diff --git a/common/Makefile b/common/Makefile
index fc73ec2..b9b4a51 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -2,13 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-SRCS = utility_stub.c
+SRCS = utility_stub.c tlcl_stub.c
 OBJS = $(SRCS:.c=.o)
 
 all:	libcommon.a
 
 libcommon.a:	$(OBJS)
-	ar rs $@ $<
+	ar rs $@ $^
 
 .c.o:	$(OBJS)
 	$(CC) $(CFLAGS) $(INCLUDES) -c $< -o $@
diff --git a/common/tlcl_stub.c b/common/tlcl_stub.c
new file mode 100644
index 0000000..0b4625b
--- /dev/null
+++ b/common/tlcl_stub.c
@@ -0,0 +1,28 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Stub implementations of TPM Lite Library.
+ */
+
+#include <tss/tcs.h>
+
+void TlclLibinit(void) { return; }
+void TlclStartup(void) { return; }
+void TlclSelftestfull(void) { return; }
+void TlclDefineSpace(uint32_t index, uint32_t perm, uint32_t size) { return; }
+uint32_t TlclWrite(uint32_t index, uint8_t *data, uint32_t length) {
+  return TPM_SUCCESS;
+}
+uint32_t TlclRead(uint32_t index, uint8_t *data, uint32_t length) {
+  return TPM_SUCCESS;
+}
+void TlclWriteLock(uint32_t index) { return; }
+void TlclReadLock(uint32_t index) { return; }
+void TlclAssertPhysicalPresence(void) { return; }
+void TlclSetNvLocked(void) { return; }
+int TlclIsOwned(void) { return 0; }
+void TlclForceClear(void) { return; }
+void TlclPhysicalEnable(void) { return; }
+int TlclPhysicalSetDeactivated(uint8_t flag) { return TPM_SUCCESS; }
+int TlclGetFlags(uint8_t* disable, uint8_t* deactivated) { return TPM_SUCCESS; }
diff --git a/include/firmware_image.h b/include/firmware_image.h
index 3f7bc80..611d31d 100644
--- a/include/firmware_image.h
+++ b/include/firmware_image.h
@@ -27,8 +27,8 @@
   uint16_t header_len;  /* Length of the header. */
   uint16_t firmware_sign_algorithm;  /* Signature algorithm used by the signing
                                       * key. */
-  uint8_t* firmware_sign_key;  /* Pre-processed public half of signing key. */
   uint16_t firmware_key_version;  /* Key Version# for preventing rollbacks. */
+  uint8_t* firmware_sign_key;  /* Pre-processed public half of signing key. */
   uint8_t header_checksum[SHA512_DIGEST_SIZE];  /* SHA-512 hash of the header.*/
 
   uint8_t firmware_key_signature[RSA8192NUMBYTES];  /* Signature of the header
@@ -113,7 +113,10 @@
 #define VERIFY_FIRMWARE_PREAMBLE_SIGNATURE_FAILED 4
 #define VERIFY_FIRMWARE_SIGNATURE_FAILED 5
 #define VERIFY_FIRMWARE_WRONG_MAGIC 6
-#define VERIFY_FIRMWARE_MAX 7  /* Generic catch-all. */
+#define VERIFY_FIRMWARE_WRONG_HEADER_CHECKSUM 7
+#define VERIFY_FIRMWARE_KEY_ROLLBACK 8
+#define VERIFY_FIRMWARE_VERSION_ROLLBACK 9
+#define VERIFY_FIRMWARE_MAX 10  /* Total number of error codes. */
 
 extern char* kVerifyFirmwareErrors[VERIFY_FIRMWARE_MAX];
 
@@ -198,4 +201,26 @@
  */
 int AddFirmwareSignature(FirmwareImage* image, const char* signing_key_file);
 
+/* Returns the logical version of a firmware blob which is calculated as
+ * (firmware_key_version << 16 | firmware_version). */
+uint32_t GetLogicalFirmwareVersion(uint8_t* firmware_blob);
+
+#define  BOOT_FIRMWARE_A_CONTINUE 1
+#define  BOOT_FIRMWARE_B_CONTINUE 2
+#define  BOOT_FIRMWARE_RECOVERY_CONTINUE 3
+
+/* This function is the driver used by the RO firmware to
+ * determine which copy of the firmware to boot from. It performs
+ * the requisite rollback index checking, including updating them,
+ * if required.
+ *
+ * Returns the code path to follow. It is one of:
+ * BOOT_FIRMWARE_A_CONTINUE          Boot from Firmware A
+ * BOOT_FIRMWARE_B_CONTINUE          Boot from Firmware B
+ * BOOT_FIRMWARE_RECOVERY_CONTINUE   Jump to recovery mode
+ */
+int VerifyFirmwareDriver_f(uint8_t* root_key_blob,
+                           uint8_t* firmwareA,
+                           uint8_t* firmwareB);
+
 #endif  /* VBOOT_REFERENCE_FIRMWARE_IMAGE_H_ */
diff --git a/include/rollback_index.h b/include/rollback_index.h
new file mode 100644
index 0000000..d4e47ac
--- /dev/null
+++ b/include/rollback_index.h
@@ -0,0 +1,36 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Functions for querying, manipulating and locking rollback indices
+ * stored in the TPM NVRAM.
+ */
+
+#ifndef VBOOT_REFERENCE_ROLLBACK_INDEX_H_
+#define VBOOT_REFERENCE_ROLLBACK_INDEX_H_
+
+#include <stdint.h>
+
+extern uint16_t g_firmware_key_version;
+extern uint16_t g_firmware_version;
+extern uint16_t g_kernel_key_version;
+extern uint16_t g_kernel_version;
+
+/* Rollback version types. */
+#define FIRMWARE_KEY_VERSION 0
+#define FIRMWARE_VERSION 1
+#define KERNEL_KEY_VERSION 2
+#define KERNEL_VERSION 3
+
+/* TPM NVRAM location indices. */
+#define FIRMWARE_KEY_VERSION_NV_INDEX  0x1001
+#define FIRMWARE_VERSION_NV_INDEX 0x1002
+#define KERNEL_KEY_VERSION_NV_INDEX 0x1003
+#define KERNEL_VERSION_NV_INDEX 0x1004
+
+void SetupTPM(void);
+uint16_t GetStoredVersion(int type);
+int WriteStoredVersion(int type, uint16_t version);
+void LockStoredVersion(int type);
+
+#endif  /* VBOOT_REFERENCE_ROLLBACK_INDEX_H_ */
diff --git a/include/utility.h b/include/utility.h
index 5dc6d28..7971347 100644
--- a/include/utility.h
+++ b/include/utility.h
@@ -13,6 +13,14 @@
 #include <inttypes.h>
 #include <string.h>
 
