diff --git a/packager/app/packager_main.cc b/packager/app/packager_main.cc
index 144efac5f6..e450e5d334 100644
--- a/packager/app/packager_main.cc
+++ b/packager/app/packager_main.cc
@@ -25,7 +25,7 @@
 #include "packager/base/time/clock.h"
 #include "packager/media/base/container_names.h"
 #include "packager/media/base/demuxer.h"
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/key_source.h"
 #include "packager/media/base/muxer_options.h"
 #include "packager/media/base/muxer_util.h"
@@ -105,15 +105,19 @@ std::string DetermineTextFileFormat(const std::string& file) {
   return "";
 }
 
-edash_packager::media::EncryptionMode GetEncryptionMode(
+edash_packager::media::FourCC GetProtectionScheme(
     const std::string& protection_scheme) {
   if (protection_scheme == "cenc") {
-    return edash_packager::media::kEncryptionModeAesCtr;
+    return edash_packager::media::FOURCC_cenc;
+  } else if (protection_scheme == "cens") {
+    return edash_packager::media::FOURCC_cens;
   } else if (protection_scheme == "cbc1") {
-    return edash_packager::media::kEncryptionModeAesCbc;
+    return edash_packager::media::FOURCC_cbc1;
+  } else if (protection_scheme == "cbcs") {
+    return edash_packager::media::FOURCC_cbcs;
   } else {
     LOG(ERROR) << "Unknown protection scheme: " << protection_scheme;
-    return edash_packager::media::kEncryptionModeUnknown;
+    return edash_packager::media::FOURCC_NULL;
   }
 }
 
@@ -310,7 +314,7 @@ bool CreateRemuxJobs(const StreamDescriptorList& stream_descriptors,
                           FLAGS_max_sd_pixels,
                           FLAGS_clear_lead,
                           FLAGS_crypto_period_duration,
-                          GetEncryptionMode(FLAGS_protection_scheme));
+                          GetProtectionScheme(FLAGS_protection_scheme));
     }
 
     scoped_ptr<MuxerListener> muxer_listener;
@@ -374,11 +378,11 @@ Status RunRemuxJobs(const std::vector<RemuxJob*>& remux_jobs) {
 }
 
 bool RunPackager(const StreamDescriptorList& stream_descriptors) {
-  EncryptionMode encryption_mode = GetEncryptionMode(FLAGS_protection_scheme);
-  if (encryption_mode == kEncryptionModeUnknown)
+  const FourCC protection_scheme = GetProtectionScheme(FLAGS_protection_scheme);
+  if (protection_scheme == FOURCC_NULL)
     return false;
-  if (encryption_mode == kEncryptionModeAesCbc && !FLAGS_iv.empty()) {
-    if (FLAGS_iv.size() != 16) {
+  if (protection_scheme == FOURCC_cbc1 || protection_scheme == FOURCC_cbcs) {
+    if (!FLAGS_iv.empty() && FLAGS_iv.size() != 16) {
       LOG(ERROR) << "Iv size should be 16 bytes for CBC encryption mode.";
       return false;
     }
diff --git a/packager/media/base/aes_cryptor.cc b/packager/media/base/aes_cryptor.cc
index e85914434f..dee1d3e909 100644
--- a/packager/media/base/aes_cryptor.cc
+++ b/packager/media/base/aes_cryptor.cc
@@ -7,6 +7,8 @@
 #include "packager/media/base/aes_cryptor.h"
 
 #include <openssl/aes.h>
+#include <openssl/err.h>
+#include <openssl/rand.h>
 
 #include "packager/base/logging.h"
 #include "packager/base/stl_util.h"
@@ -53,6 +55,25 @@ size_t AesCryptor::NumPaddingBytes(size_t size) const {
   return 0;
 }
 
+bool AesCryptor::GenerateRandomIv(FourCC protection_scheme,
+                                  std::vector<uint8_t>* iv) {
+  // ISO/IEC 23001-7:2016 10.1 and 10.3 For 'cenc' and 'cens'
+  // default_Per_Sample_IV_Size and Per_Sample_IV_Size SHOULD be 8-bytes.
+  // There is no official guideline on the iv size for 'cbc1' and 'cbcs',
+  // but 16-byte provides better security.
+  const size_t iv_size =
+      (protection_scheme == FOURCC_cenc || protection_scheme == FOURCC_cens)
+          ? 8
+          : 16;
+  iv->resize(iv_size);
+  if (RAND_bytes(iv->data(), iv_size) != 1) {
+    LOG(ERROR) << "RAND_bytes failed with error: "
+               << ERR_error_string(ERR_get_error(), NULL);
+    return false;
+  }
+  return true;
+}
+
 }  // namespace media
 }  // namespace edash_packager
 
diff --git a/packager/media/base/aes_cryptor.h b/packager/media/base/aes_cryptor.h
index 5e4dc0be52..c17fbd307f 100644
--- a/packager/media/base/aes_cryptor.h
+++ b/packager/media/base/aes_cryptor.h
@@ -12,6 +12,7 @@
 
 #include "packager/base/macros.h"
 #include "packager/base/memory/scoped_ptr.h"
+#include "packager/media/base/fourccs.h"
 
 struct aes_key_st;
 typedef struct aes_key_st AES_KEY;
@@ -58,6 +59,13 @@ class AesCryptor {
   /// @return The current iv.
   const std::vector<uint8_t>& iv() const { return iv_; }
 
+  /// @param protection_scheme specifies the protection scheme: 'cenc', 'cens',
+  ///        'cbc1', 'cbcs', which is useful to determine the random iv size.
+  /// @param iv points to generated initialization vector.
+  /// @return true on success, false otherwise.
+  static bool GenerateRandomIv(FourCC protection_scheme,
+                               std::vector<uint8_t>* iv);
+
  protected:
   void set_iv(const std::vector<uint8_t>& iv) { iv_ = iv; }
   const AES_KEY* aes_key() const { return aes_key_.get(); }
diff --git a/packager/media/base/aes_cryptor_unittest.cc b/packager/media/base/aes_cryptor_unittest.cc
index 8df13f9213..5328f3f9c7 100644
--- a/packager/media/base/aes_cryptor_unittest.cc
+++ b/packager/media/base/aes_cryptor_unittest.cc
@@ -220,12 +220,12 @@ TEST_F(AesCtrEncryptorTest, 128BitIVBoundaryCaseEncryption) {
   EXPECT_EQ(encrypted, encrypted_verify);
 }
 
