ * @param auth		authentication data (HMAC key)
+ */
+static uint32_t create_request_auth(const void *request, size_t request_len0,
+	size_t handles_len,
+	struct session_data *auth_session,
+	void *request_auth, const void *auth)
+{
+	uint8_t hmac_data[DIGEST_LENGTH * 3 + 1];
+	sha1_context hash_ctx;
+	const size_t command_code_offset = 6;
+	const size_t auth_nonce_odd_offset = 4;
+	const size_t auth_continue_offset = 24;
+	const size_t auth_auth_offset = 25;
+
+	if (!auth_session || !auth_session->valid)
+		return TPM_LIB_ERROR;
+
+	sha1_starts(&hash_ctx);
+	sha1_update(&hash_ctx, request + command_code_offset, 4);
+	if (request_len0 > TPM_REQUEST_HEADER_LENGTH + handles_len)
+		sha1_update(&hash_ctx,
+			    request + TPM_REQUEST_HEADER_LENGTH + handles_len,
+			    request_len0 - TPM_REQUEST_HEADER_LENGTH
+			    - handles_len);
+	sha1_finish(&hash_ctx, hmac_data);
+
+	sha1_starts(&hash_ctx);
+	sha1_update(&hash_ctx, auth_session->nonce_odd, DIGEST_LENGTH);
+	sha1_update(&hash_ctx, hmac_data, sizeof(hmac_data));
+	sha1_finish(&hash_ctx, auth_session->nonce_odd);
+
+	if (pack_byte_string(request_auth, TPM_REQUEST_AUTH_LENGTH, "dsb",
+			     0, auth_session->handle,
+			     auth_nonce_odd_offset, auth_session->nonce_odd,
+			     DIGEST_LENGTH,
+			     auth_continue_offset, 1))
+		return TPM_LIB_ERROR;
+	if (pack_byte_string(hmac_data, sizeof(hmac_data), "ss",
+			     DIGEST_LENGTH,
+			     auth_session->nonce_even,
+			     DIGEST_LENGTH,
+			     2 * DIGEST_LENGTH,
+			     request_auth + auth_nonce_odd_offset,
+			     DIGEST_LENGTH + 1))
+		return TPM_LIB_ERROR;
+	sha1_hmac(auth, DIGEST_LENGTH, hmac_data, sizeof(hmac_data),
+		  request_auth + auth_auth_offset);
+
+	return TPM_SUCCESS;
+}
+
+/**
+ * Verify an authentication block in a response.
+ * Since this func updates the nonce_even in the session data it has to be
+ * called when receiving a succesfull AUTH response.
+ * This func can verify the first as well as the second auth block (for
+ * double authorized commands).
+ *
+ * @param command_code	command code of the request
+ * @param response	pointer to the request (w/ uninitialised auth data)
+ * @param handles_len	length of the handles area in response
+ * @param auth_session	pointer to the (valid) auth session to be used
+ * @param response_auth	pointer to the auth block of the response to be verified
+ * @param auth		authentication data (HMAC key)
+ */
+static uint32_t verify_response_auth(uint32_t command_code,
+	const void *response, size_t response_len0,
+	size_t handles_len,
+	struct session_data *auth_session,
+	const void *response_auth, const void *auth)
+{
+	uint8_t hmac_data[DIGEST_LENGTH * 3 + 1];
+	uint8_t computed_auth[DIGEST_LENGTH];
+	sha1_context hash_ctx;
+	const size_t return_code_offset = 6;
+	const size_t auth_continue_offset = 20;
+	const size_t auth_auth_offset = 21;
+	uint8_t auth_continue;
+
+	if (!auth_session || !auth_session->valid)
+		return TPM_AUTHFAIL;
+	if (pack_byte_string(hmac_data, sizeof(hmac_data), "d",
+			     0, command_code))
+		return TPM_LIB_ERROR;
+	if (response_len0 < TPM_RESPONSE_HEADER_LENGTH)
+		return TPM_LIB_ERROR;
+
+	sha1_starts(&hash_ctx);
+	sha1_update(&hash_ctx, response + return_code_offset, 4);
+	sha1_update(&hash_ctx, hmac_data, 4);
+	if (response_len0 > TPM_RESPONSE_HEADER_LENGTH + handles_len)