+/* Combine [msw] and [lsw] uint16s to a uint32_t with its [msw] and
+ * [lsw] forming the most and least signficant 16-bit words.
+ */
+#define CombineUint16Pair(msw,lsw) (((msw) << 16) |     \
+                                    (((lsw)) & 0xFFFF))
+/* Return the minimum of (a) or (b). */
+#define Min(a, b) (((a) < (b)) ? (a) : (b))
+
 /* Allocate [size] bytes and return a pointer to the allocated memory. Abort
  * on error.
  */
diff --git a/tests/Makefile b/tests/Makefile
index 6617a41..931e3f5 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -7,11 +7,13 @@
 INCLUDES ?= -I../include/
 TOP ?= ../
 
-FIRMWARE_LIBS = $(TOP)/crypto/libcrypto.a $(TOP)/common/libcommon.a
-LIBS = $(TOP)/utils/kernel_image.o $(TOP)/utils/firmware_image.o \
-	$(TOP)/utils/file_keys.o $(TOP)/utils/signature_digest.o -lcrypto
+BASE_LIBS = $(TOP)/crypto/libcrypto.a $(TOP)/common/libcommon.a
+IMAGE_LIBS = $(TOP)/utils/firmware_image.o $(TOP)/utils/kernel_image.o
+UTIL_LIBS = $(TOP)/utils/file_keys.o $(TOP)/utils/signature_digest.o
+LIBS = $(IMAGE_LIBS) $(UTIL_LIBS) -lcrypto $(BASE_LIBS)
 
 tests: firmware_image_tests \
+	firmware_rollback_tests \
 	firmware_verify_benchmark \
 	kernel_image_tests \
 	kernel_verify_benchmark \
@@ -22,38 +24,47 @@
 	verify_firmware_fuzz_driver \
 	verify_kernel_fuzz_driver
 
-firmware_image_tests: firmware_image_tests.c
-	$(CC) $(CFLAGS) $(INCLUDES) $< -o $@ $(LIBS) $(FIRMWARE_LIBS)
+firmware_image_tests: firmware_image_tests.c rollback_index_mock.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(LIBS)
 
-firmware_verify_benchmark: firmware_verify_benchmark.c timer_utils.c
-	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(LIBS) $(FIRMWARE_LIBS)
+firmware_rollback_tests: firmware_rollback_tests.c rollback_index_mock.c test_common.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(LIBS)
 
-kernel_image_tests: kernel_image_tests.c
-	$(CC) $(CFLAGS) $(INCLUDES) $< -o $@ $(LIBS) $(FIRMWARE_LIBS)
+firmware_verify_benchmark: firmware_verify_benchmark.c timer_utils.c \
+	rollback_index_mock.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(LIBS)
 
-kernel_verify_benchmark: kernel_verify_benchmark.c timer_utils.c
-	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(LIBS) $(FIRMWARE_LIBS)
+kernel_image_tests: kernel_image_tests.c rollback_index_mock.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(LIBS)
+
+kernel_verify_benchmark: kernel_verify_benchmark.c timer_utils.c \
+	rollback_index_mock.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(LIBS)
 
 rsa_padding_test: rsa_padding_test.c
-	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(LIBS) $(FIRMWARE_LIBS)
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(UTIL_LIBS) $(BASE_LIBS) \
+	-lcrypto
 
 rsa_verify_benchmark: rsa_verify_benchmark.c timer_utils.c
-	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(LIBS) $(FIRMWARE_LIBS)
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(UTIL_LIBS) $(BASE_LIBS) \
+	-lcrypto
 
-sha_benchmark:	sha_benchmark.c timer_utils.c $(FIRMWARE_LIBS)
-	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt
+sha_benchmark:	sha_benchmark.c timer_utils.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ -lrt $(BASE_LIBS)
 
 sha_tests: sha_tests.c
-	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(FIRMWARE_LIBS)
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(BASE_LIBS)
 
-verify_firmware_fuzz_driver: verify_firmware_fuzz_driver.c
-	$(CC) $(CFLAGS) $(INCLUDES) $< -o $@ $(LIBS) $(FIRMWARE_LIBS)
+verify_firmware_fuzz_driver: verify_firmware_fuzz_driver.c \
+	rollback_index_mock.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(LIBS)
 
-verify_kernel_fuzz_driver: verify_kernel_fuzz_driver.c
-	$(CC) $(CFLAGS) $(INCLUDES) $< -o $@ $(LIBS) $(FIRMWARE_LIBS)
+verify_kernel_fuzz_driver: verify_kernel_fuzz_driver.c rollback_index_mock.c
+	$(CC) $(CFLAGS) $(INCLUDES) $^ -o $@ $(LIBS)
 
 clean:
 	rm -f firmware_image_tests \
+		firmware_rollback_tests \
 		firmware_verify_benchmark \
 		kernel_image_tests \
 		kernel_verify_benchmark \
diff --git a/tests/firmware_image_tests.c b/tests/firmware_image_tests.c
index 3df7cb0..b252735 100644
--- a/tests/firmware_image_tests.c
+++ b/tests/firmware_image_tests.c
@@ -12,18 +12,18 @@
 #include "firmware_image.h"
 #include "rsa_utility.h"
 #include "utility.h"
+#include "rollback_index.h"
 