-TEST_F(AesCtrEncryptorTest, InitWithRandomIv) {
-  const uint8_t kIvSize = 8;
-  ASSERT_TRUE(encryptor_.InitializeWithRandomIv(key_, kIvSize));
-  ASSERT_EQ(kIvSize, encryptor_.iv().size());
-  LOG(INFO) << "Random IV: "
-            << base::HexEncode(&encryptor_.iv()[0], encryptor_.iv().size());
+TEST_F(AesCtrEncryptorTest, GenerateRandomIv) {
+  const uint8_t kCencIvSize = 8;
+  std::vector<uint8_t> iv;
+  ASSERT_TRUE(AesCryptor::GenerateRandomIv(FOURCC_cenc, &iv));
+  ASSERT_EQ(kCencIvSize, iv.size());
+  LOG(INFO) << "Random IV: " << base::HexEncode(iv.data(), iv.size());
 }
 
 TEST_F(AesCtrEncryptorTest, UnsupportedKeySize) {
@@ -238,10 +238,6 @@ TEST_F(AesCtrEncryptorTest, UnsupportedIV) {
   ASSERT_FALSE(encryptor_.InitializeWithIv(key_, iv));
 }
 
-TEST_F(AesCtrEncryptorTest, IncorrectIvSize) {
-  ASSERT_FALSE(encryptor_.InitializeWithRandomIv(key_, 15));
-}
-
 class AesCtrEncryptorSubsampleTest
     : public AesCtrEncryptorTest,
       public ::testing::WithParamInterface<SubsampleTestCase> {};
diff --git a/packager/media/base/aes_encryptor.cc b/packager/media/base/aes_encryptor.cc
index 54ccf2e848..53b20f4bc4 100644
--- a/packager/media/base/aes_encryptor.cc
+++ b/packager/media/base/aes_encryptor.cc
@@ -7,8 +7,6 @@
 #include "packager/media/base/aes_encryptor.h"
 
 #include <openssl/aes.h>
-#include <openssl/err.h>
-#include <openssl/rand.h>
 
 #include "packager/base/logging.h"
 
@@ -40,17 +38,6 @@ namespace media {
 AesEncryptor::AesEncryptor() {}
 AesEncryptor::~AesEncryptor() {}
 
-bool AesEncryptor::InitializeWithRandomIv(const std::vector<uint8_t>& key,
-                                          uint8_t iv_size) {
-  std::vector<uint8_t> iv(iv_size, 0);
-  if (RAND_bytes(iv.data(), iv_size) != 1) {
-    LOG(ERROR) << "RAND_bytes failed with error: "
-               << ERR_error_string(ERR_get_error(), NULL);
-    return false;
-  }
-  return InitializeWithIv(key, iv);
-}
-
 bool AesEncryptor::InitializeWithIv(const std::vector<uint8_t>& key,
                                     const std::vector<uint8_t>& iv) {
   if (!IsKeySizeValidForAes(key.size())) {
diff --git a/packager/media/base/aes_encryptor.h b/packager/media/base/aes_encryptor.h
index 2d84ae9448..ceea48a4c0 100644
--- a/packager/media/base/aes_encryptor.h
+++ b/packager/media/base/aes_encryptor.h
@@ -24,11 +24,6 @@ class AesEncryptor : public AesCryptor {
   AesEncryptor();
   ~AesEncryptor() override;
 
-  /// Initialize the encryptor with specified key and a random generated IV
-  /// of the specified size.
-  /// @return true on successful initialization, false otherwise.
-  bool InitializeWithRandomIv(const std::vector<uint8_t>& key, uint8_t iv_size);
-
   /// Initialize the encryptor with specified key and IV.
   /// @return true on successful initialization, false otherwise.
   bool InitializeWithIv(const std::vector<uint8_t>& key,
diff --git a/packager/media/base/decrypt_config.cc b/packager/media/base/decrypt_config.cc
index d8c73946be..882d5ed5c2 100644
--- a/packager/media/base/decrypt_config.cc
+++ b/packager/media/base/decrypt_config.cc
@@ -9,14 +9,19 @@
 namespace edash_packager {
 namespace media {
 
+DecryptConfig::DecryptConfig(const std::vector<uint8_t>& key_id,
+                             const std::vector<uint8_t>& iv,
+                             const std::vector<SubsampleEntry>& subsamples)
+    : DecryptConfig(key_id, iv, subsamples, FOURCC_cenc) {}
+
 DecryptConfig::DecryptConfig(const std::vector<uint8_t>& key_id,
                              const std::vector<uint8_t>& iv,
                              const std::vector<SubsampleEntry>& subsamples,
-                             EncryptionMode decryption_mode)
+                             FourCC protection_scheme)
     : key_id_(key_id),
       iv_(iv),
       subsamples_(subsamples),
-      decryption_mode_(decryption_mode) {
+      protection_scheme_(protection_scheme) {
   CHECK_GT(key_id.size(), 0u);
 }
 
diff --git a/packager/media/base/decrypt_config.h b/packager/media/base/decrypt_config.h
index 82a86e34ef..73194d1afa 100644
--- a/packager/media/base/decrypt_config.h
+++ b/packager/media/base/decrypt_config.h
@@ -11,7 +11,7 @@
 #include <vector>
 
 #include "packager/base/memory/scoped_ptr.h"
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 
 namespace edash_packager {
 namespace media {
@@ -42,23 +42,35 @@ class DecryptConfig {
   /// Keys are always 128 bits.
   static const size_t kDecryptionKeySize = 16;
 
+  /// Create a 'cenc' decrypt config.
   /// @param key_id is the ID that references the decryption key.
   /// @param iv is the initialization vector defined by the encryptor.
   /// @param subsamples defines the clear and encrypted portions of the sample
   ///        as described in SubsampleEntry. A decrypted buffer will be equal
   ///        in size to the sum of the subsample sizes.
-  /// @param decryption_mode decryption_mode is to determine which decryptor to
-  /// use.
+  DecryptConfig(const std::vector<uint8_t>& key_id,
+                const std::vector<uint8_t>& iv,
+                const std::vector<SubsampleEntry>& subsamples);
+
+  /// Create a general decrypt config with possible pattern-based encryption.
+  /// @param key_id is the ID that references the decryption key.
+  /// @param iv is the initialization vector defined by the encryptor.
+  /// @param subsamples defines the clear and encrypted portions of the sample
+  ///        as described in SubsampleEntry. A decrypted buffer will be equal
+  ///        in size to the sum of the subsample sizes.
+  /// @param protection_scheme specifies the protection scheme: 'cenc', 'cens',
+  ///        'cbc1', 'cbcs'.
   DecryptConfig(const std::vector<uint8_t>& key_id,
                 const std::vector<uint8_t>& iv,
                 const std::vector<SubsampleEntry>& subsamples,
-                EncryptionMode decryption_mode);
+                FourCC protection_scheme);
+
   ~DecryptConfig();
 
   const std::vector<uint8_t>& key_id() const { return key_id_; }
   const std::vector<uint8_t>& iv() const { return iv_; }
   const std::vector<SubsampleEntry>& subsamples() const { return subsamples_; }
-  EncryptionMode decryption_mode() const { return decryption_mode_; }
+  FourCC protection_scheme() const { return protection_scheme_; }
 
  private:
   const std::vector<uint8_t> key_id_;
@@ -70,7 +82,7 @@ class DecryptConfig {
   // (less data ignored by data_offset_) is encrypted.
   const std::vector<SubsampleEntry> subsamples_;
 
