diff --git a/docs/WidevineModularDRMSecurityIntegrationGuideforCENC_v15.pdf b/docs/WidevineModularDRMSecurityIntegrationGuideforCENC_v15.pdf
index b611c7e..248663f 100644
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diff --git a/docs/WidevineSecurityIntegrationGuideforCENCAndroidSupplement_v14.pdf b/docs/WidevineSecurityIntegrationGuideforCENCAndroidSupplement_v14.pdf
deleted file mode 100644
index ab217b5..0000000
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diff --git a/docs/WidevineSecurityIntegrationGuideforCENCAndroidSupplement_v15.pdf b/docs/WidevineSecurityIntegrationGuideforCENCAndroidSupplement_v15.pdf
new file mode 100644
index 0000000..0ce9aa6
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diff --git a/docs/Widevine_Modular_DRM_Version_15_Delta.pdf b/docs/Widevine_Modular_DRM_Version_15_Delta.pdf
index 038ad2c..fe668bf 100644
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diff --git a/docs/Widevine_OEMCrypto_Version_Compatibility.pdf b/docs/Widevine_OEMCrypto_Version_Compatibility.pdf
index 17a3a2b..301fb66 100644
Binary files a/docs/Widevine_OEMCrypto_Version_Compatibility.pdf and b/docs/Widevine_OEMCrypto_Version_Compatibility.pdf differ
diff --git a/oem_certificate_generator/oem_certificate_test_helper.py b/oem_certificate_generator/oem_certificate_test_helper.py
new file mode 100644
index 0000000..eccb125
--- /dev/null
+++ b/oem_certificate_generator/oem_certificate_test_helper.py
@@ -0,0 +1,158 @@
+# Copyright 2017 Google LLC. All Rights Reserved.
+
+"""Common test utility functions for OEM certificate generation."""
+
+import datetime
+import StringIO
+
+from cryptography import x509
+from cryptography.hazmat import backends
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.x509 import oid
+
+import oem_certificate
+
+_COUNTRY_NAME = 'US'
+_STATE_OR_PROVINCE_NAME = 'WA'
+_LOCALITY_NAME = 'Kirkland'
+_ORGANIZATION_NAME = 'CompanyXYZ'
+_ORGANIZATIONAL_UNIT_NAME = 'ContentProtection'
+
+
+_NOT_VALID_BEFORE = datetime.datetime(2001, 8, 9)
+_VALID_DURATION = 100
+_LEAF_CERT_VALID_DURATION = 8000
+_SYSTEM_ID = 2001
+_ROOT_PRIVATE_KEY_PASSPHRASE = 'root_passphrase'
+
+
+class ArgParseObject(object):
+  """A convenient object to allow adding arbitrary attribute to it."""
+
+
+def create_root_certificate_and_key():
+  """Creates a root certificate and key."""
+  key = rsa.generate_private_key(
+      public_exponent=65537,
+      key_size=3072,
+      backend=backends.default_backend())
+  subject_name = x509.Name(
+      [x509.NameAttribute(oid.NameOID.COMMON_NAME, u'root_cert')])
+  certificate = oem_certificate.build_certificate(
+      subject_name, subject_name, None,
+      datetime.datetime(2001, 8, 9), 1000, key.public_key(), key, True)
+  return (key, certificate)
+
+
+def setup_csr_args(country_name=_COUNTRY_NAME,
+                   state_or_province_name=_STATE_OR_PROVINCE_NAME,
+                   locality_name=_LOCALITY_NAME,
+                   organization_name=_ORGANIZATION_NAME,
+                   organizational_unit_name=_ORGANIZATIONAL_UNIT_NAME,
+                   key_size=4096,
+                   output_csr_file=None,
+                   output_private_key_file=None,
+                   passphrase=None,
+                   common_name=None):
+  """Sets up arguments to OEM Certificate generator for generating csr."""
+  args = ArgParseObject()
+  args.key_size = key_size
+  args.country_name = country_name
+  args.state_or_province_name = state_or_province_name
+  args.locality_name = locality_name
+  args.organization_name = organization_name
+  args.organizational_unit_name = organizational_unit_name
+  args.common_name = common_name
+  if output_csr_file:
+    args.output_csr_file = output_csr_file
+  else:
+    args.output_csr_file = StringIO.StringIO()
+  if output_private_key_file:
+    args.output_private_key_file = output_private_key_file
+  else:
+    args.output_private_key_file = StringIO.StringIO()
+  args.passphrase = passphrase
+  return args
+
+
+def setup_intermediate_cert_args(
+    csr_bytes, root_key, root_certificate, not_valid_before=_NOT_VALID_BEFORE,
+    valid_duration=_VALID_DURATION, system_id=_SYSTEM_ID,
+    root_private_key_passphrase=_ROOT_PRIVATE_KEY_PASSPHRASE,
+    output_certificate_file=None):
+  """Sets up args to OEM Cert generator for generating intermediate cert."""
+  args = ArgParseObject()
+  args.not_valid_before = not_valid_before
+  args.valid_duration = valid_duration
+  args.system_id = system_id
+  args.csr_file = StringIO.StringIO(csr_bytes)
+  args.root_private_key_passphrase = root_private_key_passphrase
+  if output_certificate_file:
+    args.output_certificate_file = output_certificate_file
+  else:
+    args.output_certificate_file = StringIO.StringIO()
+
+  serialized_private_key = root_key.private_bytes(
+      serialization.Encoding.DER,
+      format=serialization.PrivateFormat.PKCS8,
+      encryption_algorithm=serialization.BestAvailableEncryption(
+          args.root_private_key_passphrase))
+  serialized_certificate = root_certificate.public_bytes(
+      serialization.Encoding.DER)
+  args.root_certificate_file = StringIO.StringIO(serialized_certificate)
+  args.root_private_key_file = StringIO.StringIO(serialized_private_key)
+  return args
+
+
+def setup_leaf_cert_args(intermediate_key_bytes,
+                         intermediate_certificate_bytes,
+                         key_size=1024,
+                         passphrase=None,
+                         not_valid_before=_NOT_VALID_BEFORE,
+                         valid_duration=_LEAF_CERT_VALID_DURATION,
+                         output_certificate_file=None,
+                         output_private_key_file=None):
+  """Sets up args to OEM Certificate generator for generating leaf cert."""
+  args = ArgParseObject()
+  args.key_size = key_size
+  args.not_valid_before = not_valid_before
+  args.valid_duration = valid_duration
+  args.intermediate_private_key_passphrase = None
+  if output_certificate_file:
+    args.output_certificate_file = output_certificate_file
+  else:
+    args.output_certificate_file = StringIO.StringIO()
+  if output_private_key_file:
+    args.output_private_key_file = output_private_key_file
+  else:
+    args.output_private_key_file = StringIO.StringIO()
+  args.passphrase = passphrase
+
+  args.intermediate_private_key_file = StringIO.StringIO(
+      intermediate_key_bytes)
+  args.intermediate_certificate_file = StringIO.StringIO(
+      intermediate_certificate_bytes)
+  return args
+
+
+def create_intermediate_certificate_and_key_bytes(key_size=4096,
+                                                  passphrase=None,
+                                                  pem_format=True):
+  """Creates an intermediate certificate and key."""
+  csr_args = setup_csr_args(key_size=key_size, passphrase=passphrase)
+  oem_certificate.generate_csr(csr_args)
+  csr_bytes = csr_args.output_csr_file.getvalue()
+
+  root_key, root_certificate = create_root_certificate_and_key()
+  args = setup_intermediate_cert_args(csr_bytes, root_key, root_certificate)
+
+  oem_certificate.generate_intermediate_certificate(args)
+
+  cert_bytes = args.output_certificate_file.getvalue()
+  if pem_format:
+    cert = x509.load_der_x509_certificate(cert_bytes,
+                                          backends.default_backend())
+    cert_bytes = cert.public_bytes(serialization.Encoding.PEM)
+
+  return (csr_args.output_private_key_file.getvalue(), cert_bytes)
diff --git a/oemcrypto/include/OEMCryptoCENC.h b/oemcrypto/include/OEMCryptoCENC.h
index f7a560c..fffb93a 100644
--- a/oemcrypto/include/OEMCryptoCENC.h
+++ b/oemcrypto/include/OEMCryptoCENC.h
@@ -8,7 +8,7 @@
  * Reference APIs needed to support Widevine's crypto algorithms.
  *
  * See the document "WV Modular DRM Security Integration Guide for Common
- * Encryption (CENC) -- version 15" for a description of this API. You
+ * Encryption (CENC) -- version 15.2" for a description of this API. You
  * can find this document in the widevine repository as
  * docs/WidevineModularDRMSecurityIntegrationGuideforCENC_v15.pdf
  * Changes between different versions of this API are documented in the files
@@ -339,9 +339,9 @@ typedef enum OEMCrypto_Clock_Security_Level {
 