+		sha1_update(&hash_ctx,
+			    response + TPM_RESPONSE_HEADER_LENGTH + handles_len,
+			    response_len0 - TPM_RESPONSE_HEADER_LENGTH
+			    - handles_len);
+	sha1_finish(&hash_ctx, hmac_data);
+
+	memcpy(auth_session->nonce_even, response_auth, DIGEST_LENGTH);
+	auth_continue = ((uint8_t *)response_auth)[auth_continue_offset];
+	if (pack_byte_string(hmac_data, sizeof(hmac_data), "ssb",
+			     DIGEST_LENGTH,
+			     response_auth,
+			     DIGEST_LENGTH,
+			     2 * DIGEST_LENGTH,
+			     auth_session->nonce_odd,
+			     DIGEST_LENGTH,
+			     3 * DIGEST_LENGTH,
+			     auth_continue))
+		return TPM_LIB_ERROR;
+
+	sha1_hmac(auth, DIGEST_LENGTH, hmac_data, sizeof(hmac_data),
+		  computed_auth);
+
+	if (memcmp(computed_auth, response_auth + auth_auth_offset,
+		   DIGEST_LENGTH))
+		return TPM_AUTHFAIL;
+
+	return TPM_SUCCESS;
+}
+
+
+uint32_t tpm_terminate_auth_session(uint32_t auth_handle)
+{
+	const uint8_t command[18] = {
+		0x00, 0xc1,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x00,	/* parameter size */
+		0x00, 0x00, 0x00, 0xba,	/* TPM_COMMAND_CODE */
+		0x00, 0x00, 0x00, 0x00,	/* TPM_HANDLE */
+		0x00, 0x00, 0x00, 0x02,	/* TPM_RESSOURCE_TYPE */
+	};
+	const size_t req_handle_offset = TPM_REQUEST_HEADER_LENGTH;
+	uint8_t request[COMMAND_BUFFER_SIZE];
+
+	if (pack_byte_string(request, sizeof(request), "sd",
+			     0, command, sizeof(command),
+			     req_handle_offset, auth_handle))
+		return TPM_LIB_ERROR;
+	if (oiap_session.valid && oiap_session.handle == auth_handle)
+		oiap_session.valid = 0;
+
+	return tpm_sendrecv_command(request, NULL, NULL);
+}
+
+uint32_t tpm_end_oiap(void)
+{
+	uint32_t err = TPM_SUCCESS;
+	if (oiap_session.valid)
+		err = tpm_terminate_auth_session(oiap_session.handle);
+	return err;
+}
+
+uint32_t tpm_oiap(uint32_t *auth_handle)
+{
+	const uint8_t command[10] = {
+		0x00, 0xc1,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x0a,	/* parameter size */
+		0x00, 0x00, 0x00, 0x0a,	/* TPM_COMMAND_CODE */
+	};
+	const size_t res_auth_handle_offset = TPM_RESPONSE_HEADER_LENGTH;
+	const size_t res_nonce_even_offset = TPM_RESPONSE_HEADER_LENGTH + 4;
+	uint8_t response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (oiap_session.valid)
+		tpm_terminate_auth_session(oiap_session.handle);
+
+	err = tpm_sendrecv_command(command, response, &response_length);
+	if (err)
+		return err;
+	if (unpack_byte_string(response, response_length, "ds",
+			       res_auth_handle_offset, &oiap_session.handle,
+			       res_nonce_even_offset, &oiap_session.nonce_even,
+			       (uint32_t)DIGEST_LENGTH))
+		return TPM_LIB_ERROR;
+	oiap_session.valid = 1;
+	if (auth_handle)
+		*auth_handle = oiap_session.handle;
+	return 0;
+}
+
+uint32_t tpm_load_key2_oiap(uint32_t parent_handle,
+		const void *key, size_t key_length,
+		const void *parent_key_usage_auth,
+		uint32_t *key_handle)
+{
+	const uint8_t command[14] = {
+		0x00, 0xc2,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x00,	/* parameter size */
+		0x00, 0x00, 0x00, 0x41,	/* TPM_COMMAND_CODE */
+		0x00, 0x00, 0x00, 0x00,	/* parent handle */
+	};
+	const size_t req_size_offset = 2;
+	const size_t req_parent_handle_offset = TPM_REQUEST_HEADER_LENGTH;
+	const size_t req_key_offset = TPM_REQUEST_HEADER_LENGTH + 4;
+	const size_t res_handle_offset = TPM_RESPONSE_HEADER_LENGTH;