-  EncryptionMode decryption_mode_;
+  const FourCC protection_scheme_;
 
   DISALLOW_COPY_AND_ASSIGN(DecryptConfig);
 };
diff --git a/packager/media/base/decryptor_source.cc b/packager/media/base/decryptor_source.cc
index 4375b87cc1..c23177545a 100644
--- a/packager/media/base/decryptor_source.cc
+++ b/packager/media/base/decryptor_source.cc
@@ -8,6 +8,7 @@
 
 #include "packager/base/logging.h"
 #include "packager/base/stl_util.h"
+#include "packager/media/base/aes_decryptor.h"
 
 namespace edash_packager {
 namespace media {
@@ -39,16 +40,16 @@ bool DecryptorSource::DecryptSampleBuffer(const DecryptConfig* decrypt_config,
     }
 
     scoped_ptr<AesCryptor> aes_decryptor;
-    switch (decrypt_config->decryption_mode()) {
-      case kEncryptionModeAesCtr:
+    switch (decrypt_config->protection_scheme()) {
+      case FOURCC_cenc:
         aes_decryptor.reset(new AesCtrDecryptor);
         break;
-      case kEncryptionModeAesCbc:
+      case FOURCC_cbc1:
         aes_decryptor.reset(new AesCbcDecryptor(kNoPadding, kChainAcrossCalls));
         break;
       default:
-        LOG(ERROR) << "Unsupported Decryption Mode: "
-                   << decrypt_config->decryption_mode();
+        LOG(ERROR) << "Unsupported protection scheme: "
+                   << decrypt_config->protection_scheme();
         return false;
     }
 
diff --git a/packager/media/base/decryptor_source_unittest.cc b/packager/media/base/decryptor_source_unittest.cc
index be1f99d959..a5fe29b627 100644
--- a/packager/media/base/decryptor_source_unittest.cc
+++ b/packager/media/base/decryptor_source_unittest.cc
@@ -81,10 +81,9 @@ TEST_F(DecryptorSourceTest, FullSampleDecryption) {
 
   DecryptConfig decrypt_config(key_id_,
                                std::vector<uint8_t>(kIv, kIv + arraysize(kIv)),
-                               std::vector<SubsampleEntry>(),
-                               kEncryptionModeAesCtr);
-  ASSERT_TRUE(decryptor_source_.DecryptSampleBuffer(&decrypt_config, &buffer_[0],
-                                                    buffer_.size()));
+                               std::vector<SubsampleEntry>());
+  ASSERT_TRUE(decryptor_source_.DecryptSampleBuffer(
+      &decrypt_config, &buffer_[0], buffer_.size()));
   EXPECT_EQ(std::vector<uint8_t>(
                 kExpectedDecryptedBuffer,
                 kExpectedDecryptedBuffer + arraysize(kExpectedDecryptedBuffer)),
@@ -95,7 +94,7 @@ TEST_F(DecryptorSourceTest, FullSampleDecryption) {
   buffer_.assign(kBuffer2, kBuffer2 + arraysize(kBuffer2));
   DecryptConfig decrypt_config2(
       key_id_, std::vector<uint8_t>(kIv2, kIv2 + arraysize(kIv2)),
-      std::vector<SubsampleEntry>(), kEncryptionModeAesCtr);
+      std::vector<SubsampleEntry>());
   ASSERT_TRUE(decryptor_source_.DecryptSampleBuffer(
       &decrypt_config2, &buffer_[0], buffer_.size()));
   EXPECT_EQ(std::vector<uint8_t>(kExpectedDecryptedBuffer2,
@@ -130,8 +129,7 @@ TEST_F(DecryptorSourceTest, SubsampleDecryption) {
   DecryptConfig decrypt_config(
       key_id_, std::vector<uint8_t>(kIv, kIv + arraysize(kIv)),
       std::vector<SubsampleEntry>(kSubsamples,
-                                  kSubsamples + arraysize(kSubsamples)),
-      kEncryptionModeAesCtr);
+                                  kSubsamples + arraysize(kSubsamples)));
   ASSERT_TRUE(decryptor_source_.DecryptSampleBuffer(
       &decrypt_config, &buffer_[0], buffer_.size()));
   EXPECT_EQ(std::vector<uint8_t>(
@@ -155,8 +153,7 @@ TEST_F(DecryptorSourceTest, SubsampleDecryptionSizeValidation) {
   DecryptConfig decrypt_config(
       key_id_, std::vector<uint8_t>(kIv, kIv + arraysize(kIv)),
       std::vector<SubsampleEntry>(kSubsamples,
-                                  kSubsamples + arraysize(kSubsamples)),
-      kEncryptionModeAesCtr);
+                                  kSubsamples + arraysize(kSubsamples)));
   ASSERT_FALSE(decryptor_source_.DecryptSampleBuffer(
       &decrypt_config, &buffer_[0], buffer_.size()));
 }
@@ -167,8 +164,7 @@ TEST_F(DecryptorSourceTest, DecryptFailedIfGetKeyFailed) {
 