 typedef uint8_t RSA_Padding_Scheme;
 // RSASSA-PSS with SHA1.
-const RSA_Padding_Scheme kSign_RSASSA_PSS = 0x1;
+#define kSign_RSASSA_PSS ((RSA_Padding_Scheme)0x1)
 // PKCS1 with block type 1 padding (only).
-const RSA_Padding_Scheme kSign_PKCS1_Block1 = 0x2;
+#define kSign_PKCS1_Block1 ((RSA_Padding_Scheme)0x2)
 
 /*
  * OEMCrypto_HDCP_Capability is used in the key control block to enforce HDCP
@@ -376,9 +376,9 @@ typedef enum OEMCrypto_ProvisioningMethod {
 /*
  * Flags indicating full decrypt path hash supported.
  */
-const uint32_t OEMCrypto_Hash_Not_Supported = 0;
-const uint32_t OEMCrypto_CRC_Clear_Buffer = 1;
-const uint32_t OEMCrypto_Partner_Defined_Hash = 2;
+#define OEMCrypto_Hash_Not_Supported 0
+#define OEMCrypto_CRC_Clear_Buffer 1
+#define OEMCrypto_Partner_Defined_Hash 2
 
 /*
  * Return values from OEMCrypto_GetAnalogOutputFlags.
@@ -800,13 +800,17 @@ OEMCryptoResult OEMCrypto_DeriveKeysFromSessionKey(
  *   before requesting more nonces, then OEMCrypto will reset the error
  *   condition and generate valid nonces again.
  *
+ *   To prevent Birthday Paradox attacks, OEMCrypto shall verify that the value
+ *   generated is not in this session's nonce table, and that it is not in the
+ *   nonce table of any other session.
+ *
  * Parameters:
  *   [in] session: handle for the session to be used.
  *   [out] nonce: pointer to memory to receive the computed nonce.
  *
  * Results:
- *   nonce: the nonce is also stored in secure memory. At least 4 nonces should
- *   be stored for each session.
+ *   nonce: the nonce is also stored in secure memory. Each session should
+ *   store 4 nonces.
  *
  * Returns:
  *   OEMCrypto_SUCCESS success
@@ -817,11 +821,9 @@ OEMCryptoResult OEMCrypto_DeriveKeysFromSessionKey(
  *   OEMCrypto_ERROR_SYSTEM_INVALIDATED
  *
  * Threading:
- *   This is a "Session Function" and may be called simultaneously with session
- *   functions for other sessions but not simultaneously with other functions
- *   for this session. It will not be called simultaneously with initialization
- *   or usage table functions. It is as if the CDM holds a write lock for this
- *   session, and a read lock on the OEMCrypto system.
+ *   This is a "Session Initialization Function" and will not be called
+ *   simultaneously with any other function, as if the CDM holds a write lock
+ *   on the OEMCrypto system.
  *
  * Version:
  *   This method changed in API version 5.
@@ -1049,6 +1051,9 @@ OEMCryptoResult OEMCrypto_LoadSRM(const uint8_t* buffer, size_t buffer_length);
  *        entry is marked as "inactive" (either kInactiveUsed or
  *        kInactiveUnused), then the keys are not loaded, and the error
  *        OEMCrypto_ERROR_LICENSE_INACTIVE is returned.
+ *     12. The data in enc_mac_keys_iv is not identical to the 16 bytes before
+ *        enc_mac_keys.  If it is, return OEMCrypto_ERROR_INVALID_CONTEXT.
+ *
  *   Usage Table and Provider Session Token (pst)
  *
  *   If a key control block has a nonzero value for Replay_Control, then all
@@ -1627,8 +1632,8 @@ OEMCryptoResult OEMCrypto_SelectKey(OEMCrypto_SESSION session,
  *     6. If the current session has an entry in the Usage Table, and the
  *        status of that entry is either kInactiveUsed or kInactiveUnused, then
  *        return the error OEMCrypto_ERROR_LICENSE_INACTIVE.
- *     7. If an Decrypt Hash has been initialized via OEMCrypto_SetDecryptHash,
- *        and the current key's control block  does not have the
+ *     7. If a Decrypt Hash has been initialized via OEMCrypto_SetDecryptHash,
+ *        and the current key's control block does not have the
  *        Allow_Hash_Verification bit set, then do not compute a hash and
  *        return OEMCrypto_ERROR_UNKNOWN_FAILURE.
  *   If the flag is_encrypted is false, then no verification is performed. This
@@ -2201,7 +2206,7 @@ OEMCryptoResult OEMCrypto_InstallKeyboxOrOEMCert(const uint8_t* rot,
  * Version:
  *   This method is new API version 12.
  */
-OEMCrypto_ProvisioningMethod OEMCrypto_GetProvisioningMethod();
+OEMCrypto_ProvisioningMethod OEMCrypto_GetProvisioningMethod(void);
 
 /*
  * OEMCrypto_IsKeyboxOrOEMCertValid
@@ -2257,7 +2262,7 @@ OEMCryptoResult OEMCrypto_IsKeyboxOrOEMCertValid(void);
  *   system upgrade.
  *
  *   This function is optional but recommended for Provisioning 3.0 in API v15.
- *   It may be required for future version of this API.
+ *   It may be required for a future version of this API.
  *
  * Parameters:
  *   [out] deviceId - pointer to the buffer that receives the Device ID
@@ -2459,7 +2464,7 @@ OEMCryptoResult OEMCrypto_GetRandom(uint8_t* randomData, size_t dataLength);
  * Version:
  *   This method changed in each API version.
  */
-uint32_t OEMCrypto_APIVersion();
+uint32_t OEMCrypto_APIVersion(void);
 
