Refactor and optimize cbc encryption/decryption

- Optimize and clean up encryption and decryption code.
- Consolidate various CBC encryption/decryption schemes into a
  common class.
- Make it a constructor argument whether cipher block chain is
  continuous across Encrypt/Decrypt calls.
- Also align protected region size as required in CENC spec.

Issue #77

Change-Id: I533d92ada3cd80933b532b9c3a1cca105ba66f8e

packager/app/packager_main.cc

@@ -112,7 +112,7 @@ edash_packager::media::EncryptionMode GetEncryptionMode(
   } else if (protection_scheme == "cbc1") {
     return edash_packager::media::kEncryptionModeAesCbc;
   } else {
-    LOG(ERROR) << "Protection scheme is unknown.";
+    LOG(ERROR) << "Unknown protection scheme: " << protection_scheme;
     return edash_packager::media::kEncryptionModeUnknown;
   }
 }
@@ -377,6 +377,12 @@ bool RunPackager(const StreamDescriptorList& stream_descriptors) {
   EncryptionMode encryption_mode = GetEncryptionMode(FLAGS_protection_scheme);
   if (encryption_mode == kEncryptionModeUnknown)
     return false;
+  if (encryption_mode == kEncryptionModeAesCbc && !FLAGS_iv.empty()) {
+    if (FLAGS_iv.size() != 16) {
+      LOG(ERROR) << "Iv size should be 16 bytes for CBC encryption mode.";
+      return false;
+    }
+  }
 
   if (!AssignFlagsFromProfile())
     return false;

packager/media/base/aes_decryptor.cc

@@ -27,6 +27,32 @@ namespace media {
 AesDecryptor::AesDecryptor() {}
 AesDecryptor::~AesDecryptor() {}
 
+bool AesDecryptor::Decrypt(const std::vector<uint8_t>& ciphertext,
+                           std::vector<uint8_t>* plaintext) {
+  DCHECK(plaintext);
+  plaintext->resize(ciphertext.size());
+  size_t plaintext_size;
+  if (!DecryptInternal(ciphertext.data(), ciphertext.size(), plaintext->data(),
+                       &plaintext_size))
+    return false;
+  plaintext->resize(plaintext_size);
+  return true;
+}
+
+bool AesDecryptor::Decrypt(const std::string& ciphertext,
+                           std::string* plaintext) {
+  DCHECK(plaintext);
+  plaintext->resize(ciphertext.size());
+  size_t plaintext_size;
+  if (!DecryptInternal(reinterpret_cast<const uint8_t*>(ciphertext.data()),
+                       ciphertext.size(),
+                       reinterpret_cast<uint8_t*>(string_as_array(plaintext)),
+                       &plaintext_size))
+    return false;
+  plaintext->resize(plaintext_size);
+  return true;
+}
+
 AesCtrDecryptor::AesCtrDecryptor() {}
 
 AesCtrDecryptor::~AesCtrDecryptor() {}
@@ -37,163 +63,119 @@ bool AesCtrDecryptor::InitializeWithIv(const std::vector<uint8_t>& key,
   return encryptor_->InitializeWithIv(key, iv);
 }
 
-// For AES CTR, encryption and decryption are identical.
-bool AesCtrDecryptor::Decrypt(const uint8_t* ciphertext,
-                              size_t ciphertext_size,
-                              uint8_t* plaintext) {
-  DCHECK(encryptor_);
-  return encryptor_->EncryptData(ciphertext, ciphertext_size, plaintext);
-}
-
-bool AesCtrDecryptor::Decrypt(const std::vector<uint8_t>& ciphertext,
-                              std::vector<uint8_t>* plaintext) {
-  DCHECK(encryptor_);
-  return encryptor_->Encrypt(ciphertext, plaintext);
-}
-
-bool AesCtrDecryptor::Decrypt(const std::string& ciphertext,
-                              std::string* plaintext) {
-  DCHECK(encryptor_);
-  return encryptor_->Encrypt(ciphertext, plaintext);
-}
-
 bool AesCtrDecryptor::SetIv(const std::vector<uint8_t>& iv) {
   DCHECK(encryptor_);
   return encryptor_->SetIv(iv);
 }
 
-AesCbcPkcs5Decryptor::AesCbcPkcs5Decryptor() {}
+bool AesCtrDecryptor::DecryptInternal(const uint8_t* ciphertext,
-AesCbcPkcs5Decryptor::~AesCbcPkcs5Decryptor() {}
+                                      size_t ciphertext_size,
+                                      uint8_t* plaintext,
+                                      size_t* plaintext_size) {
+  DCHECK(encryptor_);
+  *plaintext_size = ciphertext_size;
+  // For AES CTR, encryption and decryption are identical.
+  return encryptor_->Encrypt(ciphertext, ciphertext_size, plaintext);
+}
 
-bool AesCbcPkcs5Decryptor::InitializeWithIv(const std::vector<uint8_t>& key,
+AesCbcDecryptor::AesCbcDecryptor(CbcPaddingScheme padding_scheme,
+                                 bool chain_across_calls)
+    : padding_scheme_(padding_scheme),
+      chain_across_calls_(chain_across_calls) {
+  if (padding_scheme_ != kNoPadding) {
+    CHECK(!chain_across_calls) << "cipher block chain across calls only makes "
+                                  "sense if the padding_scheme is kNoPadding.";
+  }
+}
+AesCbcDecryptor::~AesCbcDecryptor() {}
+
+bool AesCbcDecryptor::InitializeWithIv(const std::vector<uint8_t>& key,
                                        const std::vector<uint8_t>& iv) {
   if (!IsKeySizeValidForAes(key.size())) {
     LOG(ERROR) << "Invalid AES key size: " << key.size();
     return false;
   }
+
+  aes_key_.reset(new AES_KEY());
+  CHECK_EQ(AES_set_decrypt_key(key.data(), key.size() * 8, aes_key_.get()), 0);
+
+  return SetIv(iv);
+}
+
+bool AesCbcDecryptor::SetIv(const std::vector<uint8_t>& iv) {
   if (iv.size() != AES_BLOCK_SIZE) {
     LOG(ERROR) << "Invalid IV size: " << iv.size();
     return false;
   }
 
-  aes_key_.reset(new AES_KEY());
-  CHECK_EQ(AES_set_decrypt_key(&key[0], key.size() * 8, aes_key_.get()), 0);
-
   iv_ = iv;
   return true;
 }
 
-bool AesCbcPkcs5Decryptor::Decrypt(const uint8_t* ciphertext,
+bool AesCbcDecryptor::DecryptInternal(const uint8_t* ciphertext,
                                       size_t ciphertext_size,
-                                   uint8_t* plaintext) {
+                                      uint8_t* plaintext,
-  NOTIMPLEMENTED();
+                                      size_t* plaintext_size) {
-  return false;
+  DCHECK(plaintext_size);
-}
+  DCHECK(aes_key_);
-
+  // Plaintext size is the same as ciphertext size except for pkcs5 padding.
-bool AesCbcPkcs5Decryptor::Decrypt(const std::vector<uint8_t>& ciphertext,
+  // Will update later if using pkcs5 padding.
-                                   std::vector<uint8_t>* plaintext) {
+  *plaintext_size = ciphertext_size;
-  NOTIMPLEMENTED();
+  if (ciphertext_size == 0) {
-  return false;
+    if (padding_scheme_ == kPkcs5Padding) {
-}
+      LOG(ERROR) << "Expected ciphertext to be at least " << AES_BLOCK_SIZE
-
+                 << " bytes with Pkcs5 padding";
-bool AesCbcPkcs5Decryptor::Decrypt(const std::string& ciphertext,
-                                   std::string* plaintext) {
-  if ((ciphertext.size() % AES_BLOCK_SIZE) != 0) {
-    LOG(ERROR) << "Expecting cipher text size to be multiple of "
-               << AES_BLOCK_SIZE << ", got " << ciphertext.size();
       return false;
     }
-
+    return true;
+  }
   DCHECK(plaintext);
-  DCHECK(aes_key_);
 
-  plaintext->resize(ciphertext.size());
+  std::vector<uint8_t> local_iv(iv_);
-  AES_cbc_encrypt(reinterpret_cast<const uint8_t*>(ciphertext.data()),
+  const size_t residual_block_size = ciphertext_size % AES_BLOCK_SIZE;
-                  reinterpret_cast<uint8_t*>(string_as_array(plaintext)),
+  if (residual_block_size == 0) {
-                  ciphertext.size(),
+    AES_cbc_encrypt(ciphertext, plaintext, ciphertext_size, aes_key_.get(),
-                  aes_key_.get(),
+                    local_iv.data(), AES_DECRYPT);
-                  &iv_[0],
+    if (chain_across_calls_)
-                  AES_DECRYPT);
+      iv_ = local_iv;
+    if (padding_scheme_ != kPkcs5Padding)
+      return true;
 
     // Strip off PKCS5 padding bytes.
-  const uint8_t num_padding_bytes = (*plaintext)[plaintext->size() - 1];
+    const uint8_t num_padding_bytes = plaintext[ciphertext_size - 1];
     if (num_padding_bytes > AES_BLOCK_SIZE) {
       LOG(ERROR) << "Padding length is too large : "
                  << static_cast<int>(num_padding_bytes);
       return false;
     }
-  plaintext->resize(plaintext->size() - num_padding_bytes);
+    *plaintext_size -= num_padding_bytes;
     return true;
-}
+  } else if (padding_scheme_ != kCtsPadding) {
-
+    LOG(ERROR) << "Expecting cipher text size to be multiple of "
-bool AesCbcPkcs5Decryptor::SetIv(const std::vector<uint8_t>& iv) {
+               << AES_BLOCK_SIZE << ", got " << ciphertext_size;
-  if (iv.size() != AES_BLOCK_SIZE) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
     return false;
   }
 
-  iv_ = iv;
+  DCHECK(!chain_across_calls_);
-  return true;
+  DCHECK_EQ(padding_scheme_, kCtsPadding);
-}
-
-AesCbcCtsDecryptor::AesCbcCtsDecryptor() {}
-AesCbcCtsDecryptor::~AesCbcCtsDecryptor() {}
-
-bool AesCbcCtsDecryptor::InitializeWithIv(const std::vector<uint8_t>& key,
-                                          const std::vector<uint8_t>& iv) {
-  if (!IsKeySizeValidForAes(key.size())) {
-    LOG(ERROR) << "Invalid AES key size: " << key.size();
-    return false;
-  }
-  if (iv.size() != AES_BLOCK_SIZE) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
-    return false;
-  }
-
-  aes_key_.reset(new AES_KEY());
-  CHECK_EQ(AES_set_decrypt_key(&key[0], key.size() * 8, aes_key_.get()), 0);
-
-  iv_ = iv;
-  return true;
-}
-
-bool AesCbcCtsDecryptor::Decrypt(const uint8_t* ciphertext,
-                                 size_t ciphertext_size,
-                                 uint8_t* plaintext) {
-  DCHECK(ciphertext);
-  DCHECK(plaintext);
-
   if (ciphertext_size < AES_BLOCK_SIZE) {
     // Don't have a full block, leave unencrypted.
     memcpy(plaintext, ciphertext, ciphertext_size);
     return true;
   }
 