   DecryptConfig decrypt_config(key_id_,
                                std::vector<uint8_t>(kIv, kIv + arraysize(kIv)),
-                               std::vector<SubsampleEntry>(),
-                               kEncryptionModeAesCtr);
+                               std::vector<SubsampleEntry>());
   ASSERT_FALSE(decryptor_source_.DecryptSampleBuffer(
       &decrypt_config, &buffer_[0], buffer_.size()));
 }
diff --git a/packager/media/base/encryption_modes.h b/packager/media/base/encryption_modes.h
deleted file mode 100644
index c99c344b6f..0000000000
--- a/packager/media/base/encryption_modes.h
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright 2016 Google Inc. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-#ifndef MEDIA_BASE_ENCRYPTION_MODE_H_
-#define MEDIA_BASE_ENCRYPTION_MODE_H_
-
-namespace edash_packager {
-namespace media {
-
-/// Supported encryption mode.
-enum EncryptionMode {
-  kEncryptionModeUnknown,
-  kEncryptionModeAesCtr,
-  kEncryptionModeAesCbc
-};
-
-}  // namespace media
-}  // namespace edash_packager
-
-#endif  // MEDIA_BASE_ENCRYPTION_MODE_H_
diff --git a/packager/media/base/fourccs.h b/packager/media/base/fourccs.h
index 2253b6f3f1..fd0e6f9c55 100644
--- a/packager/media/base/fourccs.h
+++ b/packager/media/base/fourccs.h
@@ -21,7 +21,9 @@ enum FourCC {
   FOURCC_avcC = 0x61766343,
   FOURCC_bloc = 0x626C6F63,
   FOURCC_cbc1 = 0x63626331,
+  FOURCC_cbcs = 0x63626373,
   FOURCC_cenc = 0x63656e63,
+  FOURCC_cens = 0x63656e73,
   FOURCC_co64 = 0x636f3634,
   FOURCC_ctim = 0x6374696d,
   FOURCC_ctts = 0x63747473,
diff --git a/packager/media/base/muxer.cc b/packager/media/base/muxer.cc
index ba921cd19e..e765f7e143 100644
--- a/packager/media/base/muxer.cc
+++ b/packager/media/base/muxer.cc
@@ -6,6 +6,7 @@
 
 #include "packager/media/base/muxer.h"
 
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/media_sample.h"
 #include "packager/media/base/media_stream.h"
 
@@ -19,7 +20,7 @@ Muxer::Muxer(const MuxerOptions& options)
       max_sd_pixels_(0),
       clear_lead_in_seconds_(0),
       crypto_period_duration_in_seconds_(0),
-      encryption_mode_(kEncryptionModeUnknown),
+      protection_scheme_(FOURCC_NULL),
       cancelled_(false),
       clock_(NULL) {}
 
@@ -29,13 +30,13 @@ void Muxer::SetKeySource(KeySource* encryption_key_source,
                          uint32_t max_sd_pixels,
                          double clear_lead_in_seconds,
                          double crypto_period_duration_in_seconds,
-                         EncryptionMode encryption_mode) {
+                         FourCC protection_scheme) {
   DCHECK(encryption_key_source);
   encryption_key_source_ = encryption_key_source;
   max_sd_pixels_ = max_sd_pixels;
   clear_lead_in_seconds_ = clear_lead_in_seconds;
   crypto_period_duration_in_seconds_ = crypto_period_duration_in_seconds;
-  encryption_mode_ = encryption_mode;
+  protection_scheme_ = protection_scheme;
 }
 
 void Muxer::AddStream(MediaStream* stream) {
diff --git a/packager/media/base/muxer.h b/packager/media/base/muxer.h
index 234c87eea4..9f34201260 100644
--- a/packager/media/base/muxer.h
+++ b/packager/media/base/muxer.h
@@ -14,7 +14,7 @@
 #include "packager/base/memory/ref_counted.h"
 #include "packager/base/memory/scoped_ptr.h"
 #include "packager/base/time/clock.h"
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/muxer_options.h"
 #include "packager/media/base/status.h"
 #include "packager/media/event/muxer_listener.h"
@@ -45,11 +45,13 @@ class Muxer {
   /// @param crypto_period_duration_in_seconds specifies crypto period duration
   ///        in seconds. A positive value means key rotation is enabled, the
   ///        key source must support key rotation in this case.
+  /// @param protection_scheme specifies the protection scheme: 'cenc', 'cens',
+  ///        'cbc1', 'cbcs'.
   void SetKeySource(KeySource* encryption_key_source,
                     uint32_t max_sd_pixels,
                     double clear_lead_in_seconds,
                     double crypto_period_duration_in_seconds,
-                    EncryptionMode encryption_mode);
+                    FourCC protection_scheme);
 
   /// Add video/audio stream.
   void AddStream(MediaStream* stream);
@@ -94,7 +96,7 @@ class Muxer {
   MuxerListener* muxer_listener() { return muxer_listener_.get(); }
   ProgressListener* progress_listener() { return progress_listener_.get(); }
   base::Clock* clock() { return clock_; }
-  EncryptionMode encryption_mode() const { return encryption_mode_; }
+  FourCC protection_scheme() const { return protection_scheme_; }
 
  private:
   friend class MediaStream;  // Needed to access AddSample.
@@ -120,7 +122,7 @@ class Muxer {
   uint32_t max_sd_pixels_;
   double clear_lead_in_seconds_;
   double crypto_period_duration_in_seconds_;
-  EncryptionMode encryption_mode_;
+  FourCC protection_scheme_;
   bool cancelled_;
 
   scoped_ptr<MuxerListener> muxer_listener_;
diff --git a/packager/media/formats/mp4/encrypting_fragmenter.cc b/packager/media/formats/mp4/encrypting_fragmenter.cc
index 6fe21f9ad9..7de34f9f04 100644
--- a/packager/media/formats/mp4/encrypting_fragmenter.cc
+++ b/packager/media/formats/mp4/encrypting_fragmenter.cc
@@ -22,9 +22,6 @@ namespace media {
 namespace mp4 {
 
 namespace {
-// Generate 64bit IV by default.
-const size_t kDefaultIvSizeForCtr = 8u;
-const size_t kDefaultIvSizeForCbc = 16u;
 const size_t kCencBlockSize = 16u;
 
 // Adds one or more subsamples to |*subsamples|.  This may add more than one
@@ -66,14 +63,14 @@ EncryptingFragmenter::EncryptingFragmenter(
     TrackFragment* traf,
     scoped_ptr<EncryptionKey> encryption_key,
     int64_t clear_time,
-    EncryptionMode encryption_mode)
+    FourCC protection_scheme)
     : Fragmenter(traf),
       info_(info),
       encryption_key_(encryption_key.Pass()),
       nalu_length_size_(GetNaluLengthSize(*info)),
       video_codec_(GetVideoCodec(*info)),
       clear_time_(clear_time),
-      encryption_mode_(encryption_mode) {
+      protection_scheme_(protection_scheme) {
   DCHECK(encryption_key_);
   if (video_codec_ == kCodecVP8) {
     vpx_parser_.reset(new VP8Parser);
@@ -175,22 +172,21 @@ void EncryptingFragmenter::FinalizeFragmentForEncryption() {
 