 /*
  * OEMCrypto_BuildInformation
@@ -2497,7 +2502,7 @@ uint32_t OEMCrypto_APIVersion();
  * Version:
  *   This method changed in each API version.
  */
-const char* OEMCrypto_BuildInformation();
+const char* OEMCrypto_BuildInformation(void);
 
 /*
  * OEMCrypto_Security_Patch_Level
@@ -2524,7 +2529,7 @@ const char* OEMCrypto_BuildInformation();
  * Version:
  *   This method was introduced in API version 11.
  */
-uint8_t OEMCrypto_Security_Patch_Level();
+uint8_t OEMCrypto_Security_Patch_Level(void);
 
 /*
  * OEMCrypto_SecurityLevel
@@ -2550,7 +2555,7 @@ uint8_t OEMCrypto_Security_Patch_Level();
  * Version:
  *   This method changed in API version 6.
  */
-const char* OEMCrypto_SecurityLevel();
+const char* OEMCrypto_SecurityLevel(void);
 
 /*
  * OEMCrypto_GetHDCPCapability
@@ -2565,12 +2570,6 @@ const char* OEMCrypto_SecurityLevel();
  *   instead of HDMI output. Notice that HDCP must use flag Type 1: all
  *   downstream devices will also use the same version or higher.
  *
- *   The current HDCP should be the minimum value of any display currently
- *   connected through any channel, either through HDMI or a supported wireless
- *   format. The current value can be used by the application or server to
- *   decide which license can currently be used. If the key control block
- *   requires the current HDCP level, we expect the key to be usable.
- *
  *   The maximum HDCP level should be the maximum value that the device can
  *   enforce. For example, if the device has an HDCP 1.0 port and an HDCP 2.0
  *   port, and the first port can be disabled, then the maximum is HDCP 2.0. If
@@ -2581,6 +2580,30 @@ const char* OEMCrypto_SecurityLevel();
  *   user intends to view the content on a local display. The user will want to
  *   download the higher quality content.
  *
+ *   The current HDCP level should be the level of HDCP currently negotiated
+ *   with any connected receivers or repeaters either through HDMI or a
+ *   supported wireless format. If multiple ports are connected, the current
+ *   level should be the minimum HDCP level of all ports. If the key control
+ *   block requires an HDCP level equal to or lower than the current HDCP
+ *   level, the key is expected to be usable. If the key control block requires
+ *   a higher HDCP level, the key is expected to be forbidden.
+ *
+ *   When a key has version HDCP_V2_3 required in the key control block, the
+ *   transmitter must have HDCP version 2.3 and have negotiated a connection
+ *   with a version 2.3 receiver or repeater. The transmitter must configure
+ *   the content stream to be Type 1. Since the transmitter cannot distinguish
+ *   between 2.2 and 2.3 downstream receivers when connected to a repeater, it
+ *   may transmit to both 2.2 and 2.3 receivers, but not 2.1 receivers.
+ *
+ *   For example, if the transmitter is 2.3, and is connected to a receiver
+ *   that supports 2.3 then the current level is HDCP_V2_3. If the transmitter
+ *   is 2.3 and is connected to a 2.3 repeater, the current level is HDCP_V2_3
+ *   even though  the repeater can negotiate a connection with a 2.2 downstream
+ *   receiver for a Type 1 Content Stream.
+ *
+ *   As another example, if the transmitter can support 2.3, but a receiver
+ *   supports 2.0, then the current level is HDCP_V2.
+ *
  *   When a license requires HDCP, a device may use a wireless protocol to
  *   connect to a display only if that protocol supports the version of HDCP as
  *   required by the license. Both WirelessHD (formerly WiFi Display) and
@@ -2633,7 +2656,7 @@ OEMCryptoResult OEMCrypto_GetHDCPCapability(OEMCrypto_HDCP_Capability* current,
  * Version:
  *   This method changed in API version 9.
  */
-bool OEMCrypto_SupportsUsageTable();
+bool OEMCrypto_SupportsUsageTable(void);
 
 /*
  * OEMCrypto_IsAntiRollbackHwPresent
@@ -2661,7 +2684,7 @@ bool OEMCrypto_SupportsUsageTable();
  * Version:
  *   This method is new in API version 10.
  */
-bool OEMCrypto_IsAntiRollbackHwPresent();
+bool OEMCrypto_IsAntiRollbackHwPresent(void);
 
 /*
  * OEMCrypto_GetNumberOfOpenSessions
@@ -2762,7 +2785,7 @@ OEMCryptoResult OEMCrypto_GetMaxNumberOfSessions(size_t* max);
  * Version:
  *   This method changed in API version 13.
  */
-uint32_t OEMCrypto_SupportedCertificates();
+uint32_t OEMCrypto_SupportedCertificates(void);
 
 /*
  * OEMCrypto_IsSRMUpdateSupported
@@ -2789,7 +2812,7 @@ uint32_t OEMCrypto_SupportedCertificates();
  * Version:
  *   This method changed in API version 13.
  */
-bool OEMCrypto_IsSRMUpdateSupported();
+bool OEMCrypto_IsSRMUpdateSupported(void);
 
 /*
  * OEMCrypto_GetCurrentSRMVersion
@@ -2856,7 +2879,7 @@ OEMCryptoResult OEMCrypto_GetCurrentSRMVersion(uint16_t* version);
  * Version:
  *   This method is new in API version 14.
  */
-uint32_t OEMCrypto_GetAnalogOutputFlags();
+uint32_t OEMCrypto_GetAnalogOutputFlags(void);
 
 /*
  * OEMCrypto_ResourceRatingTier
@@ -2865,7 +2888,7 @@ uint32_t OEMCrypto_GetAnalogOutputFlags();
  *   This function returns a positive number indicating which resource rating
  *   it supports. This value will bubble up to the application level as a
  *   property. This will allow applications to estimate what resolution and
- *   bandwidth the device expects to support.
+ *   bandwidth the device is expected to support.
  *
  *   OEMCrypto unit tests and Android GTS tests will verify that devices do
  *   support the resource values specified in the table below at the tier
@@ -2925,8 +2948,6 @@ uint32_t OEMCrypto_GetAnalogOutputFlags();
  *   +-----------------------------------+-----------+------------+-----------+
  *   |Number of keys per session         |4          |20          |20         |
  *   +-----------------------------------+-----------+------------+-----------+
- *   |Simultaneous secure playback       |1          |2           |2          |
- *   +-----------------------------------+-----------+------------+-----------+
  *   |Decrypted Frames per Second        |30 fps SD  |30 fps HD   |60 fps HD  |
  *   +-----------------------------------+-----------+------------+-----------+
  *
@@ -2945,7 +2966,7 @@ uint32_t OEMCrypto_GetAnalogOutputFlags();
  * Version:
  *   This method is new in API version 15.
  */
-uint32_t OEMCrypto_ResourceRatingTier();
+uint32_t OEMCrypto_ResourceRatingTier(void);
 
