]> git.kernelconcepts.de Git - karo-tx-uboot.git/commitdiff
tpm: add AUTH1 cmds for LoadKey2 and GetPubKey
authorReinhard Pfau <pfau@gdsys.de>
Wed, 26 Jun 2013 13:55:13 +0000 (15:55 +0200)
committerAndy Fleming <afleming@freescale.com>
Tue, 16 Jul 2013 22:44:29 +0000 (17:44 -0500)
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>
Signed-off-by: Andy Fleming <afleming@freescale.com>
README
common/cmd_tpm.c
include/tpm.h
lib/tpm.c

diff --git a/README b/README
index 33b5728abc6bd2cfb4b2f3304ccba0b81fa99433..3941725c43ab516ffb1582324a2415e986340476 100644 (file)
--- a/README
+++ b/README
@@ -1247,6 +1247,20 @@ 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
index 46fae1877520796ec57869484d74785c4a78d08c..c34000a6ebe7d4d0d5fbf9fabb857c7e815a5077 100644 (file)
 #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"
index 7219b7319c5358c5d6f77d06accd5be0febbd69e..5e9f83225016056c7b79bc6fb7196f058fca7275 100644 (file)
@@ -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.
@@ -53,6 +54,120 @@ enum tpm_nv_index {
        TPM_NV_INDEX_DIR        = 0x10000001,
 };
 
+/**
+ * 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.
  *
@@ -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 */
index 42c9bea0f9421a8f0460b183da10e08707b7bbe1..f0b4f59eafc73d77e13c1d6d5ca775a081409296 100644 (file)
--- 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 */