 Status EncryptingFragmenter::CreateEncryptor() {
   DCHECK(encryption_key_);
-  scoped_ptr<AesEncryptor> encryptor;
-  size_t default_iv_size = 0;
-  if (encryption_mode_ == kEncryptionModeAesCtr) {
-    encryptor.reset(new AesCtrEncryptor);
-    default_iv_size = kDefaultIvSizeForCtr;
-  } else if (encryption_mode_ == kEncryptionModeAesCbc) {
-    encryptor.reset(new AesCbcEncryptor(kNoPadding, kChainAcrossCalls));
-    default_iv_size = kDefaultIvSizeForCbc;
-  } else {
-    return Status(error::MUXER_FAILURE, "Unsupported encryption mode.");
+  scoped_ptr<AesCryptor> encryptor;
+  switch (protection_scheme_) {
+    case FOURCC_cenc:
+      encryptor.reset(new AesCtrEncryptor);
+      break;
+    case FOURCC_cbc1:
+      encryptor.reset(new AesCbcEncryptor(kNoPadding, kChainAcrossCalls));
+      break;
+    default:
+      return Status(error::MUXER_FAILURE, "Unsupported protection scheme.");
   }
-  const bool initialized = encryption_key_->iv.empty()
-                               ? encryptor->InitializeWithRandomIv(
-                                     encryption_key_->key, default_iv_size)
-                               : encryptor->InitializeWithIv(
-                                     encryption_key_->key, encryption_key_->iv);
+
+  DCHECK(!encryption_key_->iv.empty());
+  const bool initialized =
+      encryptor->InitializeWithIv(encryption_key_->key, encryption_key_->iv);
   if (!initialized)
     return Status(error::MUXER_FAILURE, "Failed to create the encryptor.");
   encryptor_ = encryptor.Pass();
@@ -229,7 +225,7 @@ Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
         // within the superframe.
         // For AES-CBC mode 'cbc1' scheme, clear data is sized appropriately so
         // that the cipher data is block aligned.
-        if (is_superframe || encryption_mode_ == kEncryptionModeAesCbc) {
+        if (is_superframe || protection_scheme_ == FOURCC_cbc1) {
           const uint16_t misalign_bytes =
               subsample.cipher_bytes % kCencBlockSize;
           subsample.clear_bytes += misalign_bytes;
@@ -271,7 +267,7 @@ Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
 
           // For AES-CBC mode 'cbc1' scheme, clear data is sized appropriately
           // so that the cipher data is block aligned.
-          if (encryption_mode_ == kEncryptionModeAesCbc) {
+          if (protection_scheme_ == FOURCC_cbc1) {
             const uint16_t misalign_bytes = cipher_bytes % kCencBlockSize;
             current_clear_bytes += misalign_bytes;
             cipher_bytes -= misalign_bytes;
@@ -303,7 +299,7 @@ Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
     uint64_t encryption_data_size = sample->data_size();
     // AES-CBC mode requires all encrypted cipher blocks to be 16 bytes. The
     // partial blocks are left unencrypted.
-    if (encryption_mode_ == kEncryptionModeAesCbc)
+    if (protection_scheme_ == FOURCC_cbc1)
       encryption_data_size -= encryption_data_size % kCencBlockSize;
     EncryptBytes(data, encryption_data_size);
   }
diff --git a/packager/media/formats/mp4/encrypting_fragmenter.h b/packager/media/formats/mp4/encrypting_fragmenter.h
index bb2cc22a05..e960d5bd52 100644
--- a/packager/media/formats/mp4/encrypting_fragmenter.h
+++ b/packager/media/formats/mp4/encrypting_fragmenter.h
@@ -9,7 +9,7 @@
 
 #include "packager/base/memory/ref_counted.h"
 #include "packager/base/memory/scoped_ptr.h"
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/filters/vpx_parser.h"
 #include "packager/media/formats/mp4/fragmenter.h"
 #include "packager/media/formats/mp4/video_slice_header_parser.h"
@@ -17,7 +17,7 @@
 namespace edash_packager {
 namespace media {
 
-class AesEncryptor;
+class AesCryptor;
 class StreamInfo;
 struct EncryptionKey;
 
@@ -30,11 +30,13 @@ class EncryptingFragmenter : public Fragmenter {
   /// @param encryption_key contains the encryption parameters.
   /// @param clear_time specifies clear lead duration in units of the current
   ///        track's timescale.
+  /// @param protection_scheme specifies the protection scheme: 'cenc', 'cens',
+  ///        'cbc1', 'cbcs'.
   EncryptingFragmenter(scoped_refptr<StreamInfo> info,
                        TrackFragment* traf,
                        scoped_ptr<EncryptionKey> encryption_key,
                        int64_t clear_time,
-                       EncryptionMode encryption_mode);
+                       FourCC protection_scheme);
 
   ~EncryptingFragmenter() override;
 
@@ -57,8 +59,9 @@ class EncryptingFragmenter : public Fragmenter {
   /// @return OK on success, an error status otherwise.
   Status CreateEncryptor();
 
-  EncryptionKey* encryption_key() { return encryption_key_.get(); }
-  AesEncryptor* encryptor() { return encryptor_.get(); }
+  const EncryptionKey* encryption_key() const { return encryption_key_.get(); }
+  AesCryptor* encryptor() { return encryptor_.get(); }
+  FourCC protection_scheme() const { return protection_scheme_; }
 
   void set_encryption_key(scoped_ptr<EncryptionKey> encryption_key) {
     encryption_key_ = encryption_key.Pass();
@@ -73,14 +76,14 @@ class EncryptingFragmenter : public Fragmenter {
 
   scoped_refptr<StreamInfo> info_;
   scoped_ptr<EncryptionKey> encryption_key_;
-  scoped_ptr<AesEncryptor> encryptor_;
+  scoped_ptr<AesCryptor> encryptor_;
   // If this stream contains AVC, subsample encryption specifies that the size
   // and type of NAL units remain unencrypted. This function returns the size of
   // the size field in bytes. Can be 1, 2 or 4 bytes.
   const uint8_t nalu_length_size_;
   const VideoCodec video_codec_;
   int64_t clear_time_;
-  EncryptionMode encryption_mode_;
+  FourCC protection_scheme_;
 