 /*
  * OEMCrypto_RewrapDeviceRSAKey30
@@ -3306,7 +3327,7 @@ OEMCryptoResult OEMCrypto_LoadDeviceRSAKey(OEMCrypto_SESSION session,
  * Version:
  *   This method is new in API version 10.
  */
-OEMCryptoResult OEMCrypto_LoadTestRSAKey();
+OEMCryptoResult OEMCrypto_LoadTestRSAKey(void);
 
 /*
  * OEMCrypto_GenerateRSASignature
@@ -3648,8 +3669,10 @@ OEMCryptoResult OEMCrypto_UpdateUsageEntry(OEMCrypto_SESSION session,
  *   means that the state of the usage entry is changed to InactiveUsed if it
  *   was Active, or InactiveUnused if it was Unused. This also increments the
  *   entry's generation number, and the header's master generation number. The
- *   entry's flag ForbidReport will be set. This flag prevents an application
- *   from generating a report of a deactivated license without first saving the
+ *   corresponding generation number in the usage table header is also
+ *   incremented so that it matches the one in the entry. The entry's flag
+ *   ForbidReport will be set. This flag prevents an application from
+ *   generating a report of a deactivated license without first saving the
  *   entry.
  *
  *   It is allowed to call this function multiple times. If the state is
@@ -3954,14 +3977,14 @@ OEMCryptoResult OEMCrypto_CopyOldUsageEntry(OEMCrypto_SESSION session,
  * Version:
  *   This method is new in API version 13.
  */
-OEMCryptoResult OEMCrypto_DeleteOldUsageTable();
+OEMCryptoResult OEMCrypto_DeleteOldUsageTable(void);
 
 /*
  * OEMCrypto_RemoveSRM
  *
  * Description:
- *   Delete the current SRM. Any valid SRM, regardless of version number, will
- *   be installable after this via OEMCrypto_LoadSRM.
+ *   Delete the current SRM. Any valid SRM, regardless of its version number,
+ *   will be installable after this via OEMCrypto_LoadSRM.
  *
  *   This function should not be implemented on production devices, and will
  *   only be used to verify unit tests on a test device.
@@ -3981,7 +4004,7 @@ OEMCryptoResult OEMCrypto_DeleteOldUsageTable();
  * Version:
  *   This method is new in API version 13.
  */
-OEMCryptoResult OEMCrypto_RemoveSRM();
+OEMCryptoResult OEMCrypto_RemoveSRM(void);
 
 /*
  * OEMCrypto_CreateOldUsageEntry
@@ -4027,7 +4050,7 @@ OEMCryptoResult OEMCrypto_CreateOldUsageEntry(uint64_t time_since_license_receiv
  *   supported. OEMCrypto is not required by Google to support this feature,
  *   but support will greatly improve automated testing. A hash type of
  *   OEMCrypto_CRC_Clear_Buffer = 1 means the device will be able to compute
- *   the CRC32 checksum of the decrypted content in the secure buffer after a
+ *   the CRC 32 checksum of the decrypted content in the secure buffer after a
  *   call to OEMCrypto_DecryptCENC. Google intends to provide test applications
  *   on some platforms, such as Android, that will automate decryption testing
  *   using the CRC 32 checksum of all frames in some test content.
@@ -4055,7 +4078,7 @@ OEMCryptoResult OEMCrypto_CreateOldUsageEntry(uint64_t time_since_license_receiv
  * Version:
  *   This method is new in API version 15.
  */
-uint32_t OEMCrypto_SupportsDecryptHash();
+uint32_t OEMCrypto_SupportsDecryptHash(void);
 
 /*
  * OEMCrypto_SetDecryptHash
diff --git a/oemcrypto/ref/src/oemcrypto_engine_ref.cpp b/oemcrypto/ref/src/oemcrypto_engine_ref.cpp
index 2c6e6b5..82b88de 100644
--- a/oemcrypto/ref/src/oemcrypto_engine_ref.cpp
+++ b/oemcrypto/ref/src/oemcrypto_engine_ref.cpp
@@ -182,6 +182,14 @@ time_t CryptoEngine::RollbackCorrectedOfflineTime() {
   return current_time;
 }
 
+bool CryptoEngine::NonceCollision(uint32_t nonce) {
+  for (const auto & session_pair :  sessions_) {
+    const SessionContext* session = session_pair.second;
+    if (session->NonceCollision(nonce)) return true;
+  }
+  return false;
+}
+
 OEMCrypto_HDCP_Capability CryptoEngine::config_current_hdcp_capability() {
   return config_local_display_only() ? HDCP_NO_DIGITAL_OUTPUT : HDCP_V1;
 }
diff --git a/oemcrypto/ref/src/oemcrypto_engine_ref.h b/oemcrypto/ref/src/oemcrypto_engine_ref.h
index 6ad5cd2..cc132aa 100644
--- a/oemcrypto/ref/src/oemcrypto_engine_ref.h
+++ b/oemcrypto/ref/src/oemcrypto_engine_ref.h
@@ -91,6 +91,10 @@ class CryptoEngine {
 
   time_t RollbackCorrectedOfflineTime();
 
+  // Verify that this nonce does not collide with another nonce in any session's
+  // nonce table.
+  virtual bool NonceCollision(uint32_t nonce);
+
   // Returns the HDCP version currently in use.
   virtual OEMCrypto_HDCP_Capability config_current_hdcp_capability();
 
diff --git a/oemcrypto/ref/src/oemcrypto_nonce_table.cpp b/oemcrypto/ref/src/oemcrypto_nonce_table.cpp
index 19c7613..65d9269 100644
--- a/oemcrypto/ref/src/oemcrypto_nonce_table.cpp
+++ b/oemcrypto/ref/src/oemcrypto_nonce_table.cpp
@@ -58,6 +58,13 @@ bool NonceTable::CheckNonce(uint32_t nonce) {
   return false;
 }
 