-  std::vector<uint8_t> iv(iv_);
-  size_t residual_block_size = ciphertext_size % AES_BLOCK_SIZE;
-
-  if (residual_block_size == 0) {
-    // No residual block. No need to do ciphertext stealing.
-    AES_cbc_encrypt(ciphertext,
-                    plaintext,
-                    ciphertext_size,
-                    aes_key_.get(),
-                    &iv[0],
-                    AES_DECRYPT);
-    return true;
-  }
-
   // AES-CBC decrypt everything up to the next-to-last full block.
-  size_t cbc_size = ciphertext_size - residual_block_size;
+  const size_t cbc_size = ciphertext_size - residual_block_size;
   if (cbc_size > AES_BLOCK_SIZE) {
-    AES_cbc_encrypt(ciphertext,
+    AES_cbc_encrypt(ciphertext, plaintext, cbc_size - AES_BLOCK_SIZE,
-                    plaintext,
+                    aes_key_.get(), local_iv.data(), AES_DECRYPT);
-                    cbc_size - AES_BLOCK_SIZE,
-                    aes_key_.get(),
-                    &iv[0],
-                    AES_DECRYPT);
   }
 
+  const uint8_t* next_to_last_ciphertext_block =
+      ciphertext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE;
+  uint8_t* next_to_last_plaintext_block =
+      plaintext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE;
+
   // Determine what the last IV should be so that we can "skip ahead" in the
   // CBC decryption.
   std::vector<uint8_t> last_iv(
@@ -203,64 +185,24 @@ bool AesCbcCtsDecryptor::Decrypt(const uint8_t* ciphertext,
 
   // Decrypt the next-to-last block using the IV determined above. This decrypts
   // the residual block bits.
-  AES_cbc_encrypt(
+  AES_cbc_encrypt(next_to_last_ciphertext_block, next_to_last_plaintext_block,
-      ciphertext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE,
+                  AES_BLOCK_SIZE, aes_key_.get(), last_iv.data(), AES_DECRYPT);
-      plaintext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE,
-      AES_BLOCK_SIZE, aes_key_.get(), &last_iv[0], AES_DECRYPT);
 
-  // Swap back the residual block bits and the next-to-last full block.
+  // Swap back the residual block bits and the next-to-last block.
   if (plaintext == ciphertext) {
-    uint8_t* ptr1 = plaintext + ciphertext_size - residual_block_size;
+    std::swap_ranges(next_to_last_plaintext_block,
-    uint8_t* ptr2 = plaintext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE;
+                     next_to_last_plaintext_block + residual_block_size,
-    for (size_t i = 0; i < residual_block_size; ++i) {
+                     next_to_last_plaintext_block + AES_BLOCK_SIZE);
-      uint8_t temp = *ptr1;
-      *ptr1 = *ptr2;
-      *ptr2 = temp;
-      ++ptr1;
-      ++ptr2;
-    }
   } else {
-    uint8_t* residual_plaintext_block =
+    memcpy(next_to_last_plaintext_block + AES_BLOCK_SIZE,
-        plaintext + ciphertext_size - residual_block_size;
+           next_to_last_plaintext_block, residual_block_size);
-    memcpy(residual_plaintext_block, residual_plaintext_block - AES_BLOCK_SIZE,
+    memcpy(next_to_last_plaintext_block,
-           residual_block_size);
+           next_to_last_ciphertext_block + AES_BLOCK_SIZE, residual_block_size);
-    memcpy(residual_plaintext_block - AES_BLOCK_SIZE,
-           ciphertext + ciphertext_size - residual_block_size,
-           residual_block_size);
   }
 
-  // Decrypt the last full block.
+  // Decrypt the next-to-last full block.
-  AES_cbc_encrypt(
+  AES_cbc_encrypt(next_to_last_plaintext_block, next_to_last_plaintext_block,
-      plaintext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE,
+                  AES_BLOCK_SIZE, aes_key_.get(), local_iv.data(), AES_DECRYPT);
-      plaintext + ciphertext_size - residual_block_size - AES_BLOCK_SIZE,
-      AES_BLOCK_SIZE, aes_key_.get(), &iv[0], AES_DECRYPT);
-  return true;
-}
-
-bool AesCbcCtsDecryptor::Decrypt(const std::vector<uint8_t>& ciphertext,
-                                 std::vector<uint8_t>* plaintext) {
-  DCHECK(plaintext);
-
-  plaintext->resize(ciphertext.size(), 0);
-  if (ciphertext.empty())
-    return true;
-
-  return Decrypt(ciphertext.data(), ciphertext.size(), &(*plaintext)[0]);
-}
-
-bool AesCbcCtsDecryptor::Decrypt(const std::string& ciphertext,
-                                 std::string* plaintext) {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-bool AesCbcCtsDecryptor::SetIv(const std::vector<uint8_t>& iv) {
-  if (iv.size() != AES_BLOCK_SIZE) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
-    return false;
-  }
-
-  iv_ = iv;
   return true;
 }
 

packager/media/base/aes_decryptor.h

@@ -27,34 +27,42 @@ class AesDecryptor {
   AesDecryptor();
   virtual ~AesDecryptor();
 
+  /// Initialize the decryptor with specified key and IV.
+  /// @return true on successful initialization, false otherwise.
   virtual bool InitializeWithIv(const std::vector<uint8_t>& key,
                                 const std::vector<uint8_t>& iv) = 0;
 
   /// @name Various forms of decrypt calls.
   /// The plaintext and ciphertext pointers can be the same address.
   /// @{
-  virtual bool Decrypt(const uint8_t* ciphertext,
+  bool Decrypt(const std::vector<uint8_t>& ciphertext,
+               std::vector<uint8_t>* plaintext);
+  bool Decrypt(const std::string& ciphertext, std::string* plaintext);
+  bool Decrypt(const uint8_t* ciphertext,
                size_t ciphertext_size,
-                       uint8_t* plaintext) = 0;
+               uint8_t* plaintext) {
-
+    size_t plaintext_size;
-  virtual bool Decrypt(const std::vector<uint8_t>& ciphertext,
+    return DecryptInternal(ciphertext, ciphertext_size, plaintext,
-                       std::vector<uint8_t>* plaintext) = 0;
+                           &plaintext_size);
-
+  }
-  virtual bool Decrypt(const std::string& ciphertext,
-                       std::string* plaintext) = 0;
   /// @}
 
-  /// Set IV. @a block_offset_ is reset to 0 on success.
+  /// Set IV.
   /// @return true if successful, false if the input is invalid.
   virtual bool SetIv(const std::vector<uint8_t>& iv) = 0;
 
-  const std::vector<uint8_t>& iv() const { return iv_; }
-
  protected:
-  // Initialization vector, with size 8 or 16.
+  /// Internal implementation of decrypt function.
-  std::vector<uint8_t> iv_;
+  /// @param ciphertext points to the input ciphertext.
-  // Openssl AES_KEY.
+  /// @param ciphertext_size is the input ciphertext size.
-  scoped_ptr<AES_KEY> aes_key_;
+  /// @param[out] plaintext points to the output plaintext. @a plaintext and
+  ///             @a ciphertext can point to the same address.
+  /// @param[out] plaintext_size contains the size of plaintext on success.
+  ///             It should never be larger than @a ciphertext_size.
+  virtual bool DecryptInternal(const uint8_t* ciphertext,
+                               size_t ciphertext_size,
+                               uint8_t* plaintext,
+                               size_t* plaintext_size) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AesDecryptor);
@@ -71,80 +79,57 @@ class AesCtrDecryptor : public AesDecryptor {
   bool InitializeWithIv(const std::vector<uint8_t>& key,
                         const std::vector<uint8_t>& iv) override;
 
-  bool Decrypt(const uint8_t* ciphertext,
-               size_t ciphertext_size,
-               uint8_t* plaintext) override;
-
-  bool Decrypt(const std::vector<uint8_t>& ciphertext,
-               std::vector<uint8_t>* plaintext) override;
-
-  bool Decrypt(const std::string& ciphertext, std::string* plaintext) override;
-
   bool SetIv(const std::vector<uint8_t>& iv) override;
   /// @}
 
   uint32_t block_offset() const { return encryptor_->block_offset(); }
 
+ protected:
+  bool DecryptInternal(const uint8_t* ciphertext,
+                       size_t ciphertext_size,
+                       uint8_t* plaintext,
+                       size_t* plaintext_size) override;
+
  private:
   scoped_ptr<AesCtrEncryptor> encryptor_;
 
   DISALLOW_COPY_AND_ASSIGN(AesCtrDecryptor);
 };
 
-// Class which implements AES-CBC (Cipher block chaining) decryption with
+// Class which implements AES-CBC (Cipher block chaining) decryption.
-// PKCS#5 padding.
+class AesCbcDecryptor : public AesDecryptor {
-class AesCbcPkcs5Decryptor : public AesDecryptor {
  public:
-  AesCbcPkcs5Decryptor();
+  /// @param padding_scheme indicates the padding scheme used. Currently
-  ~AesCbcPkcs5Decryptor() override;
+  ///        supported schemes: kNoPadding, kPkcs5Padding, kCtsPadding.
+  /// @param chain_across_calls indicates whether there is a continuous cipher
+  ///        block chain across calls for Decrypt function. If it is false, iv
+  ///        is not updated across Decrypt function calls.
+  AesCbcDecryptor(CbcPaddingScheme padding_scheme, bool chain_across_calls);
+  ~AesCbcDecryptor() override;
 
   /// @name AesDecryptor implementation overrides.
   /// @{
   bool InitializeWithIv(const std::vector<uint8_t>& key,
                         const std::vector<uint8_t>& iv) override;
 
-  bool Decrypt(const uint8_t* ciphertext,
-               size_t ciphertext_size,
-               uint8_t* plaintext) override;
-
-  bool Decrypt(const std::vector<uint8_t>& ciphertext,
-               std::vector<uint8_t>* plaintext) override;
-
-  bool Decrypt(const std::string& ciphertext, std::string* plaintext) override;
-
   bool SetIv(const std::vector<uint8_t>& iv) override;
   /// @}
 