 /* ANSI Color coding sequences. */
 #define COL_GREEN "\e[1;32m"
-#define COL_RED "\e[0;31m]"
+#define COL_RED "\e[0;31m"
 #define COL_STOP "\e[m"
 
 int TEST_EQ(int result, int expected_result, char* testname) {
   if (result == expected_result) {
     fprintf(stderr, "%s Test " COL_GREEN " PASSED\n" COL_STOP, testname);
     return 1;
-  }
-  else {
+  } else {
     fprintf(stderr, "%s Test " COL_RED " FAILED\n" COL_STOP, testname);
     return 0;
   }
@@ -33,7 +33,9 @@
                                          uint8_t* firmware_sign_key,
                                          int firmware_key_version,
                                          int firmware_version,
-                                         int firmware_len) {
+                                         int firmware_len,
+                                         const char* root_key_file,
+                                         const char* firmware_key_file) {
   FirmwareImage* image = FirmwareImageNew();
 
   Memcpy(image->magic, FIRMWARE_MAGIC, FIRMWARE_MAGIC_SIZE);
@@ -58,6 +60,18 @@
   image->firmware_data = Malloc(image->firmware_len);
   Memset(image->firmware_data, 'F', image->firmware_len);
 
+  /* Generate and populate signatures. */
+  if (!AddFirmwareKeySignature(image, root_key_file)) {
+    fprintf(stderr, "Couldn't create key signature.\n");
+    FirmwareImageFree(image);
+    return NULL;
+  }
+
+  if (!AddFirmwareSignature(image, firmware_key_file)) {
+    fprintf(stderr, "Couldn't create firmware and preamble signature.\n");
+    FirmwareImageFree(image);
+    return NULL;
+  }
   return image;
 }
 
@@ -79,7 +93,6 @@
   return success;
 }
 
-
 /* Normal FirmwareImage Verification Tests. */
 int VerifyFirmwareImageTest(FirmwareImage* image,
                             RSAPublicKey* root_key) {
@@ -142,14 +155,17 @@
 
 int main(int argc, char* argv[]) {
   uint64_t len;
+  const char* root_key_file = NULL;
+  const char* firmware_key_file = NULL;
   uint8_t* firmware_sign_key_buf = NULL;
   uint8_t* root_key_blob = NULL;
   uint8_t* firmware_blob = NULL;
   uint64_t firmware_blob_len = 0;
   FirmwareImage* image = NULL;
-  RSAPublicKey* root_key = NULL;
+  RSAPublicKey* root_key_pub = NULL;
   int error_code = 0;
-
+  int algorithm;
+  SetupTPM();
   if(argc != 6) {
     fprintf(stderr, "Usage: %s <algorithm> <root key> <processed root pubkey>"
             " <signing key> <processed signing key>\n", argv[0]);
@@ -157,30 +173,24 @@
   }
 
   /* Read verification keys and create a test image. */
-  root_key = RSAPublicKeyFromFile(argv[3]);
+  algorithm = atoi(argv[1]);
+  root_key_pub = RSAPublicKeyFromFile(argv[3]);
   root_key_blob = BufferFromFile(argv[3], &len);
   firmware_sign_key_buf = BufferFromFile(argv[5], &len);
-  image = GenerateTestFirmwareImage(atoi(argv[1]), firmware_sign_key_buf, 1,
-                                    1, 1000);
+  root_key_file = argv[2];
+  firmware_key_file = argv[4];
+  image = GenerateTestFirmwareImage(algorithm,
+                                    firmware_sign_key_buf,
+                                    1,  /* Firmware Key Version. */
+                                    1,  /* Firmware Version. */
+                                    1000,  /* Firmware length. */
+                                    root_key_file,
+                                    firmware_key_file);
 
-  if (!root_key || !firmware_sign_key_buf || !image) {
+  if (!root_key_pub || !firmware_sign_key_buf || !image) {
     error_code = 1;
     goto failure;
   }
-
-  /* Generate and populate signatures. */
-  if (!AddFirmwareKeySignature(image, argv[2])) {
-    fprintf(stderr, "Couldn't create key signature.\n");
-    error_code = 1;
-    goto failure;
-  }
-
-  if (!AddFirmwareSignature(image, argv[4])) {
-    fprintf(stderr, "Couldn't create firmware and preamble signature.\n");
-    error_code = 1;
-    goto failure;
-  }
-
   firmware_blob = GetFirmwareBlob(image, &firmware_blob_len);
 
   /* Test Firmware blob verify operations. */
@@ -188,9 +198,9 @@
     error_code = 255;
 
   /* Test FirmwareImage verify operations. */
-  if (!VerifyFirmwareImageTest(image, root_key))
+  if (!VerifyFirmwareImageTest(image, root_key_pub))
     error_code = 255;
-  if (!VerifyFirmwareImageTamperTest(image, root_key))
+  if (!VerifyFirmwareImageTamperTest(image, root_key_pub))
     error_code = 255;
 
 failure:
@@ -198,7 +208,7 @@
   FirmwareImageFree(image);
   Free(firmware_sign_key_buf);
   Free(root_key_blob);
-  RSAPublicKeyFree(root_key);
+  RSAPublicKeyFree(root_key_pub);
 