   scoped_ptr<VPxParser> vpx_parser_;
   scoped_ptr<VideoSliceHeaderParser> header_parser_;
diff --git a/packager/media/formats/mp4/key_rotation_fragmenter.cc b/packager/media/formats/mp4/key_rotation_fragmenter.cc
index 14c7f6c551..2d25d677f3 100644
--- a/packager/media/formats/mp4/key_rotation_fragmenter.cc
+++ b/packager/media/formats/mp4/key_rotation_fragmenter.cc
@@ -24,13 +24,13 @@ KeyRotationFragmenter::KeyRotationFragmenter(MovieFragment* moof,
                                              KeySource::TrackType track_type,
                                              int64_t crypto_period_duration,
                                              int64_t clear_time,
-                                             MuxerListener* muxer_listener,
-                                             EncryptionMode encryption_mode)
+                                             FourCC protection_scheme,
+                                             MuxerListener* muxer_listener)
     : EncryptingFragmenter(info,
                            traf,
                            scoped_ptr<EncryptionKey>(new EncryptionKey()),
                            clear_time,
-                           encryption_mode),
+                           protection_scheme),
       moof_(moof),
       encryption_key_source_(encryption_key_source),
       track_type_(track_type),
@@ -55,6 +55,12 @@ Status KeyRotationFragmenter::PrepareFragmentForEncryption(
         current_crypto_period_index, track_type_, encryption_key.get());
     if (!status.ok())
       return status;
+    if (encryption_key->iv.empty()) {
+      if (!AesCryptor::GenerateRandomIv(protection_scheme(),
+                                        &encryption_key->iv)) {
+        return Status(error::INTERNAL_ERROR, "Failed to generate random iv.");
+      }
+    }
     set_encryption_key(encryption_key.Pass());
     prev_crypto_period_index_ = current_crypto_period_index;
     need_to_refresh_encryptor = true;
diff --git a/packager/media/formats/mp4/key_rotation_fragmenter.h b/packager/media/formats/mp4/key_rotation_fragmenter.h
index f798aaa0fd..821d140d4f 100644
--- a/packager/media/formats/mp4/key_rotation_fragmenter.h
+++ b/packager/media/formats/mp4/key_rotation_fragmenter.h
@@ -7,7 +7,7 @@
 #ifndef MEDIA_FORMATS_MP4_KEY_ROTATION_FRAGMENTER_H_
 #define MEDIA_FORMATS_MP4_KEY_ROTATION_FRAGMENTER_H_
 
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/key_source.h"
 #include "packager/media/event/muxer_listener.h"
 #include "packager/media/formats/mp4/encrypting_fragmenter.h"
@@ -32,6 +32,8 @@ class KeyRotationFragmenter : public EncryptingFragmenter {
   ///        of the current track's timescale.
   /// @param clear_time specifies clear lead duration in units of the current
   ///        track's timescale.
+  /// @param protection_scheme specifies the protection scheme: 'cenc', 'cens',
+  ///        'cbc1', 'cbcs'.
   /// @param muxer_listener is a pointer to MuxerListener for notifying
   ///        muxer related events. This may be null.
   KeyRotationFragmenter(MovieFragment* moof,
@@ -41,8 +43,8 @@ class KeyRotationFragmenter : public EncryptingFragmenter {
                         KeySource::TrackType track_type,
                         int64_t crypto_period_duration,
                         int64_t clear_time,
-                        MuxerListener* muxer_listener,
-                        EncryptionMode encryption_mode);
+                        FourCC protection_scheme,
+                        MuxerListener* muxer_listener);
   ~KeyRotationFragmenter() override;
 
  protected:
diff --git a/packager/media/formats/mp4/mp4_muxer.cc b/packager/media/formats/mp4/mp4_muxer.cc
index 445f02d2e6..723884e2f7 100644
--- a/packager/media/formats/mp4/mp4_muxer.cc
+++ b/packager/media/formats/mp4/mp4_muxer.cc
@@ -147,15 +147,10 @@ Status MP4Muxer::Initialize() {
         new MultiSegmentSegmenter(options(), ftyp.Pass(), moov.Pass()));
   }
 
-  Status segmenter_initialized =
-      segmenter_->Initialize(streams(),
-                             muxer_listener(),
-                             progress_listener(),
-                             encryption_key_source(),
-                             max_sd_pixels(),
-                             clear_lead_in_seconds(),
-                             crypto_period_duration_in_seconds(),
-                             encryption_mode());
+  const Status segmenter_initialized = segmenter_->Initialize(
+      streams(), muxer_listener(), progress_listener(), encryption_key_source(),
+      max_sd_pixels(), clear_lead_in_seconds(),
+      crypto_period_duration_in_seconds(), protection_scheme());
 
   if (!segmenter_initialized.ok())
     return segmenter_initialized;
diff --git a/packager/media/formats/mp4/segmenter.cc b/packager/media/formats/mp4/segmenter.cc
index 55572955aa..761801b206 100644
--- a/packager/media/formats/mp4/segmenter.cc
+++ b/packager/media/formats/mp4/segmenter.cc
@@ -9,6 +9,7 @@
 #include <algorithm>
 
 #include "packager/base/stl_util.h"
+#include "packager/media/base/aes_cryptor.h"
 #include "packager/media/base/buffer_writer.h"
 #include "packager/media/base/key_source.h"
 #include "packager/media/base/media_sample.h"
@@ -26,8 +27,6 @@ namespace mp4 {
 
 namespace {
 
-// Generate 64bit IV by default.
-const size_t kDefaultIvSize = 8u;
 const size_t kCencKeyIdSize = 16u;
 
 // The version of cenc implemented here. CENC 4.
@@ -50,26 +49,24 @@ uint64_t Rescale(uint64_t time_in_old_scale,
 
 void GenerateSinf(const EncryptionKey& encryption_key,
                   FourCC old_type,
-                  EncryptionMode encryption_mode,
+                  FourCC protection_scheme,
                   ProtectionSchemeInfo* sinf) {
   sinf->format.format = old_type;
 
-  if (encryption_mode == kEncryptionModeAesCtr){
-    sinf->type.type = FOURCC_cenc;
-  } else if (encryption_mode == kEncryptionModeAesCbc) {
-    sinf->type.type = FOURCC_cbc1;
-  }
-
+  DCHECK_NE(protection_scheme, FOURCC_NULL);
+  sinf->type.type = protection_scheme;
   sinf->type.version = kCencSchemeVersion;
-  sinf->info.track_encryption.is_encrypted = true;
-  sinf->info.track_encryption.default_iv_size =
-      encryption_key.iv.empty() ? kDefaultIvSize : encryption_key.iv.size();
-  sinf->info.track_encryption.default_kid = encryption_key.key_id;
+
+  auto& track_encryption = sinf->info.track_encryption;
+  track_encryption.is_encrypted = true;
+  DCHECK(!encryption_key.iv.empty());
+  track_encryption.default_iv_size = encryption_key.iv.size();
+  track_encryption.default_kid = encryption_key.key_id;
 }
 
 void GenerateEncryptedSampleEntry(const EncryptionKey& encryption_key,
                                   double clear_lead_in_seconds,
-                                  EncryptionMode encryption_mode,
+                                  FourCC protection_scheme,
                                   SampleDescription* description) {
   DCHECK(description);
   if (description->type == kVideo) {
@@ -81,7 +78,7 @@ void GenerateEncryptedSampleEntry(const EncryptionKey& encryption_key,
 