- private:
+ protected:
-  DISALLOW_COPY_AND_ASSIGN(AesCbcPkcs5Decryptor);
+  bool DecryptInternal(const uint8_t* ciphertext,
-};
-
-// Class which implements AES-CBC (Cipher block chaining) decryption with
-// Ciphertext stealing.
-class AesCbcCtsDecryptor : public AesDecryptor {
- public:
-  AesCbcCtsDecryptor();
-  ~AesCbcCtsDecryptor() override;
-
-  /// @name AesDecryptor implementation overrides.
-  /// @{
-  bool InitializeWithIv(const std::vector<uint8_t>& key,
-                        const std::vector<uint8_t>& iv) override;
-
-  bool Decrypt(const uint8_t* ciphertext,
                        size_t ciphertext_size,
-               uint8_t* plaintext) override;
+                       uint8_t* plaintext,
-
+                       size_t* plaintext_size) override;
-  bool Decrypt(const std::vector<uint8_t>& ciphertext,
-               std::vector<uint8_t>* plaintext) override;
-
-  bool Decrypt(const std::string& ciphertext, std::string* plaintext) override;
-
-  bool SetIv(const std::vector<uint8_t>& iv) override;
-  /// @}
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(AesCbcCtsDecryptor);
+  // Openssl AES_KEY.
+  scoped_ptr<AES_KEY> aes_key_;
+  // Initialization vector, must be 16 for CBC.
+  std::vector<uint8_t> iv_;
+  const CbcPaddingScheme padding_scheme_;
+  const bool chain_across_calls_;
+
+  DISALLOW_COPY_AND_ASSIGN(AesCbcDecryptor);
 };
 
 }  // namespace media

packager/media/base/aes_encryptor.cc

@@ -32,9 +32,6 @@ bool IsKeySizeValidForAes(size_t key_size) {
   return key_size == 16 || key_size == 24 || key_size == 32;
 }
 
-// CENC protection scheme uses 128-bit keys in counter mode.
-const uint32_t kCencKeySize = 16;
-
 }  // namespace
 
 namespace edash_packager {
@@ -47,7 +44,7 @@ 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[0], iv_size) != 1) {
+  if (RAND_bytes(iv.data(), iv_size) != 1) {
     LOG(ERROR) << "RAND_bytes failed with error: "
                << ERR_error_string(ERR_get_error(), NULL);
     return false;
@@ -55,62 +52,98 @@ bool AesEncryptor::InitializeWithRandomIv(
   return InitializeWithIv(key, iv);
 }
 
+bool AesEncryptor::InitializeWithIv(const std::vector<uint8_t>& key,
+                                    const std::vector<uint8_t>& iv) {
+  if (!IsKeySizeValidForAes(key.size())) {
+    LOG(ERROR) << "Invalid AES key size: " << key.size();
+    return false;
+  }
+
+  aes_key_.reset(new AES_KEY());
+  CHECK_EQ(AES_set_encrypt_key(key.data(), key.size() * 8, aes_key_.get()), 0);
+  return SetIv(iv);
+}
+
 bool AesEncryptor::Encrypt(const std::vector<uint8_t>& plaintext,
                            std::vector<uint8_t>* ciphertext) {
-  if (plaintext.empty())
+  // Save plaintext size to make it work for in-place conversion, since the
-    return true;
+  // next statement will update the plaintext size.
-  ciphertext->resize(plaintext.size() + NumPaddingBytes(plaintext.size()));
+  const size_t plaintext_size = plaintext.size();
-  return EncryptData(plaintext.data(), plaintext.size(), ciphertext->data());
+  ciphertext->resize(plaintext_size + NumPaddingBytes(plaintext.size()));
+  return EncryptInternal(plaintext.data(), plaintext_size, ciphertext->data());
 }
 
 bool AesEncryptor::Encrypt(const std::string& plaintext,
                            std::string* ciphertext) {
-  ciphertext->resize(plaintext.size() + NumPaddingBytes(plaintext.size()));
+  // Save plaintext size to make it work for in-place conversion, since the
-  return EncryptData(reinterpret_cast<const uint8_t*>(plaintext.data()),
+  // next statement will update the plaintext size.
-                     plaintext.size(),
+  const size_t plaintext_size = plaintext.size();
+  ciphertext->resize(plaintext_size + NumPaddingBytes(plaintext.size()));
+  return EncryptInternal(
+      reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext_size,
       reinterpret_cast<uint8_t*>(string_as_array(ciphertext)));
 }
 
 AesCtrEncryptor::AesCtrEncryptor()
     : block_offset_(0),
       encrypted_counter_(AES_BLOCK_SIZE, 0),
-      counter_overflow_(false) {
+      counter_overflow_(false) {}
-  COMPILE_ASSERT(AES_BLOCK_SIZE == kCencKeySize,
-                 cenc_key_size_should_be_the_same_as_aes_block_size);
-}
 
 AesCtrEncryptor::~AesCtrEncryptor() {}
 
-bool AesCtrEncryptor::InitializeWithIv(const std::vector<uint8_t>& key,
+void AesCtrEncryptor::UpdateIv() {
-                                       const std::vector<uint8_t>& iv) {
+  block_offset_ = 0;
-  if (key.size() != kCencKeySize) {
+
-    LOG(ERROR) << "Invalid key size of " << key.size() << " for CENC.";
+  // As recommended in ISO/IEC FDIS 23001-7: CENC spec, for 64-bit (8-byte)
-    return false;
+  // IV_Sizes, initialization vectors for subsequent samples can be created by
+  // incrementing the initialization vector of the previous sample.
+  // For 128-bit (16-byte) IV_Sizes, initialization vectors for subsequent
+  // samples should be created by adding the block count of the previous sample
+  // to the initialization vector of the previous sample.
+  if (iv().size() == 8) {
+    counter_ = iv();
+    Increment64(&counter_[0]);
+    set_iv(counter_);
+    counter_.resize(AES_BLOCK_SIZE, 0);
+  } else {
+    DCHECK_EQ(16u, iv().size());
+    // Even though the block counter portion of the counter (bytes 8 to 15) is
+    // treated as a 64-bit number, it is recommended that the initialization
+    // vector is treated as a 128-bit number when calculating the next
+    // initialization vector from the previous one. The block counter portion
+    // is already incremented by number of blocks, the other 64 bits of the
+    // counter (bytes 0 to 7) is incremented here if the block counter portion
+    // has overflowed.
+    if (counter_overflow_)
+      Increment64(&counter_[0]);
+    set_iv(counter_);
   }
+  counter_overflow_ = false;
+}
+
+bool AesCtrEncryptor::SetIv(const std::vector<uint8_t>& iv) {
   if (!IsIvSizeValid(iv.size())) {
     LOG(ERROR) << "Invalid IV size: " << iv.size();
     return false;
   }
 
-  aes_key_.reset(new AES_KEY());
+  block_offset_ = 0;
-  CHECK_EQ(AES_set_encrypt_key(&key[0], AES_BLOCK_SIZE * 8, aes_key_.get()), 0);
+  set_iv(iv);
-  return SetIv(iv);
+  counter_ = iv;
+  counter_.resize(AES_BLOCK_SIZE, 0);
+  return true;
 }
 
-size_t AesCtrEncryptor::NumPaddingBytes(size_t size) {
+bool AesCtrEncryptor::EncryptInternal(const uint8_t* plaintext,
-  return 0;
-}
-
-bool AesCtrEncryptor::EncryptData(const uint8_t* plaintext,
                                       size_t plaintext_size,
                                       uint8_t* ciphertext) {
   DCHECK(plaintext);
   DCHECK(ciphertext);
-  DCHECK(aes_key_);
+  DCHECK(aes_key());
 
   for (size_t i = 0; i < plaintext_size; ++i) {
     if (block_offset_ == 0) {
-      AES_encrypt(&counter_[0], &encrypted_counter_[0], aes_key_.get());
+      AES_encrypt(&counter_[0], &encrypted_counter_[0], aes_key());
       // As mentioned in ISO/IEC FDIS 23001-7: CENC spec, of the 16 byte counter
       // block, bytes 8 to 15 (i.e. the least significant bytes) are used as a
       // simple 64 bit unsigned integer that is incremented by one for each
@@ -125,195 +158,111 @@ bool AesCtrEncryptor::EncryptData(const uint8_t* plaintext,
   return true;
 }
 