   return error_code;
 }
diff --git a/tests/firmware_rollback_tests.c b/tests/firmware_rollback_tests.c
new file mode 100644
index 0000000..19ac850
--- /dev/null
+++ b/tests/firmware_rollback_tests.c
@@ -0,0 +1,145 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Tests for checking firmware rollback-prevention logic.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "file_keys.h"
+#include "firmware_image.h"
+#include "rsa_utility.h"
+#include "utility.h"
+#include "rollback_index.h"
+#include "test_common.h"
+
+/* Generates a test firmware image for rollback tests with a given
+ * [firmware_key_version] and [firmware_version]. If [is_corrupt] is 1,
+ * then the image has invalid signatures and will fail verification. */
+uint8_t* GenerateRollbackTestImage(int firmware_key_version,
+                                   int firmware_version,
+                                   int is_corrupt) {
+  FirmwareImage* image = NULL;
+  uint8_t* firmware_blob = NULL;
+  const char* firmare_sign_key_pub_file = "testkeys/key_rsa1024.keyb";
+  uint8_t* firmware_sign_key = NULL;
+  const char* root_key_file = "testkeys/key_rsa8192.pem";
+  const char* firmware_key_file = "testkeys/key_rsa1024.pem";
+  uint64_t len;
+  firmware_sign_key = BufferFromFile(firmare_sign_key_pub_file,
+                                     &len);
+  if (!firmware_sign_key)
+    return NULL;
+
+  image = FirmwareImageNew();
+  if (!image)
+    return NULL;
+
+  Memcpy(image->magic, FIRMWARE_MAGIC, FIRMWARE_MAGIC_SIZE);
+  image->firmware_sign_algorithm = 0;  /* RSA1024/SHA1 */
+  image->firmware_sign_key = (uint8_t*) Malloc(
+      RSAProcessedKeySize(image->firmware_sign_algorithm));
+  Memcpy(image->firmware_sign_key, firmware_sign_key,
+         RSAProcessedKeySize(image->firmware_sign_algorithm));
+  image->firmware_key_version = firmware_key_version;
+  Free(firmware_sign_key);
+
+  /* Update correct header length. */
+  image->header_len = GetFirmwareHeaderLen(image);
+
+  /* Calculate SHA-512 digest on header and populate header_checksum. */
+  CalculateFirmwareHeaderChecksum(image, image->header_checksum);
+
+  /* Populate firmware and preamble with dummy data. */
+  image->firmware_version = firmware_version;
+  image->firmware_len = 1;
+  image->preamble_signature = image->firmware_signature = NULL;
+  Memset(image->preamble, 'P', FIRMWARE_PREAMBLE_SIZE);
+  image->firmware_data = Malloc(image->firmware_len);
+  Memset(image->firmware_data, 'F', image->firmware_len);
+
+  /* Generate and populate signatures. */
+  if (!AddFirmwareKeySignature(image, root_key_file)) {
+    fprintf(stderr, "Couldn't create key signature.\n");
+    FirmwareImageFree(image);
+    return NULL;
+  }
+
+  if (!AddFirmwareSignature(image, firmware_key_file)) {
+    fprintf(stderr, "Couldn't create firmware and preamble signature.\n");
+    FirmwareImageFree(image);
+    return NULL;
+  }
+  if (is_corrupt) {
+    /* Invalidate image. */
+    Memset(image->firmware_data, 'X', image->firmware_len);
+  }
+
+  firmware_blob = GetFirmwareBlob(image, &len);
+  FirmwareImageFree(image);
+  return firmware_blob;
+}
+
+/* Tests that check for correctness of the VerifyFirmwareDriver_f() logic
+ * and rollback prevention. */
+void VerifyFirmwareDriverTest(void) {
+  uint8_t* valid_firmwareA = NULL;
+  uint8_t* valid_firmwareB = NULL;
+  uint8_t* corrupt_firmwareA = NULL;
+  uint8_t* corrupt_firmwareB = NULL;
+  uint64_t len;
+  uint8_t* root_key_pub = BufferFromFile("testkeys/key_rsa8192.keyb",
+                                         &len);
+
+  /* Initialize rollback index state. */
+  g_firmware_key_version = 1;
+  g_firmware_version = 1;
+
+  valid_firmwareA = GenerateRollbackTestImage(1, 1, 0);
+  valid_firmwareB = GenerateRollbackTestImage(1, 1, 0);
+  corrupt_firmwareA = GenerateRollbackTestImage(1, 1, 1);
+  corrupt_firmwareB = GenerateRollbackTestImage(1, 1, 1);
+
+  TEST_EQ(VerifyFirmwareDriver_f(root_key_pub,
+                                 valid_firmwareA, valid_firmwareB),
+          BOOT_FIRMWARE_A_CONTINUE,
+          "Firmware A (Valid with current version), "
+          "Firmware B (Valid with current version)");
+  TEST_EQ(VerifyFirmwareDriver_f(root_key_pub,
+                                 corrupt_firmwareA, valid_firmwareB),
+          BOOT_FIRMWARE_B_CONTINUE,
+          "Firmware A (Corrupt with current version), "
+          "FirmwareB (Valid with current version)");
+  TEST_EQ(VerifyFirmwareDriver_f(root_key_pub,
+                                 valid_firmwareA, corrupt_firmwareB),
+          BOOT_FIRMWARE_A_CONTINUE,
+          "Firmware A (Valid with current version), "
+          "FirmwareB (Corrupt with current version)");
+  TEST_EQ(VerifyFirmwareDriver_f(root_key_pub,
+                                 corrupt_firmwareA, corrupt_firmwareB),
+          BOOT_FIRMWARE_RECOVERY_CONTINUE,
+          "Firmware A (Corrupt with current version), "
+          "FirmwareB (Corrupt with current version");
+  g_firmware_key_version = 2;
+  g_firmware_version = 2;
+  TEST_EQ(VerifyFirmwareDriver_f(root_key_pub, valid_firmwareA, valid_firmwareB),
+          BOOT_FIRMWARE_RECOVERY_CONTINUE,
+          "Firmware A (Valid with old version), "
+          "Old Firmware B (Valid with old version)");
+
+  Free(root_key_pub);
+  Free(valid_firmwareA);
+  Free(valid_firmwareB);
+  Free(corrupt_firmwareA);
+  Free(corrupt_firmwareB);
+}
+
+int main(int argc, char* argv[]) {
+  int error_code = 0;
+  VerifyFirmwareDriverTest();
+  if (!gTestSuccess)
+    error_code = 255;
+  return error_code;
+}
diff --git a/tests/rollback_index_mock.c b/tests/rollback_index_mock.c
new file mode 100644
index 0000000..047fb8a
--- /dev/null
+++ b/tests/rollback_index_mock.c
@@ -0,0 +1,61 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Mock rollback index library for testing.
+ */
+
+#include "rollback_index.h"
+
+#include <stdio.h>
+#include <stdint.h>
+
+uint16_t g_firmware_key_version = 0;
+uint16_t g_firmware_version = 0;
+uint16_t g_kernel_key_version = 0;
+uint16_t g_kernel_version = 0;
+
+void SetupTPM(void) {
+  fprintf(stderr, "Rollback Index Library Mock: TPM initialized.\n");
+}
+
+uint16_t GetStoredVersion(int type) {
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      return g_firmware_key_version;
+      break;
+    case FIRMWARE_VERSION:
+      return g_firmware_version;
+      break;
+    case KERNEL_KEY_VERSION:
+      return g_kernel_key_version;
+      break;
+    case KERNEL_VERSION:
+      return g_kernel_version;
+      break;
+  }
+  return 0;
+}
+
+int WriteStoredVersion(int type, uint16_t version) {
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      g_firmware_key_version = version;
+      break;
+    case FIRMWARE_VERSION:
+      g_firmware_version = version;
+      break;
+    case KERNEL_KEY_VERSION:
+      g_kernel_key_version = version;
+      break;
+    case KERNEL_VERSION:
+      g_kernel_version = version;
+      break;
+  }
+  fprintf(stderr, "Rollback Index Library Mock: Stored Version written.\n");
+  return 1;
+}
+
+void LockStoredVersion(int type) {
+  fprintf(stderr, "Rollback Index Library Mock: Version Locked.\n");
+}
diff --git a/tests/test_common.c b/tests/test_common.c
new file mode 100644
index 0000000..4a92f7d
--- /dev/null
+++ b/tests/test_common.c
@@ -0,0 +1,30 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Common functions used by tests.
+ */
+
+#include "test_common.h"
+
+#include <stdio.h>
+
+/* ANSI Color coding sequences. */
+#define COL_GREEN "\e[1;32m"
+#define COL_RED "\e[0;31m]"
+#define COL_STOP "\e[m"
+
+/* Global test success flag. */
+int gTestSuccess = 1;
+
+int TEST_EQ(int result, int expected_result, char* testname) {
+  if (result == expected_result) {
+    fprintf(stderr, "%s Test " COL_GREEN " PASSED\n" COL_STOP, testname);
+    return 1;
+  }
+  else {
+    fprintf(stderr, "%s Test " COL_RED " FAILED\n" COL_STOP, testname);
+    gTestSuccess = 0;
+    return 0;
+  }
+}
diff --git a/tests/test_common.h b/tests/test_common.h
new file mode 100644
index 0000000..9fa3eec
--- /dev/null
+++ b/tests/test_common.h
@@ -0,0 +1,13 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ */
+
+#ifndef VBOOT_REFERENCE_TEST_COMMON_H_
+#define VBOOT_REFERENCE_TEST_COMMON_H_
+
+int TEST_EQ(int result, int expected_result, char* testname);
+extern int gTestSuccess;
+
+#endif  /* VBOOT_REFERENCE_TEST_COMMON_H_ */
diff --git a/utils/Makefile b/utils/Makefile
index 6d5546e..597638e 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -8,12 +8,15 @@
 INCLUDES ?= -I../include/
 TOP ?= ../
 