     // Convert the first entry to an encrypted entry.
     VideoSampleEntry& entry = description->video_entries[0];
-    GenerateSinf(encryption_key, entry.format, encryption_mode, &entry.sinf);
+    GenerateSinf(encryption_key, entry.format, protection_scheme, &entry.sinf);
     entry.format = FOURCC_encv;
   } else {
     DCHECK_EQ(kAudio, description->type);
@@ -93,7 +90,7 @@ void GenerateEncryptedSampleEntry(const EncryptionKey& encryption_key,
 
     // Convert the first entry to an encrypted entry.
     AudioSampleEntry& entry = description->audio_entries[0];
-    GenerateSinf(encryption_key, entry.format, encryption_mode, &entry.sinf);
+    GenerateSinf(encryption_key, entry.format, protection_scheme, &entry.sinf);
     entry.format = FOURCC_enca;
   }
 }
@@ -137,7 +134,7 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
                              uint32_t max_sd_pixels,
                              double clear_lead_in_seconds,
                              double crypto_period_duration_in_seconds,
-                             EncryptionMode encryption_mode) {
+                             FourCC protection_scheme) {
   DCHECK_LT(0u, streams.size());
   muxer_listener_ = muxer_listener;
   progress_listener_ = progress_listener;
@@ -173,8 +170,10 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
       encryption_key.key_id.assign(
           kKeyRotationDefaultKeyId,
           kKeyRotationDefaultKeyId + arraysize(kKeyRotationDefaultKeyId));
+      if (!AesCryptor::GenerateRandomIv(protection_scheme, &encryption_key.iv))
+        return Status(error::INTERNAL_ERROR, "Failed to generate random iv.");
       GenerateEncryptedSampleEntry(encryption_key, clear_lead_in_seconds,
-                                   encryption_mode, &description);
+                                   protection_scheme, &description);
       if (muxer_listener_) {
         muxer_listener_->OnEncryptionInfoReady(
             kInitialEncryptionInfo, encryption_key.key_id,
@@ -186,7 +185,7 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
           encryption_key_source, track_type,
           crypto_period_duration_in_seconds * streams[i]->info()->time_scale(),
           clear_lead_in_seconds * streams[i]->info()->time_scale(),
-          muxer_listener_, encryption_mode);
+          protection_scheme, muxer_listener_);
       continue;
     }
 
@@ -195,9 +194,13 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
         encryption_key_source->GetKey(track_type, encryption_key.get());
     if (!status.ok())
       return status;
+    if (encryption_key->iv.empty()) {
+      if (!AesCryptor::GenerateRandomIv(protection_scheme, &encryption_key->iv))
+        return Status(error::INTERNAL_ERROR, "Failed to generate random iv.");
+    }
 
     GenerateEncryptedSampleEntry(*encryption_key, clear_lead_in_seconds,
-                                 encryption_mode, &description);
+                                 protection_scheme, &description);
 
     if (moov_->pssh.empty()) {
       moov_->pssh.resize(encryption_key->key_system_info.size());
@@ -215,7 +218,7 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
     fragmenters_[i] = new EncryptingFragmenter(
         streams[i]->info(), &moof_->tracks[i], encryption_key.Pass(),
         clear_lead_in_seconds * streams[i]->info()->time_scale(),
-        encryption_mode);
+        protection_scheme);
   }
 
   // Choose the first stream if there is no VIDEO.
diff --git a/packager/media/formats/mp4/segmenter.h b/packager/media/formats/mp4/segmenter.h
index b0972839eb..8adda270ce 100644
--- a/packager/media/formats/mp4/segmenter.h
+++ b/packager/media/formats/mp4/segmenter.h
@@ -12,7 +12,7 @@
 
 #include "packager/base/memory/ref_counted.h"
 #include "packager/base/memory/scoped_ptr.h"
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/status.h"
 #include "packager/media/formats/mp4/box_definitions.h"
 
@@ -59,6 +59,8 @@ class Segmenter {
   ///        pixels per frame than max_sd_pixels, it is HD, SD otherwise.
   /// @param clear_time specifies clear lead duration in seconds.
   /// @param crypto_period_duration specifies crypto period duration in seconds.
+  /// @param protection_scheme specifies the protection scheme: 'senc', 'sens',
+  ///        'cbc1', 'cbcs'.
   /// @return OK on success, an error status otherwise.
   Status Initialize(const std::vector<MediaStream*>& streams,
                     MuxerListener* muxer_listener,
@@ -67,7 +69,7 @@ class Segmenter {
                     uint32_t max_sd_pixels,
                     double clear_lead_in_seconds,
                     double crypto_period_duration_in_seconds,
-                    EncryptionMode encryption_mode);
+                    FourCC protection_scheme);
 
   /// Finalize the segmenter.
   /// @return OK on success, an error status otherwise.
diff --git a/packager/media/formats/mp4/track_run_iterator.cc b/packager/media/formats/mp4/track_run_iterator.cc
index 1ee3916e12..240d8b7b60 100644
--- a/packager/media/formats/mp4/track_run_iterator.cc
+++ b/packager/media/formats/mp4/track_run_iterator.cc
@@ -8,7 +8,7 @@
 #include <limits>
 
 #include "packager/media/base/buffer_reader.h"
-#include "packager/media/base/encryption_modes.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/rcheck.h"
 #include "packager/media/formats/mp4/chunk_info_iterator.h"
 #include "packager/media/formats/mp4/composition_offset_iterator.h"
@@ -600,24 +600,10 @@ scoped_ptr<DecryptConfig> TrackRunIterator::GetDecryptConfig() {
 
   FourCC protection_scheme = is_audio() ? audio_description().sinf.type.type
                                         : video_description().sinf.type.type;
-  EncryptionMode decryption_mode;
-  switch (protection_scheme) {
-    case FOURCC_cenc:
-      decryption_mode = kEncryptionModeAesCtr;
-      break;
-    case FOURCC_cbc1:
-      decryption_mode = kEncryptionModeAesCbc;
-      break;
-    default:
-      LOG(ERROR) << "Unsupported protection scheme.";
-      return scoped_ptr<DecryptConfig>();
-  }
-
-  return scoped_ptr<DecryptConfig>(new DecryptConfig(
-      track_encryption().default_kid,
-      sample_encryption_entry.initialization_vector,
-      sample_encryption_entry.subsamples,
-      decryption_mode));
+  return scoped_ptr<DecryptConfig>(
+      new DecryptConfig(track_encryption().default_kid,
+                        sample_encryption_entry.initialization_vector,
+                        sample_encryption_entry.subsamples, protection_scheme));
 }
 