-void AesCtrEncryptor::UpdateIv() {
+size_t AesCtrEncryptor::NumPaddingBytes(size_t size) const {
-  block_offset_ = 0;
+  // No padding needed for CTR.
-
-  // As recommended in ISO/IEC FDIS 23001-7: CENC spec, for 64-bit (8-byte)
-  // IV_Sizes, initialization vectors for subsequent samples can be created by
-  // incrementing the initialization vector of the previous sample.
-  // For 128-bit (16-byte) IV_Sizes, initialization vectors for subsequent
-  // samples should be created by adding the block count of the previous sample
-  // to the initialization vector of the previous sample.
-  if (iv_.size() == 8) {
-    Increment64(&iv_[0]);
-    counter_ = iv_;
-    counter_.resize(AES_BLOCK_SIZE, 0);
-  } else {
-    DCHECK_EQ(16u, iv_.size());
-    // Even though the block counter portion of the counter (bytes 8 to 15) is
-    // treated as a 64-bit number, it is recommended that the initialization
-    // vector is treated as a 128-bit number when calculating the next
-    // initialization vector from the previous one. The block counter portion
-    // is already incremented by number of blocks, the other 64 bits of the
-    // counter (bytes 0 to 7) is incremented here if the block counter portion
-    // has overflowed.
-    if (counter_overflow_)
-      Increment64(&counter_[0]);
-    iv_ = counter_;
-  }
-  counter_overflow_ = false;
-}
-
-bool AesCtrEncryptor::SetIv(const std::vector<uint8_t>& iv) {
-  if (!IsIvSizeValid(iv.size())) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
-    return false;
-  }
-
-  block_offset_ = 0;
-  counter_ = iv_ = iv;
-  counter_.resize(AES_BLOCK_SIZE, 0);
-  return true;
-}
-
-AesCbcPkcs5Encryptor::AesCbcPkcs5Encryptor() {}
-AesCbcPkcs5Encryptor::~AesCbcPkcs5Encryptor() {}
-
-bool AesCbcPkcs5Encryptor::InitializeWithIv(const std::vector<uint8_t>& key,
-                                            const std::vector<uint8_t>& iv) {
-  if (!IsKeySizeValidForAes(key.size())) {
-    LOG(ERROR) << "Invalid AES key size: " << key.size();
-    return false;
-  }
-  if (iv.size() != AES_BLOCK_SIZE) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
-    return false;
-  }
-
-  aes_key_.reset(new AES_KEY());
-  CHECK_EQ(AES_set_encrypt_key(&key[0], key.size() * 8, aes_key_.get()), 0);
-
-  iv_ = iv;
-  return true;
-}
-
-size_t AesCbcPkcs5Encryptor::NumPaddingBytes(size_t size) {
-  return AES_BLOCK_SIZE - (size % AES_BLOCK_SIZE);
-}
-
-bool AesCbcPkcs5Encryptor::EncryptData(const uint8_t* plaintext,
-                                       size_t plaintext_size,
-                                       uint8_t* ciphertext) {
-  DCHECK(ciphertext);
-  DCHECK(aes_key_);
-
-  // Pad the input with PKCS5 padding.
-  // TODO(kqyang): Consider more efficient implementation.
-  memcpy(ciphertext, plaintext, plaintext_size);
-  for (size_t i = plaintext_size;
-       i < plaintext_size + NumPaddingBytes(plaintext_size); ++i) {
-    ciphertext[i] = NumPaddingBytes(plaintext_size);
-  }
-
-  std::vector<uint8_t> iv(iv_);
-  AES_cbc_encrypt(ciphertext, ciphertext,
-                  plaintext_size + NumPaddingBytes(plaintext_size),
-                  aes_key_.get(), &iv[0], AES_ENCRYPT);
-  return true;
-}
-
-void AesCbcPkcs5Encryptor::UpdateIv() {}
-
-bool AesCbcPkcs5Encryptor::SetIv(const std::vector<uint8_t>& iv) {
-  if (iv.size() != AES_BLOCK_SIZE) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
-    return false;
-  }
-
-  iv_ = iv;
-  return true;
-}
-
-AesCbcCtsEncryptor::AesCbcCtsEncryptor() {}
-AesCbcCtsEncryptor::~AesCbcCtsEncryptor() {}
-
-bool AesCbcCtsEncryptor::InitializeWithIv(const std::vector<uint8_t>& key,
-                                          const std::vector<uint8_t>& iv) {
-  if (!IsKeySizeValidForAes(key.size())) {
-    LOG(ERROR) << "Invalid AES key size: " << key.size();
-    return false;
-  }
-  if (iv.size() != AES_BLOCK_SIZE) {
-    LOG(ERROR) << "Invalid IV size: " << iv.size();
-    return false;
-  }
-
-  aes_key_.reset(new AES_KEY());
-  CHECK_EQ(AES_set_encrypt_key(&key[0], key.size() * 8, aes_key_.get()), 0);
-
-  iv_ = iv;
-  return true;
-}
-
-size_t AesCbcCtsEncryptor::NumPaddingBytes(size_t size) {
   return 0;
 }
 
-bool AesCbcCtsEncryptor::EncryptData(const uint8_t* plaintext,
+AesCbcEncryptor::AesCbcEncryptor(CbcPaddingScheme padding_scheme,
-                                     size_t size,
+                                 bool chain_across_calls)
-                                     uint8_t* ciphertext) {
+    : padding_scheme_(padding_scheme),
-  DCHECK(plaintext);
+      chain_across_calls_(chain_across_calls) {
-  DCHECK(ciphertext);
+  if (padding_scheme_ != kNoPadding) {
-
+    CHECK(!chain_across_calls) << "cipher block chain across calls only makes "
-  if (size < AES_BLOCK_SIZE) {
+                                  "sense if the padding_scheme is kNoPadding.";
-    // Don't have a full block, leave unencrypted.
-    memcpy(ciphertext, plaintext, size);
-    return true;
   }
+}
+AesCbcEncryptor::~AesCbcEncryptor() {}
 
-  std::vector<uint8_t> iv(iv_);
+void AesCbcEncryptor::UpdateIv() {
-  size_t residual_block_size = size % AES_BLOCK_SIZE;
+  // From CENC spec: CBC mode Initialization Vectors need not be unique per
-  size_t cbc_size = size - residual_block_size;
+  // sample or Subsample and may be generated randomly or sequentially, e.g.
-
+  // a per sample IV may be (1) equal to the cipher text of the last encrypted
-  // Encrypt everything but the residual block using CBC.
+  // cipher block (a continous cipher block chain across samples), or (2)
-  AES_cbc_encrypt(plaintext,
+  // generated by incrementing the previuos IV by the number of cipher blocks in the last
-                  ciphertext,
+  // sample or (3) by a fixed amount. We use method (1) here. No separate IV
-                  cbc_size,
+  // update is needed.
-                  aes_key_.get(),
-                  &iv[0],
-                  AES_ENCRYPT);
-  if (residual_block_size == 0) {
-    // No residual block. No need to do ciphertext stealing.
-    return true;
-  }
-
-  // Zero-pad the residual block and encrypt using CBC.
-  std::vector<uint8_t> residual_block(plaintext + size - residual_block_size,
-                                      plaintext + size);
-  residual_block.resize(AES_BLOCK_SIZE, 0);
-  AES_cbc_encrypt(&residual_block[0],
-                  &residual_block[0],
-                  AES_BLOCK_SIZE,
-                  aes_key_.get(),
-                  &iv[0],
-                  AES_ENCRYPT);
-
-  // Replace the last full block with the zero-padded, encrypted residual block,
-  // and replace the residual block with the equivalent portion of the last full
-  // encrypted block. It may appear that some encrypted bits of the last full
-  // block are lost, but they are not, as they were used as the IV when
-  // encrypting the zero-padded residual block.
-  uint8_t* residual_ciphertext_block = ciphertext + size - residual_block_size;
-  memcpy(residual_ciphertext_block,
-         residual_ciphertext_block - AES_BLOCK_SIZE,
-         residual_block_size);
-  memcpy(residual_ciphertext_block - AES_BLOCK_SIZE,
-         residual_block.data(),
-         AES_BLOCK_SIZE);
-  return true;
 }
 
-void AesCbcCtsEncryptor::UpdateIv() {}
+bool AesCbcEncryptor::SetIv(const std::vector<uint8_t>& iv) {
-
-bool AesCbcCtsEncryptor::SetIv(const std::vector<uint8_t>& iv) {
   if (iv.size() != AES_BLOCK_SIZE) {
     LOG(ERROR) << "Invalid IV size: " << iv.size();
     return false;
   }
 
-  iv_ = iv;
+  set_iv(iv);
   return true;
 }
 
+bool AesCbcEncryptor::EncryptInternal(const uint8_t* plaintext,
+                                      size_t plaintext_size,
+                                      uint8_t* ciphertext) {
+  DCHECK(aes_key());
+
+  const size_t residual_block_size = plaintext_size % AES_BLOCK_SIZE;
+  if (padding_scheme_ == kNoPadding && residual_block_size != 0) {
+    LOG(ERROR) << "Expecting input size to be multiple of " << AES_BLOCK_SIZE
+               << ", got " << plaintext_size;
+    return false;
+  }
+
+  // Encrypt everything but the residual block using CBC.
+  const size_t cbc_size = plaintext_size - residual_block_size;
+  std::vector<uint8_t> local_iv(iv());
+  if (cbc_size != 0) {
+    AES_cbc_encrypt(plaintext, ciphertext, cbc_size, aes_key(), local_iv.data(),
+                    AES_ENCRYPT);
+  } else if (padding_scheme_ == kCtsPadding) {
+    // Don't have a full block, leave unencrypted.
+    memcpy(ciphertext, plaintext, plaintext_size);
+    return true;
+  }
+  if (residual_block_size == 0 && padding_scheme_ != kPkcs5Padding) {
+    if (chain_across_calls_)
+      set_iv(local_iv);
+    // No residual block. No need to do padding.
+    return true;
+  }
+  DCHECK(!chain_across_calls_);
+
+  std::vector<uint8_t> residual_block(plaintext + cbc_size,
+                                      plaintext + plaintext_size);
+  DCHECK_EQ(residual_block.size(), residual_block_size);
+  uint8_t* residual_ciphertext_block = ciphertext + cbc_size;
+
+  if (padding_scheme_ == kPkcs5Padding) {
+    const size_t num_padding_bytes = AES_BLOCK_SIZE - residual_block_size;
+    DCHECK_EQ(num_padding_bytes, NumPaddingBytes(plaintext_size));
+    // Pad residue block with PKCS5 padding.
+    residual_block.resize(AES_BLOCK_SIZE, static_cast<char>(num_padding_bytes));
+    AES_cbc_encrypt(residual_block.data(), residual_ciphertext_block,
+                    AES_BLOCK_SIZE, aes_key(), local_iv.data(), AES_ENCRYPT);
+  } else {
+    DCHECK_EQ(padding_scheme_, kCtsPadding);
+
+    // Zero-pad the residual block and encrypt using CBC.
+    residual_block.resize(AES_BLOCK_SIZE, 0);
+    AES_cbc_encrypt(residual_block.data(), residual_block.data(),
+                    AES_BLOCK_SIZE, aes_key(), local_iv.data(), AES_ENCRYPT);
+
+    // Replace the last full block with the zero-padded, encrypted residual
+    // block, and replace the residual block with the equivalent portion of the
+    // last full encrypted block. It may appear that some encrypted bits of the
+    // last full block are lost, but they are not, as they were used as the IV
+    // when encrypting the zero-padded residual block.
+    memcpy(residual_ciphertext_block,
+           residual_ciphertext_block - AES_BLOCK_SIZE, residual_block_size);
+    memcpy(residual_ciphertext_block - AES_BLOCK_SIZE, residual_block.data(),
+           AES_BLOCK_SIZE);
+  }
+  return true;
+}
+
+size_t AesCbcEncryptor::NumPaddingBytes(size_t size) const {
+  return (padding_scheme_ == kPkcs5Padding)
+             ? (AES_BLOCK_SIZE - (size % AES_BLOCK_SIZE))
+             : 0;
+}
+
 }  // namespace media
 }  // namespace edash_packager

packager/media/base/aes_encryptor.h

@@ -29,52 +29,64 @@ class AesEncryptor {
   /// Initialize the encryptor with specified key and a random generated IV
   /// of the specified size.
   /// @return true on successful initialization, false otherwise.
-  virtual bool InitializeWithRandomIv(const std::vector<uint8_t>& key,
+  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.
-  virtual bool InitializeWithIv(const std::vector<uint8_t>& key,
+  bool InitializeWithIv(const std::vector<uint8_t>& key,
-                                const std::vector<uint8_t>& iv) = 0;
+                        const std::vector<uint8_t>& iv);
 