+	uint8_t request[sizeof(command) + TPM_KEY12_MAX_LENGTH
+			+ TPM_REQUEST_AUTH_LENGTH];
+	uint8_t response[COMMAND_BUFFER_SIZE];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (!oiap_session.valid) {
+		err = tpm_oiap(NULL);
+		if (err)
+			return err;
+	}
+	if (pack_byte_string(request, sizeof(request), "sdds",
+			     0, command, sizeof(command),
+			     req_size_offset,
+			     sizeof(command) + key_length
+			     + TPM_REQUEST_AUTH_LENGTH,
+			     req_parent_handle_offset, parent_handle,
+			     req_key_offset, key, key_length
+		))
+		return TPM_LIB_ERROR;
+
+	err = create_request_auth(request, sizeof(command) + key_length, 4,
+				&oiap_session,
+				request + sizeof(command) + key_length,
+				parent_key_usage_auth);
+	if (err)
+		return err;
+	err = tpm_sendrecv_command(request, response, &response_length);
+	if (err) {
+		if (err == TPM_AUTHFAIL)
+			oiap_session.valid = 0;
+		return err;
+	}
+
+	err = verify_response_auth(0x00000041, response,
+			response_length - TPM_RESPONSE_AUTH_LENGTH,
+			4, &oiap_session,
+			response + response_length - TPM_RESPONSE_AUTH_LENGTH,
+			parent_key_usage_auth);
+	if (err)
+		return err;
+
+	if (key_handle) {
+		if (unpack_byte_string(response, response_length, "d",
+				       res_handle_offset, key_handle))
+			return TPM_LIB_ERROR;
+	}
+
+	return 0;
+}
+
+uint32_t tpm_get_pub_key_oiap(uint32_t key_handle, const void *usage_auth,
+			void *pubkey, size_t *pubkey_len)
+{
+	const uint8_t command[14] = {
+		0x00, 0xc2,		/* TPM_TAG */
+		0x00, 0x00, 0x00, 0x00,	/* parameter size */
+		0x00, 0x00, 0x00, 0x21,	/* TPM_COMMAND_CODE */
+		0x00, 0x00, 0x00, 0x00,	/* key handle */
+	};
+	const size_t req_size_offset = 2;
+	const size_t req_key_handle_offset = TPM_REQUEST_HEADER_LENGTH;
+	const size_t res_pubkey_offset = TPM_RESPONSE_HEADER_LENGTH;
+	uint8_t request[sizeof(command) + TPM_REQUEST_AUTH_LENGTH];
+	uint8_t response[TPM_RESPONSE_HEADER_LENGTH + TPM_PUBKEY_MAX_LENGTH
+			+ TPM_RESPONSE_AUTH_LENGTH];
+	size_t response_length = sizeof(response);
+	uint32_t err;
+
+	if (!oiap_session.valid) {
+		err = tpm_oiap(NULL);
+		if (err)
+			return err;
+	}
+	if (pack_byte_string(request, sizeof(request), "sdd",
+			     0, command, sizeof(command),
+			     req_size_offset,
+			     (uint32_t)(sizeof(command)
+			     + TPM_REQUEST_AUTH_LENGTH),
+			     req_key_handle_offset, key_handle
+		))
+		return TPM_LIB_ERROR;
+	err = create_request_auth(request, sizeof(command), 4, &oiap_session,
+			request + sizeof(command), usage_auth);
+	if (err)
+		return err;
+	err = tpm_sendrecv_command(request, response, &response_length);
+	if (err) {
+		if (err == TPM_AUTHFAIL)
+			oiap_session.valid = 0;
+		return err;
+	}
+	err = verify_response_auth(0x00000021, response,
+			response_length - TPM_RESPONSE_AUTH_LENGTH,
+			0, &oiap_session,
+			response + response_length - TPM_RESPONSE_AUTH_LENGTH,
+			usage_auth);
+	if (err)
+		return err;
+
+	if (pubkey) {
+		if ((response_length - TPM_RESPONSE_HEADER_LENGTH
+			- TPM_RESPONSE_AUTH_LENGTH) > *pubkey_len)
+			return TPM_LIB_ERROR;
+		*pubkey_len = response_length - TPM_RESPONSE_HEADER_LENGTH
+			- TPM_RESPONSE_AUTH_LENGTH;
+		memcpy(pubkey, response + res_pubkey_offset,
+		       response_length - TPM_RESPONSE_HEADER_LENGTH
+		       - TPM_RESPONSE_AUTH_LENGTH);
+	}
+
+	return 0;
+}
+
+#endif /* CONFIG_TPM_AUTH_SESSIONS */