-LIBS =  firmware_image.o kernel_image.o signature_digest.o file_keys.o
+LIBS =  firmware_image.o kernel_image.o signature_digest.o file_keys.o \
+	rollback_index.o
+
 FIRMWARELIBS = $(TOP)/crypto/libcrypto.a $(TOP)/common/libcommon.a
 
 all: dumpRSAPublicKey verify_data file_keys.o signature_digest.o \
 	firmware_image.o kernel_image.o signature_digest.o \
-	signature_digest_utility firmware_utility kernel_utility
+	signature_digest_utility firmware_utility kernel_utility \
+	rollback_index.o
 
 dumpRSAPublicKey: dumpRSAPublicKey.c
 	$(CC) $(CFLAGS) $< -o $@ -lcrypto
@@ -26,16 +29,15 @@
 
 firmware_utility: firmware_utility.cc $(LIBS) $(FIRMWARELIBS)
 	$(CXX) $(CFLAGS) $(INCLUDES) -ggdb -D__STDC_LIMIT_MACROS $< \
-	-o $@ $(FIRMWARELIBS) $(LIBS) -lcrypto
+	-o $@ $(FIRMWARELIBS) $(LIBS) $(TOP)/common/libcommon.a \
+	-lcrypto
 
 kernel_utility: kernel_utility.cc $(LIBS) $(FIRMWARELIBS)
 	$(CXX) $(CFLAGS) $(INCLUDES) -ggdb -D__STDC_LIMIT_MACROS $< \
-	-o $@ $(FIRMWARELIBS) $(LIBS) -lcrypto
+	-o $@ $(FIRMWARELIBS) $(LIBS) $(TOP)/common/libcommon.a \
+	-lcrypto
 
-signature_digest.o: signature_digest.c
-	$(CC) $(CFLAGS) $(INCLUDES) -c $< -o $@
-
-file_keys.o: file_keys.c
+.c.o:
 	$(CC) $(CFLAGS) $(INCLUDES) -c $< -o $@
 
 firmware_image.o: firmware_image.c
diff --git a/utils/firmware_image.c b/utils/firmware_image.c
index ab41fec..4098bb2 100644
--- a/utils/firmware_image.c
+++ b/utils/firmware_image.c
@@ -16,6 +16,7 @@
 
 #include "file_keys.h"
 #include "padding.h"
+#include "rollback_index.h"
 #include "rsa_utility.h"
 #include "sha_utility.h"
 #include "signature_digest.h"
@@ -97,10 +98,10 @@
   }
 