-  virtual size_t NumPaddingBytes(size_t size) = 0;
+  /// @name Various forms of encrypt calls.
-
-  /// @name Various forms of encrypt and decrypt calls.
   /// The plaintext and ciphertext pointers can be the same address.
-  /// @{
-  virtual bool EncryptData(const uint8_t* plaintext,
-                           size_t plaintext_size,
-                           uint8_t* ciphertext) = 0;
-
   bool Encrypt(const std::vector<uint8_t>& plaintext,
                std::vector<uint8_t>* ciphertext);
-
   bool Encrypt(const std::string& plaintext, std::string* ciphertext);
+  bool Encrypt(const uint8_t* plaintext,
+               size_t plaintext_size,
+               uint8_t* ciphertext) {
+    return EncryptInternal(plaintext, plaintext_size, ciphertext);
+  }
   /// @}
 
   /// Update IV for next sample.
   /// As recommended in ISO/IEC FDIS 23001-7:
   /// IV need to be updated per sample for CENC.
-  /// IV need not be unique per sample for CBC mode.
   virtual void UpdateIv() = 0;
 
   /// Set IV.
   /// @return true if successful, false if the input is invalid.
   virtual bool SetIv(const std::vector<uint8_t>& iv) = 0;
 
+  /// @return The current iv.
   const std::vector<uint8_t>& iv() const { return iv_; }
 
  protected:
+  /// Internal implementation of encrypt function.
+  /// @param plaintext points to the input plaintext.
+  /// @param plaintext_size is the size of input plaintext.
+  /// @param[out] ciphertext points to the output ciphertext. @a plaintext and
+  ///             @a ciphertext can point to the same address.
+  virtual bool EncryptInternal(const uint8_t* plaintext,
+                               size_t plaintext_size,
+                               uint8_t* ciphertext) = 0;
+  /// @param size specifies the input plaintext size.
+  /// @returns The number of padding bytes needed for output ciphertext.
+  virtual size_t NumPaddingBytes(size_t size) const = 0;
+
+  void set_iv(const std::vector<uint8_t>& iv) { iv_ = iv; }
+  AES_KEY* aes_key() const { return aes_key_.get(); }
+
+ private:
   // Initialization vector, with size 8 or 16.
   std::vector<uint8_t> iv_;
   // Openssl AES_KEY.
   scoped_ptr<AES_KEY> aes_key_;
 
- private:
   DISALLOW_COPY_AND_ASSIGN(AesEncryptor);
 };
 
-// Class which implements AES-CTR counter-mode encryption/decryption.
+// Class which implements AES-CTR counter-mode encryption.
 class AesCtrEncryptor : public AesEncryptor {
  public:
   AesCtrEncryptor();
@@ -82,18 +94,6 @@ class AesCtrEncryptor : public AesEncryptor {
 
   /// @name AesEncryptor implementation overrides.
   /// @{
-  /// @param key should be 16 bytes in size as specified in CENC spec.
-  /// @param iv_size should be either 8 or 16 as specified in CENC spec.
-  /// @return true on successful initialization, false otherwise.
-  bool InitializeWithIv(const std::vector<uint8_t>& key,
-                        const std::vector<uint8_t>& iv) override;
-
-  size_t NumPaddingBytes(size_t size) override;
-
-  bool EncryptData(const uint8_t* plaintext,
-                   size_t plaintext_size,
-                   uint8_t* ciphertext) override;
-
   /// Update IV for next sample. @a block_offset_ is reset to 0.
   /// As recommended in ISO/IEC FDIS 23001-7: CENC spec,
   ///   For 64-bit IV size, new_iv = old_iv + 1;
@@ -105,6 +105,12 @@ class AesCtrEncryptor : public AesEncryptor {
 
   uint32_t block_offset() const { return block_offset_; }
 
+ protected:
+  bool EncryptInternal(const uint8_t* plaintext,
+                       size_t plaintext_size,
+                       uint8_t* ciphertext) override;
+  size_t NumPaddingBytes(size_t size) const override;
+
  private:
   // Current block offset.
   uint32_t block_offset_;
@@ -118,58 +124,43 @@ class AesCtrEncryptor : public AesEncryptor {
   DISALLOW_COPY_AND_ASSIGN(AesCtrEncryptor);
 };
 
-// Class which implements AES-CBC (Cipher block chaining) encryption with
+enum CbcPaddingScheme {
-// PKCS#5 padding.
+  kNoPadding,
-class AesCbcPkcs5Encryptor : public AesEncryptor {
+  kPkcs5Padding,
- public:
+  kCtsPadding,
-  AesCbcPkcs5Encryptor();
-  ~AesCbcPkcs5Encryptor() override;
-
-  /// @name AesEncryptor implementation overrides.
-  /// @{
-  bool InitializeWithIv(const std::vector<uint8_t>& key,
-                        const std::vector<uint8_t>& iv) override;
-
-  size_t NumPaddingBytes(size_t size) override;
-
-  bool EncryptData(const uint8_t* plaintext,
-                   size_t plaintext_size,
-                   uint8_t* ciphertext) override;
-
-  void UpdateIv() override;
-
-  bool SetIv(const std::vector<uint8_t>& iv) override;
-  /// @}
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(AesCbcPkcs5Encryptor);
 };
 
-// Class which implements AES-CBC (Cipher block chaining) encryption with
+const bool kChainAcrossCalls = true;
-// Ciphertext stealing.
+
-class AesCbcCtsEncryptor : public AesEncryptor {
+// Class which implements AES-CBC (Cipher block chaining) encryption.
+class AesCbcEncryptor : public AesEncryptor {
  public:
-  AesCbcCtsEncryptor();
+  /// @param padding_scheme indicates the padding scheme used. Currently
-  ~AesCbcCtsEncryptor() override;
+  ///        supported schemes: kNoPadding, kPkcs5Padding, kCtsPadding.
+  /// @param chain_across_calls indicates whether there is a continuous cipher
+  ///        block chain across calls for Encrypt function. If it is false, iv
+  ///        is not updated across Encrypt function calls.
+  AesCbcEncryptor(CbcPaddingScheme padding_scheme, bool chain_across_calls);
+  ~AesCbcEncryptor() override;
 
   /// @name AesEncryptor implementation overrides.
   /// @{
-  bool InitializeWithIv(const std::vector<uint8_t>& key,
-                        const std::vector<uint8_t>& iv) override;
-
-  size_t NumPaddingBytes(size_t size) override;
-
-  bool EncryptData(const uint8_t* plaintext,
-                   size_t plaintext_size,
-                   uint8_t* ciphertext) override;
-
   void UpdateIv() override;
 
   bool SetIv(const std::vector<uint8_t>& iv) override;
   /// @}
 
+ protected:
+  bool EncryptInternal(const uint8_t* plaintext,
+                       size_t plaintext_size,
+                       uint8_t* ciphertext) override;
+  size_t NumPaddingBytes(size_t size) const override;
+
  private:
-  DISALLOW_COPY_AND_ASSIGN(AesCbcCtsEncryptor);
+  const CbcPaddingScheme padding_scheme_;
+  const bool chain_across_calls_;
+
+  DISALLOW_COPY_AND_ASSIGN(AesCbcEncryptor);
 };
 
 }  // namespace media

packager/media/base/aes_encryptor_unittest.cc

@@ -170,7 +170,7 @@ TEST_F(AesCtrEncryptorTest, NistTestCase) {
 
 TEST_F(AesCtrEncryptorTest, NistTestCaseInplaceEncryptionDecryption) {
   std::vector<uint8_t> buffer = plaintext_;
-  EXPECT_TRUE(encryptor_.EncryptData(&buffer[0], buffer.size(), &buffer[0]));
+  EXPECT_TRUE(encryptor_.Encrypt(&buffer[0], buffer.size(), &buffer[0]));
   EXPECT_EQ(ciphertext_, buffer);
 
   EXPECT_TRUE(decryptor_.SetIv(iv_));
@@ -211,12 +211,11 @@ TEST_F(AesCtrEncryptorTest, 128BitIVBoundaryCaseEncryption) {
 
   ASSERT_TRUE(encryptor_.InitializeWithIv(key_, iv_max64));
   std::vector<uint8_t> encrypted_verify(plaintext_.size(), 0);
-  EXPECT_TRUE(encryptor_.EncryptData(&plaintext_[0], kAesBlockSize,
+  EXPECT_TRUE(
-                                     &encrypted_verify[0]));
+      encryptor_.Encrypt(&plaintext_[0], kAesBlockSize, &encrypted_verify[0]));
   std::vector<uint8_t> iv_zero(kIv128Zero, kIv128Zero + arraysize(kIv128Zero));
   ASSERT_TRUE(encryptor_.InitializeWithIv(key_, iv_zero));
-  EXPECT_TRUE(encryptor_.EncryptData(&plaintext_[kAesBlockSize],
+  EXPECT_TRUE(encryptor_.Encrypt(&plaintext_[kAesBlockSize], kAesBlockSize * 3,
-                                     kAesBlockSize * 3,
                                  &encrypted_verify[kAesBlockSize]));
   EXPECT_EQ(encrypted, encrypted_verify);
 }
@@ -254,7 +253,7 @@ TEST_P(AesCtrEncryptorSubsampleTest, NistTestCaseSubsamples) {
   for (uint32_t i = 0, offset = 0; i < test_case->subsample_count; ++i) {
     uint32_t len = test_case->subsample_sizes[i];
     EXPECT_TRUE(
-        encryptor_.EncryptData(&plaintext_[offset], len, &encrypted[offset]));
+        encryptor_.Encrypt(&plaintext_[offset], len, &encrypted[offset]));
     offset += len;
     EXPECT_EQ(offset % kAesBlockSize, encryptor_.block_offset());
   }
@@ -301,30 +300,66 @@ INSTANTIATE_TEST_CASE_P(IvTestCases,
                         AesCtrEncryptorIvTest,
                         ::testing::ValuesIn(kIvTestCases));
 
-class AesCbcPkcs5EncryptorTestEncryptionDecryption : public testing::Test {
+class AesCbcEncryptDecryptTest {
  public:
-  void TestEncryptionDecryption(const std::vector<uint8_t>& key,
+  AesCbcEncryptDecryptTest()
-                                const std::vector<uint8_t>& iv,
+      : encryptor_(new AesCbcEncryptor(kPkcs5Padding, !kChainAcrossCalls)),
-                                const std::string& plaintext,
+        decryptor_(new AesCbcDecryptor(kPkcs5Padding, !kChainAcrossCalls)),
-                                const std::string& expected_ciphertext_hex) {
+        key_(kAesKey, kAesKey + arraysize(kAesKey)),
-    AesCbcPkcs5Encryptor encryptor;
+        iv_(kAesIv, kAesIv + arraysize(kAesIv)) {}
-    EXPECT_TRUE(encryptor.InitializeWithIv(key, iv));
 