+bool NonceTable::NonceCollision(uint32_t nonce) const {
+  for (int i = 0; i < kTableSize; ++i) {
+    if (nonce == nonces_[i]) return true;
+  }
+  return false;
+}
+
 void NonceTable::Flush() {
   for (int i = 0; i < kTableSize; ++i) {
     if (kNTStateFlushPending == state_[i]) {
diff --git a/oemcrypto/ref/src/oemcrypto_nonce_table.h b/oemcrypto/ref/src/oemcrypto_nonce_table.h
index 90175e2..409e7fc 100644
--- a/oemcrypto/ref/src/oemcrypto_nonce_table.h
+++ b/oemcrypto/ref/src/oemcrypto_nonce_table.h
@@ -13,7 +13,7 @@ namespace wvoec_ref {
 
 class NonceTable {
  public:
-  static const int kTableSize = 16;
+  static const int kTableSize = 4;
   NonceTable() {
     for (int i = 0; i < kTableSize; ++i) {
       state_[i] = kNTStateInvalid;
@@ -22,6 +22,8 @@ class NonceTable {
   ~NonceTable() {}
   void AddNonce(uint32_t nonce);
   bool CheckNonce(uint32_t nonce);
+  // Verify that the nonce is not the same as any in this table.
+  bool NonceCollision(uint32_t nonce) const;
   void Flush();
 
  private:
diff --git a/oemcrypto/ref/src/oemcrypto_ref.cpp b/oemcrypto/ref/src/oemcrypto_ref.cpp
index 67d3e12..355fbf7 100644
--- a/oemcrypto/ref/src/oemcrypto_ref.cpp
+++ b/oemcrypto/ref/src/oemcrypto_ref.cpp
@@ -189,13 +189,15 @@ OEMCRYPTO_API OEMCryptoResult OEMCrypto_GenerateNonce(OEMCrypto_SESSION session,
     last_nonce_time = now;
   }
 
-  uint32_t nonce_value;
+  uint32_t nonce_value = 0;
   uint8_t* nonce_string = reinterpret_cast<uint8_t*>(&nonce_value);
 
-  // Generate 4 bytes of random data
-  if (!RAND_bytes(nonce_string, 4)) {
-    LOGE("[OEMCrypto_GenerateNonce(): Random bytes failure]");
-    return OEMCrypto_ERROR_UNKNOWN_FAILURE;
+  while (nonce_value == 0 || crypto_engine->NonceCollision(nonce_value)) {
+    // Generate 4 bytes of random data
+    if (!RAND_bytes(nonce_string, 4)) {
+      LOGE("[OEMCrypto_GenerateNonce(): Random bytes failure]");
+      return OEMCrypto_ERROR_UNKNOWN_FAILURE;
+    }
   }
   session_ctx->AddNonce(nonce_value);
   *nonce = nonce_value;
@@ -281,9 +283,8 @@ OEMCRYPTO_API OEMCryptoResult OEMCrypto_LoadKeys(
       !RangeCheck(message_length, enc_mac_keys, true) ||
       !RangeCheck(message_length, pst, true) ||
       !RangeCheck(message_length, srm_restriction_data, true)) {
-    LOGE(
-        "[OEMCrypto_LoadKeys(): OEMCrypto_ERROR_INVALID_CONTEXT - range "
-        "check.]");
+    LOGE("[OEMCrypto_LoadKeys(): OEMCrypto_ERROR_INVALID_CONTEXT - "
+         "range check.]");
     return OEMCrypto_ERROR_INVALID_CONTEXT;
   }
 
@@ -293,13 +294,25 @@ OEMCRYPTO_API OEMCryptoResult OEMCrypto_LoadKeys(
         !RangeCheck(message_length, key_array[i].key_data_iv, false) ||
         !RangeCheck(message_length, key_array[i].key_control, false) ||
         !RangeCheck(message_length, key_array[i].key_control_iv, false)) {
-      LOGE(
-          "[OEMCrypto_LoadKeys(): OEMCrypto_ERROR_INVALID_CONTEXT -range "
-          "check %d]",
-          i);
+      LOGE("[OEMCrypto_LoadKeys(): OEMCrypto_ERROR_INVALID_CONTEXT - "
+           "range check %d]", i);
       return OEMCrypto_ERROR_INVALID_CONTEXT;
     }
   }
+  if (enc_mac_keys.offset >= wvoec::KEY_IV_SIZE && enc_mac_keys.length > 0) {
+    if (enc_mac_keys_iv.offset + wvoec::KEY_IV_SIZE == enc_mac_keys.offset) {
+      LOGE("[OEMCrypto_LoadKeys(): OEMCrypto_ERROR_INVALID_CONTEXT - "
+           "range check iv]");
+      return OEMCrypto_ERROR_INVALID_CONTEXT;
+    } else {
+      if (memcmp(message + enc_mac_keys.offset - wvoec::KEY_IV_SIZE,
+                 message + enc_mac_keys_iv.offset, wvoec::KEY_IV_SIZE) == 0) {
+        LOGE("[OEMCrypto_LoadKeys(): OEMCrypto_ERROR_INVALID_CONTEXT - "
+             "suspicious iv]");
+        return OEMCrypto_ERROR_INVALID_CONTEXT;
+      }
+    }
+  }
   return session_ctx->LoadKeys(message, message_length, signature,
                                signature_length, enc_mac_keys_iv, enc_mac_keys,
                                num_keys, key_array, pst, srm_restriction_data,
diff --git a/oemcrypto/ref/src/oemcrypto_scoped_ptr.h b/oemcrypto/ref/src/oemcrypto_scoped_ptr.h
deleted file mode 100644
index 8e56fa0..0000000
--- a/oemcrypto/ref/src/oemcrypto_scoped_ptr.h
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright 2018 Google LLC. All Rights Reserved. This file and proprietary
-// source code may only be used and distributed under the Widevine Master
-// License Agreement.
-#ifndef OEMCRYPTO_SCOPED_PTR_H_
-#define OEMCRYPTO_SCOPED_PTR_H_
-
-#include <stddef.h>
-#include <memory>
-
-#include <arpa/inet.h>
-
-namespace wvoec_ref {
-
-// TODO(fredgc, jfore): scoped_ptr may not be the best name for this smart
-// pointer type. It basically works like auto_ptr which is deprecated.
-#if __cplusplus < 201103L
-
-template <typename T>
-class scoped_ptr {
- public:
-  explicit scoped_ptr(T* p = NULL) : ptr_(p) {}
-  T* get() const { return ptr_.get(); }
-  void reset(T* p = NULL) { ptr_.reset(p); }
-
- private:
-  std::auto_ptr<T> ptr_;
-};
-
-#else
-
-template <typename T>
-class scoped_ptr {
- public:
-  explicit scoped_ptr(T* p = nullptr) : ptr_(p) {}
-  scoped_ptr(scoped_ptr& r) { ptr_ = std::move(r.ptr_); }
-  T& operator*() const { return *ptr_; }
-  T* operator->() const { return ptr_.get(); }
-  T* get() const { return ptr_.get(); }
-  void reset(T* p = NULL) { ptr_.reset(p); }
-
- private:
-  std::unique_ptr<T> ptr_;
-};
-#endif
-
-}  // namespace wvoec_ref
-
-#endif  // OEMCRYPTO_SCOPED_PTR_H_
diff --git a/oemcrypto/ref/src/oemcrypto_session.cpp b/oemcrypto/ref/src/oemcrypto_session.cpp
index 714b252..eb70320 100644
--- a/oemcrypto/ref/src/oemcrypto_session.cpp
+++ b/oemcrypto/ref/src/oemcrypto_session.cpp
@@ -636,6 +636,7 @@ OEMCryptoResult SessionContext::LoadKeys(
         break;
     }
   }
+  encryption_key_.clear();
   return OEMCrypto_SUCCESS;
 }
 