   /* Read pre-processed public half of the sign key. */
-  image->firmware_sign_key = (uint8_t*) Malloc(firmware_sign_key_len);
-  StatefulMemcpy(&st, image->firmware_sign_key, firmware_sign_key_len);
   StatefulMemcpy(&st, &image->firmware_key_version,
                  FIELD_LEN(firmware_key_version));
+  image->firmware_sign_key = (uint8_t*) Malloc(firmware_sign_key_len);
+  StatefulMemcpy(&st, image->firmware_sign_key, firmware_sign_key_len);
   StatefulMemcpy(&st, image->header_checksum, FIELD_LEN(header_checksum));
 
   /* Check whether the header checksum matches. */
@@ -155,10 +156,10 @@
                sizeof(image->header_len));
   DigestUpdate(&ctx, (uint8_t*) &image->firmware_sign_algorithm,
                sizeof(image->firmware_sign_algorithm));
-  DigestUpdate(&ctx, image->firmware_sign_key,
-               RSAProcessedKeySize(image->firmware_sign_algorithm));
   DigestUpdate(&ctx, (uint8_t*) &image->firmware_key_version,
                sizeof(image->firmware_key_version));
+  DigestUpdate(&ctx, image->firmware_sign_key,
+               RSAProcessedKeySize(image->firmware_sign_algorithm));
   checksum = DigestFinal(&ctx);
   Memcpy(header_checksum, checksum, FIELD_LEN(header_checksum));
   Free(checksum);
@@ -176,10 +177,10 @@
 
   StatefulMemcpy_r(&st, &image->header_len, FIELD_LEN(header_len));
   StatefulMemcpy_r(&st, &image->firmware_sign_algorithm, FIELD_LEN(header_len));
-  StatefulMemcpy_r(&st, image->firmware_sign_key,
-                 RSAProcessedKeySize(image->firmware_sign_algorithm));
   StatefulMemcpy_r(&st, &image->firmware_key_version,
                  FIELD_LEN(firmware_key_version));
+  StatefulMemcpy_r(&st, image->firmware_sign_key,
+                 RSAProcessedKeySize(image->firmware_sign_algorithm));
   StatefulMemcpy_r(&st, &image->header_checksum, FIELD_LEN(header_checksum));
 
   if (st.remaining_len != 0) {  /* Underrun or Overrun. */
@@ -314,6 +315,9 @@
   "Preamble Signature Failed.",
   "Firmware Signature Failed.",
   "Wrong Firmware Magic.",
+  "Invalid Firmware Header Checksum.",
+  "Firmware Signing Key Rollback.",
+  "Firmware Version Rollback."
 };
 
 int VerifyFirmwareHeader(const uint8_t* root_key_blob,
@@ -343,7 +347,7 @@
   *algorithm = (int) algo;
   firmware_sign_key_len = RSAProcessedKeySize(*algorithm);
 
-  /* Verify if header len is correct? */
+  /* Verify that header len is correct. */
   if (hlen != (base_header_checksum_offset +
                firmware_sign_key_len +
                FIELD_LEN(header_checksum)))
@@ -360,19 +364,18 @@
                                  firmware_sign_key_len),
                   FIELD_LEN(header_checksum))) {
     Free(header_checksum);
-    return VERIFY_FIRMWARE_INVALID_IMAGE;
+    return VERIFY_FIRMWARE_WRONG_HEADER_CHECKSUM;
   }
   Free(header_checksum);
 
-  /* Verify root key signature unless we are in dev mode. */
-  if (!dev_mode) {
-    if (!RSAVerifyBinary_f(root_key_blob, NULL,  /* Key to use */
-                           header_blob,  /* Data to verify */
-                           *header_len, /* Length of data */
-                           header_blob + *header_len,  /* Expected Signature */
-                           ROOT_SIGNATURE_ALGORITHM))
-      return VERIFY_FIRMWARE_ROOT_SIGNATURE_FAILED;
-  }
+  /* Root key signature on the firmware signing key is always checked
+   * irrespective of dev mode. */
+  if (!RSAVerifyBinary_f(root_key_blob, NULL,  /* Key to use */
+                         header_blob,  /* Data to verify */
+                         *header_len, /* Length of data */
+                         header_blob + *header_len,  /* Expected Signature */
+                         ROOT_SIGNATURE_ALGORITHM))
+    return VERIFY_FIRMWARE_ROOT_SIGNATURE_FAILED;
   return 0;
 }
 
@@ -382,6 +385,10 @@
                            int* firmware_len) {
   uint32_t len;
   int preamble_len;
+  uint16_t firmware_version;
+
+  Memcpy(&firmware_version, preamble_blob, sizeof(firmware_version));
+
   preamble_len = (FIELD_LEN(firmware_version) +
                   FIELD_LEN(firmware_len) +
                   FIELD_LEN(preamble));
@@ -442,7 +449,8 @@
    * times. */
   firmware_sign_key_len = RSAProcessedKeySize(algorithm);
   firmware_sign_key_ptr = header_ptr + (FIELD_LEN(header_len) +
-                               FIELD_LEN(firmware_sign_algorithm));
+                                        FIELD_LEN(firmware_sign_algorithm) +
+                                        FIELD_LEN(firmware_key_version));
   firmware_sign_key = RSAPublicKeyFromBuf(firmware_sign_key_ptr,
                                           firmware_sign_key_len);
   signature_len = siglen_map[algorithm];
@@ -458,7 +466,7 @@
   }
   /* Only continue if firmware data verification succeeds. */
   firmware_ptr = (preamble_ptr +
-                  GetFirmwarePreambleLen(NULL) + 
+                  GetFirmwarePreambleLen(NULL) +
                   signature_len);
 