-    std::string ciphertext;
+  void TestEncryptDecrypt(const std::vector<uint8_t>& plaintext,
-    encryptor.Encrypt(plaintext, &ciphertext);
+                          const std::vector<uint8_t>& expected_ciphertext) {
-    EXPECT_EQ(expected_ciphertext_hex,
+    // Test Vector form.
-              base::HexEncode(ciphertext.data(), ciphertext.size()));
+    TestEncryptDecryptSeparateBuffers(plaintext, expected_ciphertext);
+    TestEncryptDecryptInPlace(plaintext, expected_ciphertext);
 
-    AesCbcPkcs5Decryptor decryptor;
+    // Test string form.
-    ASSERT_TRUE(decryptor.InitializeWithIv(key, iv));
+    std::string plaintext_str(plaintext.begin(), plaintext.end());
+    std::string expected_ciphertext_str(expected_ciphertext.begin(),
+                                        expected_ciphertext.end());
+    TestEncryptDecryptSeparateBuffers(plaintext_str, expected_ciphertext_str);
+    TestEncryptDecryptInPlace(plaintext_str, expected_ciphertext_str);
+  }
 
-    std::string decrypted;
+ protected:
-    EXPECT_TRUE(decryptor.Decrypt(ciphertext, &decrypted));
+  template <class T>
+  void TestEncryptDecryptSeparateBuffers(const T& plaintext,
+                                         const T& expected_ciphertext) {
+    ASSERT_TRUE(encryptor_->InitializeWithIv(key_, iv_));
+    ASSERT_TRUE(decryptor_->InitializeWithIv(key_, iv_));
+
+    T encrypted;
+    EXPECT_TRUE(encryptor_->Encrypt(plaintext, &encrypted));
+    EXPECT_EQ(expected_ciphertext, encrypted);
+
+    T decrypted;
+    EXPECT_TRUE(decryptor_->Decrypt(encrypted, &decrypted));
     EXPECT_EQ(plaintext, decrypted);
   }
+
+  template <class T>
+  void TestEncryptDecryptInPlace(const T& plaintext,
+                                 const T& expected_ciphertext) {
+    ASSERT_TRUE(encryptor_->InitializeWithIv(key_, iv_));
+    ASSERT_TRUE(decryptor_->InitializeWithIv(key_, iv_));
+
+    T buffer(plaintext);
+    EXPECT_TRUE(encryptor_->Encrypt(buffer, &buffer));
+    EXPECT_EQ(expected_ciphertext, buffer);
+    EXPECT_TRUE(decryptor_->Decrypt(buffer, &buffer));
+    EXPECT_EQ(plaintext, buffer);
+  }
+
+  scoped_ptr<AesCbcEncryptor> encryptor_;
+  scoped_ptr<AesCbcDecryptor> decryptor_;
+  std::vector<uint8_t> key_;
+  std::vector<uint8_t> iv_;
 };
 
-TEST_F(AesCbcPkcs5EncryptorTestEncryptionDecryption, EncryptAES256CBC) {
+class AesCbcTest : public AesCbcEncryptDecryptTest, public testing::Test {};
+
+TEST_F(AesCbcTest, Aes256CbcPkcs5) {
   // NIST SP 800-38A test vector F.2.5 CBC-AES256.Encrypt.
   static const uint8_t kAesCbcKey[] = {
       0x60, 0x3d, 0xeb, 0x10, 0x15, 0xca, 0x71, 0xbe, 0x2b, 0x73, 0xae,
@@ -363,18 +398,17 @@ TEST_F(AesCbcPkcs5EncryptorTestEncryptionDecryption, EncryptAES256CBC) {
       0x3f, 0x46, 0x17, 0x96, 0xd6, 0xb0, 0xd6, 0xb2,
       0xe0, 0xc2, 0xa7, 0x2b, 0x4d, 0x80, 0xe6, 0x44};
 
-  const std::vector<uint8_t> key(kAesCbcKey,
+  key_.assign(kAesCbcKey, kAesCbcKey + arraysize(kAesCbcKey));
-                                 kAesCbcKey + arraysize(kAesCbcKey));
+  iv_.assign(kAesCbcIv, kAesCbcIv + arraysize(kAesCbcIv));
-  const std::vector<uint8_t> iv(kAesCbcIv, kAesCbcIv + arraysize(kAesCbcIv));
+  const std::vector<uint8_t> plaintext(
-  const std::string plaintext(reinterpret_cast<const char*>(kAesCbcPlaintext),
+      kAesCbcPlaintext, kAesCbcPlaintext + arraysize(kAesCbcPlaintext));
-                              sizeof(kAesCbcPlaintext));
+  const std::vector<uint8_t> expected_ciphertext(
-  const std::string expected_ciphertext_hex =
+      kAesCbcCiphertext, kAesCbcCiphertext + arraysize(kAesCbcCiphertext));
-      base::HexEncode(kAesCbcCiphertext, sizeof(kAesCbcCiphertext));
 
-  TestEncryptionDecryption(key, iv, plaintext, expected_ciphertext_hex);
+  TestEncryptDecrypt(plaintext, expected_ciphertext);
 }
 
-TEST_F(AesCbcPkcs5EncryptorTestEncryptionDecryption, EncryptAES128CBCRegression) {
+TEST_F(AesCbcTest, Aes128CbcPkcs5) {
   const std::string kKey = "128=SixteenBytes";
   const std::string kIv = "Sweet Sixteen IV";
   const std::string kPlaintext =
@@ -383,172 +417,201 @@ TEST_F(AesCbcPkcs5EncryptorTestEncryptionDecryption, EncryptAES128CBCRegression)
       "D4A67A0BA33C30F207344D81D1E944BBE65587C3D7D9939A"
       "C070C62B9C15A3EA312EA4AD1BC7929F4D3C16B03AD5ADA8";
 
-  const std::vector<uint8_t> key(kKey.begin(), kKey.end());
+  key_.assign(kKey.begin(), kKey.end());
-  const std::vector<uint8_t> iv(kIv.begin(), kIv.end());
+  iv_.assign(kIv.begin(), kIv.end());
 
-  TestEncryptionDecryption(key, iv, kPlaintext, kExpectedCiphertextHex);
+  const std::vector<uint8_t> plaintext(kPlaintext.begin(), kPlaintext.end());
+  std::vector<uint8_t> expected_ciphertext;
+  ASSERT_TRUE(
+      base::HexStringToBytes(kExpectedCiphertextHex, &expected_ciphertext));
+  TestEncryptDecrypt(plaintext, expected_ciphertext);
 }
 
-TEST_F(AesCbcPkcs5EncryptorTestEncryptionDecryption, EncryptAES192CBCRegression) {
+TEST_F(AesCbcTest, Aes192CbcPkcs5) {
   const std::string kKey = "192bitsIsTwentyFourByte!";
   const std::string kIv = "Sweet Sixteen IV";
   const std::string kPlaintext = "Small text";
   const std::string kExpectedCiphertextHex = "78DE5D7C2714FC5C61346C5416F6C89A";
 
-  const std::vector<uint8_t> key(kKey.begin(), kKey.end());
-  const std::vector<uint8_t> iv(kIv.begin(), kIv.end());
-
-  TestEncryptionDecryption(key, iv, kPlaintext, kExpectedCiphertextHex);
-}
-
-class AesCbcPkcs5EncryptorTest : public testing::Test {
- public:
-  void SetUp() override {
-    const std::string kKey = "128=SixteenBytes";
-    const std::string kIv = "Sweet Sixteen IV";
   key_.assign(kKey.begin(), kKey.end());
   iv_.assign(kIv.begin(), kIv.end());
-  }
 
- protected:
+  const std::vector<uint8_t> plaintext(kPlaintext.begin(), kPlaintext.end());
-  std::vector<uint8_t> key_;
+  std::vector<uint8_t> expected_ciphertext;
-  std::vector<uint8_t> iv_;
+  ASSERT_TRUE(
-};
+      base::HexStringToBytes(kExpectedCiphertextHex, &expected_ciphertext));
-
+  TestEncryptDecrypt(plaintext, expected_ciphertext);
-TEST_F(AesCbcPkcs5EncryptorTest, UnsupportedKeySize) {
-  AesCbcPkcs5Encryptor encryptor;
-  EXPECT_FALSE(encryptor.InitializeWithIv(std::vector<uint8_t>(15, 0), iv_));
 }
 
-TEST_F(AesCbcPkcs5EncryptorTest, UnsupportedIvSize) {
+TEST_F(AesCbcTest, NoPaddingNoChainAcrossCalls) {
-  AesCbcPkcs5Encryptor encryptor;
+  const uint8_t kPlaintext[] = {
-  EXPECT_FALSE(encryptor.InitializeWithIv(key_, std::vector<uint8_t>(14, 0)));
+      0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
-}
+      0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+  };
+  const uint8_t kCiphertext[] = {
+      0x77, 0xcd, 0xe9, 0x1f, 0xe6, 0xdf, 0x9c, 0xbc,
+      0x5d, 0x0c, 0x98, 0xf9, 0x6e, 0xfd, 0x59, 0x0b,
+  };
 
-TEST_F(AesCbcPkcs5EncryptorTest, EmptyEncrypt) {
+  std::vector<uint8_t> plaintext(kPlaintext,
-  AesCbcPkcs5Encryptor encryptor;
+                                 kPlaintext + arraysize(kPlaintext));
+  std::vector<uint8_t> ciphertext(kCiphertext,
+                                  kCiphertext + arraysize(kCiphertext));
+
+  AesCbcEncryptor encryptor(kNoPadding, !kChainAcrossCalls);
   ASSERT_TRUE(encryptor.InitializeWithIv(key_, iv_));
 
-  std::string ciphertext;
+  std::vector<uint8_t> encrypted;
-  std::string expected_ciphertext_hex = "8518B8878D34E7185E300D0FCC426396";
+  ASSERT_TRUE(encryptor.Encrypt(plaintext, &encrypted));
-  encryptor.Encrypt("", &ciphertext);
+  EXPECT_EQ(ciphertext, encrypted);
-  EXPECT_EQ(expected_ciphertext_hex,
+  // Iv should not have been updated.
-            base::HexEncode(ciphertext.data(), ciphertext.size()));
+  EXPECT_EQ(iv_, encryptor.iv());
-}
+  ASSERT_TRUE(encryptor.Encrypt(plaintext, &encrypted));
+  EXPECT_EQ(ciphertext, encrypted);
 
-TEST_F(AesCbcPkcs5EncryptorTest, CipherTextNotMultipleOfBlockSize) {
+  AesCbcDecryptor decryptor(kNoPadding, !kChainAcrossCalls);
-  AesCbcPkcs5Decryptor decryptor;
   ASSERT_TRUE(decryptor.InitializeWithIv(key_, iv_));
 