diff --git a/oemcrypto/ref/src/oemcrypto_session.h b/oemcrypto/ref/src/oemcrypto_session.h
index bfd81a6..0956056 100644
--- a/oemcrypto/ref/src/oemcrypto_session.h
+++ b/oemcrypto/ref/src/oemcrypto_session.h
@@ -173,6 +173,10 @@ class SessionContext {
 
   void AddNonce(uint32_t nonce);
   bool CheckNonce(uint32_t nonce);
+  // Verify that the nonce does not match any in this session's nonce table.
+  bool NonceCollision(uint32_t nonce) const {
+    return nonce_table_.NonceCollision(nonce);
+  }
   void FlushNonces();
 
   virtual OEMCryptoResult CreateNewUsageEntry(uint32_t* usage_entry_number);
diff --git a/oemcrypto/test/oec_device_features.cpp b/oemcrypto/test/oec_device_features.cpp
index bad4c55..2e18ca1 100644
--- a/oemcrypto/test/oec_device_features.cpp
+++ b/oemcrypto/test/oec_device_features.cpp
@@ -153,33 +153,12 @@ std::string DeviceFeatures::RestrictFilter(const std::string& initial_filter) {
   if (provisioning_method
       != OEMCrypto_OEMCertificate)    FilterOut(&filter, "*Prov30*");
   if (!supports_rsa_3072)             FilterOut(&filter, "*RSAKey3072*");
-  if (api_version < 14) {
-    // Because API 13 uses an old hard coded test keybox, none of these tests
-    // will pass.  Partners who wish to test with a v13 OEMCrypto should use
-    // code on an older v13 branch.
-    printf("These unit tests are designed for OEMCrypto API 15 and above.\n");
-    printf("This device has an OEMCrypto with API version %d.\n", api_version);
-    printf("To verify correctness, please build unit tests from a "
-         "compatible branch.\n");
-    FilterOut(&filter, "*API09*");
-    FilterOut(&filter, "*API10*");
-    FilterOut(&filter, "*API11*");
-    FilterOut(&filter, "*API12*");
-    FilterOut(&filter, "*API13*");
-    FilterOut(&filter, "*API14*");
-    FilterOut(&filter, "*TestKeyboxTest*");
-    FilterOut(&filter, "*SessionTest*");
-    FilterOut(&filter, "*UsageTable*");
-    FilterOut(&filter, "*GenericCrypto*");
-    FilterOut(&filter, "*LoadsCertificate*");
-    FilterOut(&filter, "*UsesCertificate*");
-    // We also expect some CDM tests to fail without a new test keybox:
-    FilterOut(&filter, "*WvCdmRequestLicenseTest*");
-    FilterOut(&filter, "*WvGenericOperations*");
-    FilterOut(&filter, "*WvCdmEngine*");
-    FilterOut(&filter, "*Cdm/WvCdm*");
-    FilterOut(&filter, "*Cdm/WvHls*");
-  }
+  if (api_version <  9)               FilterOut(&filter, "*API09*");
+  if (api_version < 10)               FilterOut(&filter, "*API10*");
+  if (api_version < 11)               FilterOut(&filter, "*API11*");
+  if (api_version < 12)               FilterOut(&filter, "*API12*");
+  if (api_version < 13)               FilterOut(&filter, "*API13*");
+  if (api_version < 14)               FilterOut(&filter, "*API14*");
   if (api_version < 15)               FilterOut(&filter, "*API15*");
   // Some tests may require root access. If user is not root, filter these tests
   // out.
diff --git a/oemcrypto/test/oec_session_util.cpp b/oemcrypto/test/oec_session_util.cpp
index 4ed98c5..737f473 100644
--- a/oemcrypto/test/oec_session_util.cpp
+++ b/oemcrypto/test/oec_session_util.cpp
@@ -539,6 +539,7 @@ void Session::FillSimpleMessage(uint32_t duration, uint32_t control,
                                 uint32_t nonce, const std::string& pst) {
   EXPECT_EQ(
       1, GetRandBytes(license_.mac_key_iv, sizeof(license_.mac_key_iv)));
+  memset(license_.padding, 0, sizeof(license_.padding));
   EXPECT_EQ(1, GetRandBytes(license_.mac_keys, sizeof(license_.mac_keys)));
   for (unsigned int i = 0; i < num_keys_; i++) {
     memset(license_.keys[i].key_id, 0, kTestKeyIdMaxLength);
@@ -1268,7 +1269,6 @@ void Session::GenerateReport(const std::string& pst,
     ASSERT_EQ(OEMCrypto_ERROR_SHORT_BUFFER, sts);
   }
   if (sts == OEMCrypto_ERROR_SHORT_BUFFER) {
-    ASSERT_EQ(wvcdm::Unpacked_PST_Report::report_size(pst.length()), length);
     pst_report_buffer_.assign(length, 0xFF);  // Fill with garbage values.
   }
   sts = OEMCrypto_ReportUsage(session_id(),
@@ -1278,7 +1278,7 @@ void Session::GenerateReport(const std::string& pst,
   if (expected_result != OEMCrypto_SUCCESS) {
     return;
   }
-  ASSERT_EQ(pst_report_buffer_.size(), length);
+  EXPECT_EQ(wvcdm::Unpacked_PST_Report::report_size(pst.length()), length);
   vector<uint8_t> computed_signature(SHA_DIGEST_LENGTH);
   unsigned int sig_len = SHA_DIGEST_LENGTH;
   HMAC(EVP_sha1(), mac_key_client_.data(), mac_key_client_.size(),
@@ -1359,6 +1359,9 @@ void Session::GenerateVerifyReport(const std::string& pst,
   Test_PST_Report expected(pst, status);
   ASSERT_NO_FATAL_FAILURE(VerifyReport(expected, time_license_received,
                                        time_first_decrypt, time_last_decrypt));
+  // The PST report was signed above.  Below we verify that the entire message
+  // that is sent to the server will be signed by the right mac keys.
+  ASSERT_NO_FATAL_FAILURE(VerifyClientSignature());
 }
 
 void Session::CreateOldEntry(const Test_PST_Report& report) {
diff --git a/oemcrypto/test/oec_session_util.h b/oemcrypto/test/oec_session_util.h
index 4f1ab1b..f162760 100644
--- a/oemcrypto/test/oec_session_util.h
+++ b/oemcrypto/test/oec_session_util.h
@@ -81,6 +81,7 @@ typedef struct {
 struct MessageData {
   MessageKeyData keys[kMaxNumKeys];
   uint8_t mac_key_iv[KEY_IV_SIZE];
+  uint8_t padding[KEY_IV_SIZE];
   uint8_t mac_keys[2 * MAC_KEY_SIZE];
   uint8_t pst[kMaxPSTLength];
 };
diff --git a/oemcrypto/test/oec_test_data.h b/oemcrypto/test/oec_test_data.h
index 144c4d3..9739144 100644
--- a/oemcrypto/test/oec_test_data.h
+++ b/oemcrypto/test/oec_test_data.h
@@ -15,6 +15,41 @@
 