   if ((error_code = VerifyFirmwareData(firmware_sign_key, firmware_ptr,
@@ -494,16 +502,21 @@
    *  1) verifying the header length is correct.
    *  2) header_checksum is correct.
    */
+  /* TODO(gauravsh): The [dev_mode] switch is actually irrelevant
+   * for the firmware verification.
+   * Change this to always verify the root key signature and change
+   * test expectations appropriately.
+   */
   if (!dev_mode) {
     DigestInit(&ctx, ROOT_SIGNATURE_ALGORITHM);
     DigestUpdate(&ctx, (uint8_t*) &image->header_len,
                  FIELD_LEN(header_len));
     DigestUpdate(&ctx, (uint8_t*) &image->firmware_sign_algorithm,
                  FIELD_LEN(firmware_sign_algorithm));
-    DigestUpdate(&ctx, image->firmware_sign_key,
-                 RSAProcessedKeySize(image->firmware_sign_algorithm));
     DigestUpdate(&ctx, (uint8_t*) &image->firmware_key_version,
                  FIELD_LEN(firmware_key_version));
+    DigestUpdate(&ctx, image->firmware_sign_key,
+                 RSAProcessedKeySize(image->firmware_sign_algorithm));
     DigestUpdate(&ctx, image->header_checksum,
                  FIELD_LEN(header_checksum));
     header_digest = DigestFinal(&ctx);
@@ -613,3 +626,117 @@
   Free(firmware_signature);
   return 1;
 }
+
+uint32_t GetLogicalFirmwareVersion(uint8_t* firmware_blob) {
+  uint16_t firmware_key_version;
+  uint16_t firmware_version;
+  uint16_t firmware_sign_algorithm;
+  int firmware_sign_key_len;
+  Memcpy(&firmware_sign_algorithm,
+         firmware_blob + (FIELD_LEN(magic) +  /* Offset to field. */
+                          FIELD_LEN(header_len)),
+         sizeof(firmware_sign_algorithm));
+  Memcpy(&firmware_key_version,
+         firmware_blob + (FIELD_LEN(magic) +  /* Offset to field. */
+                          FIELD_LEN(header_len) +
+                          FIELD_LEN(firmware_sign_algorithm)),
+         sizeof(firmware_key_version));
+  if (firmware_sign_algorithm >= kNumAlgorithms)
+    return 0;
+  firmware_sign_key_len = RSAProcessedKeySize(firmware_sign_algorithm);
+  Memcpy(&firmware_version,
+         firmware_blob +  (FIELD_LEN(magic) +  /* Offset to field. */
+                           FIELD_LEN(header_len) +
+                           FIELD_LEN(firmware_key_version) +
+                           firmware_sign_key_len +
+                           FIELD_LEN(header_checksum) +
+                           FIELD_LEN(firmware_key_signature)),
+         sizeof(firmware_version));
+  return CombineUint16Pair(firmware_key_version, firmware_version);
+}
+
+int VerifyFirmwareDriver_f(uint8_t* root_key_blob,
+                           uint8_t* firmwareA,
+                           uint8_t* firmwareB) {
+  /* Contains the logical firmware version (32-bit) which is calculated as
+   * (firmware_key_version << 16 | firmware_version) where
+   * [firmware_key_version] [firmware_version] are both 16-bit.
+   */
+  uint32_t firmwareA_lversion, firmwareB_lversion;
+  uint8_t firmwareA_is_verified = 0;  /* Whether firmwareA verify succeeded. */
+  uint32_t min_lversion;  /* Minimum of firmware A and firmware lversion. */
+  uint32_t stored_lversion;  /* Stored logical version in the TPM. */
+
+  /* Initialize the TPM since we'll be reading the rollback indices. */
+  SetupTPM();
+
+  /* We get the key versions by reading directly from the image blobs without
+   * any additional (expensive) sanity checking on the blob since it's faster to
+   * outright reject a firmware with an older firmware key version. A malformed
+   * or corrupted firmware blob will still fail when VerifyFirmware() is called
+   * on it.
+   */
+  firmwareA_lversion = GetLogicalFirmwareVersion(firmwareA);
+  firmwareB_lversion = GetLogicalFirmwareVersion(firmwareB);
+  min_lversion  = Min(firmwareA_lversion, firmwareB_lversion);
+  stored_lversion = CombineUint16Pair(GetStoredVersion(FIRMWARE_KEY_VERSION),
+                                      GetStoredVersion(FIRMWARE_VERSION));
+  /* Always try FirmwareA first. */
+  if (VERIFY_FIRMWARE_SUCCESS == VerifyFirmware(root_key_blob, firmwareA,
+                                                0))
+    firmwareA_is_verified = 1;
+  if (firmwareA_is_verified && (stored_lversion < firmwareA_lversion)) {
+    /* Stored version may need to be updated but only if FirmwareB
+     * is successfully verified and has a logical version greater than
+     * the stored logical version. */
+    if (VERIFY_FIRMWARE_SUCCESS == VerifyFirmware(root_key_blob, firmwareB,
+                                                    0)) {
+        if (stored_lversion < firmwareB_lversion) {
+          WriteStoredVersion(FIRMWARE_KEY_VERSION,
+                             (uint16_t) (min_lversion >> 16));
+          WriteStoredVersion(FIRMWARE_VERSION,
+                             (uint16_t) (min_lversion & 0x00FFFF));
+          stored_lversion = min_lversion;  /* Update stored version as it's used
+                                            * later. */
+        }
+    }
+  }
+  /* Lock Firmware TPM rollback indices from further writes. */
+  /* TODO(gauravsh): Figure out if these can be combined into one
+   * 32-bit location since we seem to always use them together. This can help
+   * us minimize the number of NVRAM writes/locks (which are limited over flash
+   * memory lifetimes.
+   */
+  LockStoredVersion(FIRMWARE_KEY_VERSION);
+  LockStoredVersion(FIRMWARE_VERSION);
+
+  /* Determine which firmware (if any) to jump to.
+   *
+   * We always attempt to jump to FirmwareA first. If verification of FirmwareA
+   * fails, we try FirmwareB. In all cases, if the firmware successfully
+   * verified but is a rollback, we jump to recovery.
+   *
+   * Note: This means that if FirmwareA verified successfully and is a
+   * rollback, then no attempt is made to check FirmwareB. We still jump to