-  std::string plaintext;
+  std::vector<uint8_t> decrypted;
-  EXPECT_FALSE(decryptor.Decrypt("1", &plaintext));
+  ASSERT_TRUE(decryptor.Decrypt(ciphertext, &decrypted));
+  EXPECT_EQ(plaintext, decrypted);
+  // Iv should not have been updated.
+  EXPECT_EQ(iv_, encryptor.iv());
+  ASSERT_TRUE(decryptor.Decrypt(ciphertext, &decrypted));
+  EXPECT_EQ(plaintext, decrypted);
 }
 
-class AesCbcCtsEncryptorDecryptorTest : public testing::Test {
+TEST_F(AesCbcTest, NoPaddingChainAcrossCalls) {
- public:
+  const uint8_t kPlaintext[] = {
-  void SetUp() override {
+      0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
-    key_.assign(kAesKey, kAesKey + arraysize(kAesKey));
+      0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
-    iv_.assign(kAesIv, kAesIv + arraysize(kAesIv));
+  };
-  }
+  const uint8_t kCiphertext[] = {
+      0x77, 0xcd, 0xe9, 0x1f, 0xe6, 0xdf, 0x9c, 0xbc,
+      0x5d, 0x0c, 0x98, 0xf9, 0x6e, 0xfd, 0x59, 0x0b,
+  };
+  const uint8_t kCiphertext2[] = {
+      0xbd, 0xdd, 0xe4, 0x39, 0x52, 0x6f, 0x10, 0x0c,
+      0x95, 0x45, 0xc2, 0x74, 0xd4, 0xf7, 0xfd, 0x3f,
+  };
 
-  void TestEncryptDecryptSeparateBuffers(
+  std::vector<uint8_t> plaintext(kPlaintext,
-      const std::vector<uint8_t>& plaintext,
+                                 kPlaintext + arraysize(kPlaintext));
-      const std::vector<uint8_t>& expected_ciphertext) {
+  std::vector<uint8_t> ciphertext(kCiphertext,
-    ASSERT_TRUE(encryptor_.InitializeWithIv(key_, iv_));
+                                  kCiphertext + arraysize(kCiphertext));
-    ASSERT_TRUE(decryptor_.InitializeWithIv(key_, iv_));
+  std::vector<uint8_t> ciphertext2(kCiphertext2,
+                                   kCiphertext2 + arraysize(kCiphertext2));
+
+  AesCbcEncryptor encryptor(kNoPadding, kChainAcrossCalls);
+  ASSERT_TRUE(encryptor.InitializeWithIv(key_, iv_));
 
   std::vector<uint8_t> encrypted;
-    encryptor_.Encrypt(plaintext, &encrypted);
+  ASSERT_TRUE(encryptor.Encrypt(plaintext, &encrypted));
-    EXPECT_EQ(expected_ciphertext, encrypted);
+  EXPECT_EQ(ciphertext, encrypted);
+  // Iv should have been updated.
+  EXPECT_NE(iv_, encryptor.iv());
+  // If run encrypt again, the result will be different.
+  ASSERT_TRUE(encryptor.Encrypt(plaintext, &encrypted));
+  EXPECT_EQ(ciphertext2, encrypted);
+
+  AesCbcDecryptor decryptor(kNoPadding, kChainAcrossCalls);
+  ASSERT_TRUE(decryptor.InitializeWithIv(key_, iv_));
 
   std::vector<uint8_t> decrypted;
-    decryptor_.Decrypt(encrypted, &decrypted);
+  ASSERT_TRUE(decryptor.Decrypt(ciphertext, &decrypted));
   EXPECT_EQ(plaintext, decrypted);
-  }
+  // Iv should have been updated.
+  EXPECT_NE(iv_, encryptor.iv());
+  // If run decrypt on ciphertext2 now, it will return the original plaintext.
+  ASSERT_TRUE(decryptor.Decrypt(ciphertext2, &decrypted));
+  EXPECT_EQ(plaintext, decrypted);
+}
 
-  void TestEncryptDecryptInPlace(
+TEST_F(AesCbcTest, UnsupportedKeySize) {
-      const std::vector<uint8_t>& plaintext,
+  EXPECT_FALSE(encryptor_->InitializeWithIv(std::vector<uint8_t>(15, 0), iv_));
-      const std::vector<uint8_t>& expected_ciphertext) {
+  EXPECT_FALSE(decryptor_->InitializeWithIv(std::vector<uint8_t>(15, 0), iv_));
-    ASSERT_TRUE(encryptor_.InitializeWithIv(key_, iv_));
+}
-    ASSERT_TRUE(decryptor_.InitializeWithIv(key_, iv_));
 
-    std::vector<uint8_t> buffer(plaintext);
+TEST_F(AesCbcTest, UnsupportedIvSize) {
-    encryptor_.Encrypt(buffer, &buffer);
+  EXPECT_FALSE(encryptor_->InitializeWithIv(key_, std::vector<uint8_t>(14, 0)));
-    EXPECT_EQ(expected_ciphertext, buffer);
+  EXPECT_FALSE(decryptor_->InitializeWithIv(key_, std::vector<uint8_t>(8, 0)));
-    decryptor_.Decrypt(buffer, &buffer);
+}
-    EXPECT_EQ(plaintext, buffer);
-  }
 
- protected:
+TEST_F(AesCbcTest, Pkcs5CipherTextNotMultipleOfBlockSize) {
-  std::vector<uint8_t> key_;
+  std::string plaintext;
-  std::vector<uint8_t> iv_;
+  ASSERT_TRUE(decryptor_->InitializeWithIv(key_, iv_));
-  AesCbcCtsEncryptor encryptor_;
+  EXPECT_FALSE(decryptor_->Decrypt("1", &plaintext));
-  AesCbcCtsDecryptor decryptor_;
+}
+
+TEST_F(AesCbcTest, Pkcs5CipherTextEmpty) {
+  std::string plaintext;
+  ASSERT_TRUE(decryptor_->InitializeWithIv(key_, iv_));
+  EXPECT_FALSE(decryptor_->Decrypt("", &plaintext));
+}
+
+struct CbcTestCase {
+  CbcPaddingScheme padding_scheme;
+  const char* plaintext_hex;
+  const char* expected_ciphertext_hex;
 };
 
-TEST_F(AesCbcCtsEncryptorDecryptorTest, TestWithResidualBytes) {
+const CbcTestCase kCbcTestCases[] = {
-  std::vector<uint8_t> plaintext;
+    // No padding with zero bytes.
-  ASSERT_TRUE(base::HexStringToBytes(
+    {kNoPadding, "", ""},
+    {kNoPadding,
+     "6bc1bee22e409f96e93d7e117393172a6bc1bee22e409f96e93d7e117393172a",
+     "77cde91fe6df9cbc5d0c98f96efd590bbddde439526f100c9545c274d4f7fd3f"},
+    // Pkcs5 padding with zero bytes.
+    {kPkcs5Padding, "", "f6a3569dea3cda208eb3d5792942612b"},
+    // Cts Padding with zero bytes.
+    {kCtsPadding, "", ""},
+    // Cts Padding with no encrypted blocks.
+    {kCtsPadding, "3f593e7a204a5e70f2", "3f593e7a204a5e70f2"},
+    // Cts padding with residual bytes.
+    {kCtsPadding,
      "e0818f2dc7caaa9edf09285a0c1fca98d39e9b08a47ab6911c4bbdf27d94"
      "f917cdffc9ebb307141f23b0d3921e0ed7f86eb09381286f8e7a4f",
-      &plaintext));
-
-  std::vector<uint8_t> ciphertext;
-  ASSERT_TRUE(base::HexStringToBytes(
      "b40a0b8704c74e22e8030cad6f272b34ace54cc7c9c64b2018bbcf23df018"
-      "39b14899441cf74a9fb2f2b229a609146f31be8e8a826eb6e857e",
+     "39b14899441cf74a9fb2f2b229a609146f31be8e8a826eb6e857e"},
-      &ciphertext));
+    // Cts padding with even blocks.
-
+    {kCtsPadding,
-  TestEncryptDecryptSeparateBuffers(plaintext, ciphertext);
-  TestEncryptDecryptInPlace(plaintext, ciphertext);
-}
-
-TEST_F(AesCbcCtsEncryptorDecryptorTest, TestEvenBlocks) {
-  std::vector<uint8_t> plaintext;
-  ASSERT_TRUE(base::HexStringToBytes(
      "3f593e7a204a5e70f2814dca05aa49d36f2daddc9a24e0515802c539efc3"
      "1094b3ad6c26d6f5c0e387545ce6a4c2c14d",
-      &plaintext));
-
-  std::vector<uint8_t> ciphertext;
-  ASSERT_TRUE(base::HexStringToBytes(
      "5f32cd0504b27b25ee04090d88d37d340c9c0a9fa50b05358b98fad4302ea"
-      "480148d8aa091f4e7d186a7223df153f6f7",
+     "480148d8aa091f4e7d186a7223df153f6f7"},
-      &ciphertext));
+    // Cts padding with one block and a half.
+    {kCtsPadding, "3f593e7a204a5e70f2814dca05aa49d36f2daddc9a4302ea",
+     "623fc113fe02ce85628deb58d652c6995f32cd0504b27b25"},
+};
 
-  TestEncryptDecryptSeparateBuffers(plaintext, ciphertext);
+class AesCbcCryptorVerificationTest
-  TestEncryptDecryptInPlace(plaintext, ciphertext);
+    : public AesCbcEncryptDecryptTest,
-}
+      public ::testing::TestWithParam<CbcTestCase> {};
+
+TEST_P(AesCbcCryptorVerificationTest, EncryptDecryptTest) {
+  encryptor_.reset(
+      new AesCbcEncryptor(GetParam().padding_scheme, !kChainAcrossCalls));
+  decryptor_.reset(
+      new AesCbcDecryptor(GetParam().padding_scheme, !kChainAcrossCalls));
 
-TEST_F(AesCbcCtsEncryptorDecryptorTest, TestOneBlockAndAHalf) {
   std::vector<uint8_t> plaintext;
-  ASSERT_TRUE(base::HexStringToBytes(
+  std::string plaintext_hex(GetParam().plaintext_hex);
-      "3f593e7a204a5e70f2814dca05aa49d36f2daddc9a4302ea",
+  if (!plaintext_hex.empty())
-      &plaintext));
+    ASSERT_TRUE(base::HexStringToBytes(plaintext_hex, &plaintext));
 
-  std::vector<uint8_t> ciphertext;
+  std::vector<uint8_t> expected_ciphertext;
-  ASSERT_TRUE(base::HexStringToBytes(
+  std::string expected_ciphertext_hex(GetParam().expected_ciphertext_hex);
-      "623fc113fe02ce85628deb58d652c6995f32cd0504b27b25",
+  if (!expected_ciphertext_hex.empty()) {
-      &ciphertext));
+    ASSERT_TRUE(base::HexStringToBytes(GetParam().expected_ciphertext_hex,
+                                       &expected_ciphertext));
+  }
 