 namespace wvoec {
 
+// TODO(fredgc, b/119316243): REMOVE THIS KEYBOX!
+// This test keybox is used for testing with OEMCrypto v13.
+// It should be removed before release!
+static const WidevineKeybox kTestKeyboxForV13 = {
+  // Sample keybox used for test vectors
+  {
+    // deviceID
+    0x54, 0x65, 0x73, 0x74, 0x4b, 0x65, 0x79, 0x30,  // TestKey01
+    0x31, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // ........
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // ........
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // ........
+  }, {
+    // key
+    0xfb, 0xda, 0x04, 0x89, 0xa1, 0x58, 0x16, 0x0e,
+    0xa4, 0x02, 0xe9, 0x29, 0xe3, 0xb6, 0x8f, 0x04,
+  }, {
+    // data
+    0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x10, 0x19,
+    0x07, 0xd9, 0xff, 0xde, 0x13, 0xaa, 0x95, 0xc1,
+    0x22, 0x67, 0x80, 0x53, 0x36, 0x21, 0x36, 0xbd,
+    0xf8, 0x40, 0x8f, 0x82, 0x76, 0xe4, 0xc2, 0xd8,
+    0x7e, 0xc5, 0x2b, 0x61, 0xaa, 0x1b, 0x9f, 0x64,
+    0x6e, 0x58, 0x73, 0x49, 0x30, 0xac, 0xeb, 0xe8,
+    0x99, 0xb3, 0xe4, 0x64, 0x18, 0x9a, 0x14, 0xa8,
+    0x72, 0x02, 0xfb, 0x02, 0x57, 0x4e, 0x70, 0x64,
+    0x0b, 0xd2, 0x2e, 0xf4, 0x4b, 0x2d, 0x7e, 0x39,
+  }, {
+    // magic
+    0x6b, 0x62, 0x6f, 0x78,
+  }, {
+    // Crc
+    0x0a, 0x7a, 0x2c, 0x35,
+  }
+};
+
 // This is a test keybox.  It will not be accepted by production systems.  By
 // using a known keybox for these tests, the results for a given set of inputs
 // to a test are predictable and can be compared to the actual results.
diff --git a/oemcrypto/test/oemcrypto_session_tests_helper.cpp b/oemcrypto/test/oemcrypto_session_tests_helper.cpp
index 60eb36a..c9643b8 100644
--- a/oemcrypto/test/oemcrypto_session_tests_helper.cpp
+++ b/oemcrypto/test/oemcrypto_session_tests_helper.cpp
@@ -105,6 +105,8 @@ void SessionUtil::EnsureTestKeys() {
   switch (global_features.derive_key_method) {
     case DeviceFeatures::LOAD_TEST_KEYBOX:
       keybox_ = kTestKeybox;
+      // TODO(fredgc, b/119316243): REMOVE FOLLOWING LINE:
+      if (global_features.api_version < 14) keybox_ = kTestKeyboxForV13;
       ASSERT_EQ(OEMCrypto_SUCCESS,
                 OEMCrypto_LoadTestKeybox(
                     reinterpret_cast<const uint8_t*>(&keybox_),
diff --git a/oemcrypto/test/oemcrypto_test.cpp b/oemcrypto/test/oemcrypto_test.cpp
index 21da261..3df68bf 100644
--- a/oemcrypto/test/oemcrypto_test.cpp
+++ b/oemcrypto/test/oemcrypto_test.cpp
@@ -871,6 +871,24 @@ TEST_F(OEMCryptoSessionTests, LoadKeyNoNonce) {
   ASSERT_NO_FATAL_FAILURE(s.LoadTestKeys());
 }
 
+// Verify that a second license may be not be loaded in a session.
+TEST_F(OEMCryptoSessionTests, LoadKeyNoNonceTwice) {
+  Session s;
+  ASSERT_NO_FATAL_FAILURE(s.open());
+  ASSERT_NO_FATAL_FAILURE(InstallTestSessionKeys(&s));
+  ASSERT_NO_FATAL_FAILURE(s.FillSimpleMessage(kDuration, 0, 42));
+  ASSERT_NO_FATAL_FAILURE(s.EncryptAndSign());
+  ASSERT_NO_FATAL_FAILURE(s.LoadTestKeys());
+  ASSERT_NO_FATAL_FAILURE(s.EncryptAndSign());
+  ASSERT_NE(
+      OEMCrypto_SUCCESS,
+      OEMCrypto_LoadKeys(s.session_id(), s.message_ptr(), s.message_size(),
+                         s.signature().data(), s.signature().size(),
+                         s.enc_mac_keys_iv_substr(), s.enc_mac_keys_substr(),
+                         s.num_keys(), s.key_array(), s.pst_substr(),
+                         GetSubstring(), OEMCrypto_ContentLicense));
+}
+
 // Verify that a license may be loaded with a nonce.
 TEST_F(OEMCryptoSessionTests, LoadKeyWithNonce) {
   Session s;
@@ -882,6 +900,24 @@ TEST_F(OEMCryptoSessionTests, LoadKeyWithNonce) {
   ASSERT_NO_FATAL_FAILURE(s.LoadTestKeys());
 }
 
+// Verify that a second license may be not be loaded in a session.
+TEST_F(OEMCryptoSessionTests, LoadKeyWithNonceTwice) {
+  Session s;
+  ASSERT_NO_FATAL_FAILURE(s.open());
+  ASSERT_NO_FATAL_FAILURE(InstallTestSessionKeys(&s));
+  ASSERT_NO_FATAL_FAILURE(
+      s.FillSimpleMessage(0, wvoec::kControlNonceEnabled, s.get_nonce()));
+  ASSERT_NO_FATAL_FAILURE(s.EncryptAndSign());
+  ASSERT_NO_FATAL_FAILURE(s.LoadTestKeys());
+  ASSERT_NE(
+      OEMCrypto_SUCCESS,
+      OEMCrypto_LoadKeys(s.session_id(), s.message_ptr(), s.message_size(),
+                         s.signature().data(), s.signature().size(),
+                         s.enc_mac_keys_iv_substr(), s.enc_mac_keys_substr(),
+                         s.num_keys(), s.key_array(), s.pst_substr(),
+                         GetSubstring(), OEMCrypto_ContentLicense));
+}
+
 // This asks for several nonce.  This simulates several license requests being
 // lost.  OEMCrypto is required to keep up to four nonce in the nonce table.
 TEST_F(OEMCryptoSessionTests, LoadKeySeveralNonce) {
@@ -1179,6 +1215,27 @@ TEST_F(OEMCryptoSessionTests, LoadKeyWithBadRange7) {
   ASSERT_NE(OEMCrypto_SUCCESS, sts);
 }
 