+   * recovery. FirmwareB is only used as a backup in case FirmwareA gets
+   * corrupted. Since newer firmware updates are always written to A,
+   * the case where firmware A is verified but a rollback should not occur in
+   * normal operation.
+   */
+  if (firmwareA_is_verified) {
+    if (stored_lversion <= firmwareA_lversion)
+      return BOOT_FIRMWARE_A_CONTINUE;
+  } else {
+    /* If FirmwareA was not valid, then we skipped over the
+     * check to update the rollback indices and a Verify of FirmwareB wasn't
+     * attempted.
+     * If FirmwareB is not a rollback, then we attempt to do the verification.
+     */
+    if (stored_lversion <= firmwareB_lversion &&
+        (VERIFY_FIRMWARE_SUCCESS == VerifyFirmware(root_key_blob, firmwareB,
+                                                   0)))
+      return BOOT_FIRMWARE_B_CONTINUE;
+  }
+  /* D'oh: No bootable firmware. */
+  return BOOT_FIRMWARE_RECOVERY_CONTINUE;
+}
diff --git a/utils/rollback_index.c b/utils/rollback_index.c
new file mode 100644
index 0000000..0b65bf4
--- /dev/null
+++ b/utils/rollback_index.c
@@ -0,0 +1,148 @@
+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Functions for querying, manipulating and locking rollback indices
+ * stored in the TPM NVRAM.
+ */
+
+#include "rollback_index.h"
+
+#include <stdint.h>
+#include <tss/tcs.h>
+
+#include "tlcl.h"
+
+uint16_t g_firmware_key_version = 0;
+uint16_t g_firmware_version = 0;
+uint16_t g_kernel_key_version = 0;
+uint16_t g_kernel_version = 0;
+
+static void InitializeSpaces(void) {
+  uint16_t zero = 0;
+  uint32_t perm = TPM_NV_PER_WRITE_STCLEAR | TPM_NV_PER_PPWRITE;
+
+  printf("Initializing spaces\n");
+  TlclSetNvLocked();  /* useful only the first time */
+
+  TlclDefineSpace(FIRMWARE_KEY_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(FIRMWARE_KEY_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+
+  TlclDefineSpace(FIRMWARE_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(FIRMWARE_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+
+  TlclDefineSpace(KERNEL_KEY_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(KERNEL_KEY_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+
+  TlclDefineSpace(KERNEL_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(KERNEL_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+}
+
+static void EnterRecovery(void) {
+  /* Temporary recovery stub. Currently just initalizes spaces. */
+  InitializeSpaces();
+}
+
+static int GetTPMRollbackIndices(void) {
+  /* We just perform the reads, making sure they succeed. A failure means that
+   * the rollback index locations are some how messed up and we must jump to
+   * recovery */
+  if (TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                              (uint8_t*) &g_firmware_key_version,
+                              sizeof(g_firmware_key_version)) ||
+      TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                              (uint8_t*) &g_firmware_key_version,
+                              sizeof(g_firmware_key_version)) ||
+      TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                               (uint8_t*) &g_firmware_key_version,
+                               sizeof(g_firmware_key_version))  ||
+      TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                              (uint8_t*) &g_firmware_key_version,
+                              sizeof(g_firmware_key_version)))
+    return 0;
+  return 1;
+}
+
+
+void SetupTPM(void) {
+  TlclLibinit();
+  TlclStartup();
+  /* TODO(gauravsh): The call to self test  should probably be deferred.
+   * As per semenzato@chromium.org -
+   * TlclStartup should be called before the firmware initializes the memory
+   * controller, so the selftest can run in parallel with that. Here we should
+   * just call TlclSelftestFull to make sure the self test has
+   * completed---unless we want to rely on the NVRAM operations being available
+   * before the selftest completes. */
+  TlclSelftestfull();
+  TlclAssertPhysicalPresence();
+  if (!GetTPMRollbackIndices()) {
+    fprintf(stderr, "Ho Ho Ho! We must jump to recovery.");
+    EnterRecovery();
+  }
+}
+
+
+uint16_t GetStoredVersion(int type) {
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      return g_firmware_key_version;
+      break;
+    case FIRMWARE_VERSION:
+      return g_firmware_version;
+      break;
+    case KERNEL_KEY_VERSION:
+      return g_kernel_key_version;
+      break;
+    case KERNEL_VERSION:
+      return g_kernel_version;
+      break;
+  }
+  return 0;
+}
+
+int WriteStoredVersion(int type, uint16_t version) {
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      return (TPM_SUCCESS == TlclWrite(FIRMWARE_KEY_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+    case FIRMWARE_VERSION:
+      return (TPM_SUCCESS == TlclWrite(FIRMWARE_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+    case KERNEL_KEY_VERSION:
+      return (TPM_SUCCESS == TlclWrite(KERNEL_KEY_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+    case KERNEL_VERSION:
+      return (TPM_SUCCESS == TlclWrite(KERNEL_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+  }
+  return 0;
+}
+
+void LockStoredVersion(int type) {
+  /* TODO(gauravsh): Add error checking here to make sure TlclWriteLock
+   * did not fail. We must jump to recovery in that case.
+   */
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      TlclWriteLock(FIRMWARE_KEY_VERSION_NV_INDEX);
+      break;
+    case FIRMWARE_VERSION:
+      TlclWriteLock(FIRMWARE_VERSION_NV_INDEX);
+      break;
+    case KERNEL_KEY_VERSION:
+      TlclWriteLock(KERNEL_KEY_VERSION_NV_INDEX);
+      break;
+    case KERNEL_VERSION:
+      TlclWriteLock(KERNEL_VERSION_NV_INDEX);
+      break;
+  }
+}