 }  // namespace mp4
diff --git a/packager/media/formats/webm/encryptor.cc b/packager/media/formats/webm/encryptor.cc
index 1fcecbc443..d029fc0dfd 100644
--- a/packager/media/formats/webm/encryptor.cc
+++ b/packager/media/formats/webm/encryptor.cc
@@ -7,6 +7,7 @@
 #include "packager/media/formats/webm/encryptor.h"
 
 #include "packager/media/base/aes_encryptor.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/media_sample.h"
 
 namespace edash_packager {
@@ -14,9 +15,6 @@ namespace media {
 namespace webm {
 namespace {
 
-// Generate 64bit IV by default.
-const size_t kDefaultIvSize = 8u;
-
 Status CreateContentEncryption(mkvmuxer::Track* track, EncryptionKey* key) {
   if (!track->AddContentEncoding()) {
     return Status(error::INTERNAL_ERROR,
@@ -107,13 +105,14 @@ Status Encryptor::CreateEncryptor(MuxerListener* muxer_listener,
   Status status = key_source->GetKey(track_type, encryption_key.get());
   if (!status.ok())
     return status;
+  if (encryption_key->iv.empty()) {
+    if (!AesCryptor::GenerateRandomIv(FOURCC_cenc, &encryption_key->iv))
+      return Status(error::INTERNAL_ERROR, "Failed to generate random iv.");
+  }
 
   scoped_ptr<AesCtrEncryptor> encryptor(new AesCtrEncryptor());
-  const bool initialized = encryption_key->iv.empty()
-                               ? encryptor->InitializeWithRandomIv(
-                                     encryption_key->key, kDefaultIvSize)
-                               : encryptor->InitializeWithIv(
-                                     encryption_key->key, encryption_key->iv);
+  const bool initialized =
+      encryptor->InitializeWithIv(encryption_key->key, encryption_key->iv);
   if (!initialized)
     return Status(error::INTERNAL_ERROR, "Failed to create the encryptor.");
 
diff --git a/packager/media/formats/webm/webm_crypto_helpers.cc b/packager/media/formats/webm/webm_crypto_helpers.cc
index e350f7bc5c..338d13c087 100644
--- a/packager/media/formats/webm/webm_crypto_helpers.cc
+++ b/packager/media/formats/webm/webm_crypto_helpers.cc
@@ -6,7 +6,6 @@
 
 #include "packager/base/logging.h"
 #include "packager/base/sys_byteorder.h"
-#include "packager/media/base/encryption_modes.h"
 #include "packager/media/formats/webm/webm_constants.h"
 
 namespace edash_packager {
@@ -56,8 +55,7 @@ bool WebMCreateDecryptConfig(const uint8_t* data,
   decrypt_config->reset(new DecryptConfig(
       std::vector<uint8_t>(key_id, key_id + key_id_size),
       std::vector<uint8_t>(counter_block.begin(), counter_block.end()),
-      std::vector<SubsampleEntry>(),
-      kEncryptionModeAesCtr));
+      std::vector<SubsampleEntry>()));
   *data_offset = frame_offset;
 
   return true;
diff --git a/packager/media/formats/webm/webm_muxer.cc b/packager/media/formats/webm/webm_muxer.cc
index af342f6ddd..9091af3a91 100644
--- a/packager/media/formats/webm/webm_muxer.cc
+++ b/packager/media/formats/webm/webm_muxer.cc
@@ -6,6 +6,7 @@
 
 #include "packager/media/formats/webm/webm_muxer.h"
 
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/media_sample.h"
 #include "packager/media/base/media_stream.h"
 #include "packager/media/base/stream_info.h"
@@ -30,12 +31,11 @@ Status WebMMuxer::Initialize() {
                   "Key rotation is not implemented for WebM");
   }
 
-  if (encryption_key_source() && (encryption_mode() != kEncryptionModeAesCtr)) {
+  if (encryption_key_source() && (protection_scheme() != FOURCC_cenc)) {
     NOTIMPLEMENTED()
-        << "WebM muxer does not support encryption mode other than AES-CTR.";
-    return Status(
-        error::UNIMPLEMENTED,
-        "WebM muxer does not support encryption mode other than AES-CTR.");
+        << "WebM does not support protection scheme other than 'cenc'.";
+    return Status(error::UNIMPLEMENTED,
+                  "WebM does not support protection scheme other than 'cenc'.");
   }
 
   scoped_ptr<MkvWriter> writer(new MkvWriter);
diff --git a/packager/media/test/packager_test.cc b/packager/media/test/packager_test.cc
index 7b84182660..8db096ccc5 100644
--- a/packager/media/test/packager_test.cc
+++ b/packager/media/test/packager_test.cc
@@ -11,8 +11,8 @@
 #include "packager/base/strings/stringprintf.h"
 #include "packager/base/time/clock.h"
 #include "packager/media/base/demuxer.h"
-#include "packager/media/base/encryption_modes.h"
 #include "packager/media/base/fixed_key_source.h"
+#include "packager/media/base/fourccs.h"
 #include "packager/media/base/media_stream.h"
 #include "packager/media/base/muxer.h"
 #include "packager/media/base/stream_info.h"
@@ -174,10 +174,8 @@ void PackagerTestBasic::Remux(const std::string& input,
 
     if (enable_encryption) {
       muxer_video->SetKeySource(encryption_key_source.get(),
-                                KeySource::TRACK_TYPE_SD,
-                                kClearLeadInSeconds,
-                                kCryptoDurationInSeconds,
-                                kEncryptionModeAesCtr);
+                                KeySource::TRACK_TYPE_SD, kClearLeadInSeconds,
+                                kCryptoDurationInSeconds, FOURCC_cenc);
     }
   }
 
@@ -196,10 +194,8 @@ void PackagerTestBasic::Remux(const std::string& input,
 
     if (enable_encryption) {
       muxer_audio->SetKeySource(encryption_key_source.get(),
-                                KeySource::TRACK_TYPE_SD,
-                                kClearLeadInSeconds,
-                                kCryptoDurationInSeconds,
-                                kEncryptionModeAesCtr);
+                                KeySource::TRACK_TYPE_SD, kClearLeadInSeconds,
+                                kCryptoDurationInSeconds, FOURCC_cenc);
     }
   }