+// The IV should not be identical to the data right before the encrypted mac
+// keys.
+TEST_F(OEMCryptoSessionTests, LoadKeyWithSuspiciousIV) {
+  Session s;
+  ASSERT_NO_FATAL_FAILURE(s.open());
+  ASSERT_NO_FATAL_FAILURE(InstallTestSessionKeys(&s));
+  ASSERT_NO_FATAL_FAILURE(s.FillSimpleMessage(0, 0, 0));
+  // This is suspicious: the data right before the mac keys is identical to the
+  // iv.
+  memcpy(s.license().padding, s.license().mac_key_iv,
+         sizeof(s.license().padding));
+  ASSERT_NO_FATAL_FAILURE(s.EncryptAndSign());
+
+  OEMCryptoResult sts = OEMCrypto_LoadKeys(
+      s.session_id(), s.message_ptr(), s.message_size(), s.signature().data(),
+      s.signature().size(), s.enc_mac_keys_iv_substr(), s.enc_mac_keys_substr(),
+      s.num_keys(), s.key_array(), GetSubstring(), GetSubstring(),
+      OEMCrypto_ContentLicense);
+  ASSERT_NE(OEMCrypto_SUCCESS, sts);
+}
+
 // Test that LoadKeys fails when a key is loaded with no key control block.
 TEST_F(OEMCryptoSessionTests, LoadKeyWithNullKeyControl) {
   Session s;
@@ -5396,9 +5453,9 @@ TEST_P(UsageTableTestWithMAC, ReloadOfflineLicenseWithRefresh) {
   ASSERT_NO_FATAL_FAILURE(s.close());
 }
 
-// Verify that a license that has been we can still reload an offline license
-// after OEMCrypto_Terminate and Initialize are called. This is as close to a
-// reboot as we can do in a unit test.
+// Verify that we can still reload an offline license after OEMCrypto_Terminate
+// and Initialize are called. This is as close to a reboot as we can do in a
+// unit test.
 TEST_P(UsageTableTestWithMAC, ReloadOfflineLicenseWithTerminate) {
   std::string pst = "my_pst";
   Session s;
diff --git a/oemcrypto/test/oemcrypto_test_android.cpp b/oemcrypto/test/oemcrypto_test_android.cpp
index 7dd3384..e0739ea 100644
--- a/oemcrypto/test/oemcrypto_test_android.cpp
+++ b/oemcrypto/test/oemcrypto_test_android.cpp
@@ -50,6 +50,11 @@ TEST_F(OEMCryptoAndroidLMPTest, ValidKeybox) {
   }
 }
 
+TEST_F(OEMCryptoAndroidLMPTest, MinVersionNumber9) {
+  uint32_t version = OEMCrypto_APIVersion();
+  ASSERT_LE(9u, version);
+}
+
 TEST_F(OEMCryptoAndroidLMPTest, ValidKeyboxTest) {
   ASSERT_EQ(OEMCrypto_SUCCESS, OEMCrypto_IsKeyboxValid());
 }
@@ -108,6 +113,11 @@ TEST_F(OEMCryptoAndroidLMPTest, Level1Required) {
 // These tests are required for M Android devices.
 class OEMCryptoAndroidMNCTest : public OEMCryptoAndroidLMPTest {};
 
+TEST_F(OEMCryptoAndroidMNCTest, MinVersionNumber10) {
+  uint32_t version = OEMCrypto_APIVersion();
+  ASSERT_GE(version, 10u);
+}
+
 // Android devices using Provisioning 2.0 must be able to load a test keybox.
 // If they are not using Provisioning 2.0, then they must use Provisioning 3.0.
 TEST_F(OEMCryptoAndroidMNCTest, LoadsTestKeyboxImplemented) {
@@ -135,4 +145,28 @@ TEST_F(OEMCryptoAndroidMNCTest, QueryKeyControlImplemented) {
             OEMCrypto_QueryKeyControl(0, NULL, 0, NULL, NULL));
 }
 
+// These tests are required for N Android devices.
+class OEMCryptoAndroidNYCTest : public OEMCryptoAndroidMNCTest {};
+
+TEST_F(OEMCryptoAndroidNYCTest, MinVersionNumber11) {
+  uint32_t version = OEMCrypto_APIVersion();
+  ASSERT_GE(version, 11u);
+}
+
+// These tests are required for O MR1 Android devices.
+class OEMCryptoAndroidOCTest : public OEMCryptoAndroidNYCTest {};
+
+TEST_F(OEMCryptoAndroidOCTest, MinVersionNumber13) {
+  uint32_t version = OEMCrypto_APIVersion();
+  ASSERT_GE(version, 13u);
+}
+
+// These tests are required for Q Android devices.
+class OEMCryptoAndroidQTest : public OEMCryptoAndroidOCTest {};
+
+TEST_F(OEMCryptoAndroidQTest, MinVersionNumber14) {
+  uint32_t version = OEMCrypto_APIVersion();
+  ASSERT_GE(version, 15u);
+}
+
 }  // namespace wvoec
diff --git a/util/include/lock.h b/util/include/lock.h
deleted file mode 100644
index 3eb288f..0000000
--- a/util/include/lock.h
+++ /dev/null
@@ -1,53 +0,0 @@
-// Copyright 2018 Google LLC. All Rights Reserved. This file and proprietary
-// source code may only be used and distributed under the Widevine Master
-// License Agreement.
-//
-// Lock - Platform independent interface for a Mutex class
-//
-#ifndef WVCDM_UTIL_LOCK_H_
-#define WVCDM_UTIL_LOCK_H_
-
-#include "disallow_copy_and_assign.h"
-
-namespace wvcdm {
-
-// Simple lock class. The implementation is platform dependent.
-//
-// The lock must be unlocked by the thread that locked it.
-// The lock is also not recursive (ie. cannot be taken multiple times).
-class Lock {
- public:
-  Lock();
-  ~Lock();
-
-  void Acquire();
-  void Release();
-
-  friend class AutoLock;
-
- private:
-  class Impl;
-  Impl* impl_;
-
-  CORE_DISALLOW_COPY_AND_ASSIGN(Lock);
-};
-
-// Manages the lock automatically. It will be locked when AutoLock
-// is constructed and release when AutoLock goes out of scope.
-class AutoLock {
- public:
-  explicit AutoLock(Lock& lock) : lock_(&lock) { lock_->Acquire(); }
-
-  explicit AutoLock(Lock* lock) : lock_(lock) { lock_->Acquire(); }
-
-  ~AutoLock() { lock_->Release(); }
-
- private:
-  Lock* lock_;
-
-  CORE_DISALLOW_COPY_AND_ASSIGN(AutoLock);
-};
-
-}  // namespace wvcdm
-
-#endif  // WVCDM_UTIL_LOCK_H_
diff --git a/util/include/log.h b/util/include/log.h
index ce390a0..d79ff00 100644
--- a/util/include/log.h
+++ b/util/include/log.h
@@ -14,11 +14,15 @@ namespace wvcdm {
 // Simple logging class. The implementation is platform dependent.
 
 typedef enum {
-  LOG_ERROR,
-  LOG_WARN,
-  LOG_INFO,
-  LOG_DEBUG,
-  LOG_VERBOSE
+  // This log level should only be used for |g_cutoff|, in order to silence all
+  // logging. It should never be passed to |Log()| as a log level.
+  LOG_SILENT = -1,
+
+  LOG_ERROR = 0,
+  LOG_WARN = 1,
+  LOG_INFO = 2,
+  LOG_DEBUG = 3,
+  LOG_VERBOSE = 4,
 } LogPriority;
 
 extern LogPriority g_cutoff;