-  TestEncryptDecryptSeparateBuffers(plaintext, ciphertext);
+  TestEncryptDecrypt(plaintext, expected_ciphertext);
-  TestEncryptDecryptInPlace(plaintext, ciphertext);
 }
 
-TEST_F(AesCbcCtsEncryptorDecryptorTest, TestZeroEncryptedBlocks) {
+INSTANTIATE_TEST_CASE_P(CbcTestCases,
-  std::vector<uint8_t> plaintext;
+                        AesCbcCryptorVerificationTest,
-  ASSERT_TRUE(base::HexStringToBytes("3f593e7a204a5e70f2", &plaintext));
+                        ::testing::ValuesIn(kCbcTestCases));
-
-  TestEncryptDecryptSeparateBuffers(plaintext, plaintext);
-  TestEncryptDecryptInPlace(plaintext, plaintext);
-}
-
-TEST_F(AesCbcCtsEncryptorDecryptorTest, TestZeroBytes) {
-  std::vector<uint8_t> plaintext;
-
-  TestEncryptDecryptSeparateBuffers(plaintext, plaintext);
-  TestEncryptDecryptInPlace(plaintext, plaintext);
-}
 
 }  // namespace media
 }  // namespace edash_packager

packager/media/base/decryptor_source.cc

@@ -44,7 +44,7 @@ bool DecryptorSource::DecryptSampleBuffer(const DecryptConfig* decrypt_config,
         aes_decryptor.reset(new AesCtrDecryptor);
         break;
       case kEncryptionModeAesCbc:
-        aes_decryptor.reset(new AesCbcPkcs5Decryptor);
+        aes_decryptor.reset(new AesCbcDecryptor(kNoPadding, kChainAcrossCalls));
         break;
       default:
         LOG(ERROR) << "Unsupported Decryption Mode: "

packager/media/base/request_signer.cc

@@ -19,7 +19,7 @@ RequestSigner::RequestSigner(const std::string& signer_name)
 RequestSigner::~RequestSigner() {}
 
 AesRequestSigner::AesRequestSigner(const std::string& signer_name,
-                                   scoped_ptr<AesCbcPkcs5Encryptor> encryptor)
+                                   scoped_ptr<AesCbcEncryptor> encryptor)
     : RequestSigner(signer_name), aes_cbc_encryptor_(encryptor.Pass()) {
   DCHECK(aes_cbc_encryptor_);
 }
@@ -39,7 +39,8 @@ AesRequestSigner* AesRequestSigner::CreateSigner(const std::string& signer_name,
     return NULL;
   }
 
-  scoped_ptr<AesCbcPkcs5Encryptor> encryptor(new AesCbcPkcs5Encryptor());
+  scoped_ptr<AesCbcEncryptor> encryptor(
+      new AesCbcEncryptor(kPkcs5Padding, !kChainAcrossCalls));
   if (!encryptor->InitializeWithIv(aes_key, iv))
     return NULL;
   return new AesRequestSigner(signer_name, encryptor.Pass());

packager/media/base/request_signer.h

@@ -14,7 +14,7 @@
 namespace edash_packager {
 namespace media {
 
-class AesCbcPkcs5Encryptor;
+class AesCbcEncryptor;
 class RsaPrivateKey;
 
 /// Abstract class used for signature generation.
@@ -56,9 +56,9 @@ class AesRequestSigner : public RequestSigner {
 
  private:
   AesRequestSigner(const std::string& signer_name,
-                   scoped_ptr<AesCbcPkcs5Encryptor> encryptor);
+                   scoped_ptr<AesCbcEncryptor> encryptor);
 
-  scoped_ptr<AesCbcPkcs5Encryptor> aes_cbc_encryptor_;
+  scoped_ptr<AesCbcEncryptor> aes_cbc_encryptor_;
 
   DISALLOW_COPY_AND_ASSIGN(AesRequestSigner);
 };

packager/media/formats/mp4/encrypting_fragmenter.cc

@@ -23,7 +23,8 @@ namespace mp4 {
 
 namespace {
 // Generate 64bit IV by default.
-const size_t kDefaultIvSize = 8u;
+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
@@ -175,16 +176,19 @@ 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 AesCbcPkcs5Encryptor);
+    encryptor.reset(new AesCbcEncryptor(kNoPadding, kChainAcrossCalls));
+    default_iv_size = kDefaultIvSizeForCbc;
   } else {
     return Status(error::MUXER_FAILURE, "Unsupported encryption mode.");
   }
   const bool initialized = encryption_key_->iv.empty()
                                ? encryptor->InitializeWithRandomIv(
-                                     encryption_key_->key, kDefaultIvSize)
+                                     encryption_key_->key, default_iv_size)
                                : encryptor->InitializeWithIv(
                                      encryption_key_->key, encryption_key_->iv);
   if (!initialized)
@@ -195,7 +199,7 @@ Status EncryptingFragmenter::CreateEncryptor() {
 
 void EncryptingFragmenter::EncryptBytes(uint8_t* data, uint32_t size) {
   DCHECK(encryptor_);
-  CHECK(encryptor_->EncryptData(data, size, data));
+  CHECK(encryptor_->Encrypt(data, size, data));
 }
 
 Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
@@ -223,8 +227,11 @@ Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
         // encrypted bytes of each frame within the superframe must be block
         // aligned so that the counter state can be computed for each frame
         // within the superframe.
-        if (is_superframe) {
+        // For AES-CBC mode 'cbc1' scheme, clear data is sized appropriately so
-          uint16_t misalign_bytes = subsample.cipher_bytes % kCencBlockSize;
+        // that the cipher data is block aligned.
+        if (is_superframe || encryption_mode_ == kEncryptionModeAesCbc) {
+          const uint16_t misalign_bytes =
+              subsample.cipher_bytes % kCencBlockSize;
           subsample.clear_bytes += misalign_bytes;
           subsample.cipher_bytes -= misalign_bytes;
         }
@@ -258,10 +265,18 @@ Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
           if (video_slice_header_size < 0)
             return Status(error::MUXER_FAILURE, "Failed to read slice header.");
 
-          const uint64_t current_clear_bytes = nalu.header_size() +
+          uint64_t current_clear_bytes =
-                                               video_slice_header_size;
+              nalu.header_size() + video_slice_header_size;
-          const uint64_t cipher_bytes =
+          uint64_t cipher_bytes = nalu.payload_size() - video_slice_header_size;
-              nalu.payload_size() - video_slice_header_size;
+
+          // For AES-CBC mode 'cbc1' scheme, clear data is sized appropriately
+          // so that the cipher data is block aligned.
+          if (encryption_mode_ == kEncryptionModeAesCbc) {
+            const uint16_t misalign_bytes = cipher_bytes % kCencBlockSize;
+            current_clear_bytes += misalign_bytes;
+            cipher_bytes -= misalign_bytes;
+          }
+
           const uint8_t* nalu_data = nalu.data() + current_clear_bytes;
           EncryptBytes(const_cast<uint8_t*>(nalu_data), cipher_bytes);
 
@@ -285,7 +300,12 @@ Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
     traf()->auxiliary_size.sample_info_sizes.push_back(
         sample_encryption_entry.ComputeSize());
   } else {
-    EncryptBytes(data, sample->data_size());
+    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)
+      encryption_data_size -= encryption_data_size % kCencBlockSize;
+    EncryptBytes(data, encryption_data_size);
   }
 
   traf()->sample_encryption.sample_encryption_entries.push_back(

packager/media/formats/webm/encryptor.cc

@@ -78,7 +78,7 @@ Status Encryptor::EncryptFrame(scoped_refptr<MediaSample> sample,
     uint8_t* sample_data = sample->writable_data();
 
     // Encrypt the data in-place.
-    if (!encryptor_->EncryptData(sample_data, sample_size, sample_data)) {
+    if (!encryptor_->Encrypt(sample_data, sample_size, sample_data)) {
       return Status(error::MUXER_FAILURE, "Failed to encrypt the frame.");
     }
 

packager/media/formats/wvm/wvm_media_parser.cc

@@ -1114,7 +1114,7 @@ bool WvmMediaParser::ProcessEcm() {
       encryption_key.key.begin(),
       encryption_key.key.begin() + kAssetKeySizeBytes);
   std::vector<uint8_t> iv(kInitializationVectorSizeBytes);
-  AesCbcCtsDecryptor asset_decryptor;
+  AesCbcDecryptor asset_decryptor(kCtsPadding, !kChainAcrossCalls);
   if (!asset_decryptor.InitializeWithIv(asset_key, iv)) {
     LOG(ERROR) << "Failed to initialize asset_decryptor.";
     return false;
@@ -1124,13 +1124,14 @@ bool WvmMediaParser::ProcessEcm() {
       kEcmFlagsSizeBytes + kEcmContentKeySizeBytes +
       kEcmPaddingSizeBytes;  // flags + contentKey + padding.
   std::vector<uint8_t> content_key_buffer(content_key_buffer_size);
-  asset_decryptor.Decrypt(ecm_data, content_key_buffer_size,
+  CHECK(asset_decryptor.Decrypt(ecm_data, content_key_buffer_size,
-                          content_key_buffer.data());
+                                content_key_buffer.data()));
 
   std::vector<uint8_t> decrypted_content_key_vec(
       content_key_buffer.begin() + 4,
       content_key_buffer.begin() + 20);
-  scoped_ptr<AesCbcCtsDecryptor> content_decryptor(new AesCbcCtsDecryptor);
+  scoped_ptr<AesCbcDecryptor> content_decryptor(
+      new AesCbcDecryptor(kCtsPadding, !kChainAcrossCalls));
   if (!content_decryptor->InitializeWithIv(decrypted_content_key_vec, iv)) {
     LOG(ERROR) << "Failed to initialize content decryptor.";
     return false;

packager/media/formats/wvm/wvm_media_parser.h

@@ -20,7 +20,7 @@
 namespace edash_packager {
 namespace media {
 
-class AesCbcCtsDecryptor;
+class AesCbcDecryptor;
 class KeySource;
 struct EncryptionKey;
 
@@ -252,7 +252,7 @@ class WvmMediaParser : public MediaParser {
   std::deque<DemuxStreamIdMediaSample> media_sample_queue_;
   std::vector<uint8_t> sample_data_;
   KeySource* decryption_key_source_;
-  scoped_ptr<AesCbcCtsDecryptor> content_decryptor_;
+  scoped_ptr<AesCbcDecryptor> content_decryptor_;
 
   DISALLOW_COPY_AND_ASSIGN(WvmMediaParser);
 };