Add support for encrypted WebM files as defined in the RFC.

media/crypto/hmac_aes_decryptor_unittest.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/sys_byteorder.h"
+#include "media/base/decoder_buffer.h"
+#include "media/base/decrypt_config.h"
+#include "media/crypto/hmac_aes_decryptor.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media {
+
+struct WebmEncryptedData {
+  uint8 plain_text[32];
+  int plain_text_size;
+  uint8 key_id[32];
+  int key_id_size;
+  uint8 key[32];
+  int key_size;
+  uint8 encrypted_data[64];
+  int encrypted_data_size;
+};
+
+const WebmEncryptedData kEncryptedFrames[] = {
+  {
+    // plaintext
+    "Original data.", 14,
+    // key_id
+    "\x0\x1\x2\x3\x4\x5\x6\x7\x8\x9\xa\xb\xc\xd\xe\xf"
+    "\x10\x11\x12\x13", 20,
+    // key
+    "\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23", 16,
+    // encrypted_data
+    "\xfb\xe7\x1d\xbb\x4c\x23\xce\xba\xcc\xf8\xda\xc0\xff\xff\xff\xff"

[xhwang, 2012/06/14 19:42:27]

FYI, I am switching to {0x00, 0x11, ...} style for binary array definition:
http://codereview.chromium.org/10534096/diff/2003/media/crypto/aes_decryptor_...

I switched mainly to avoid the "arraysize(array) - 1" hassle and not need to
specify the size all the time (see comment below).

Also, I found this is used more commonly:
http://code.google.com/searchframe#OAMlx_jo-ck/src/crypto/encryptor_unittest....
http://code.google.com/searchframe#OAMlx_jo-ck/src/media/webm/webm_cluster_pa...

[fgalligan1, 2012/07/03 22:00:15]

Done.

+    "\xff\xff\xff\xff\x99\xaa\xff\xb7\x74\x2\x4e\x1c\x75\x3d\xee\xcb"
+    "\x64\xf7", 34
+  },
+  {
+    // plaintext
+    "Changed Original data.", 22,
+    // key_id
+    "\x0\x1\x2\x3\x4\x5\x6\x7\x8\x9\xa\xb\xc\xd\xe\xf"
+    "\x10\x11\x12\x13", 20,
+    // key
+    "\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23", 16,
+    // encrypted_data
+    "\x43\xe4\x78\x7a\x43\xe1\x49\xbb\x44\x38\xdf\xfc\x0\x0\x0\x0"
+    "\x0\x0\x0\x0\xec\x8e\x87\x21\xd3\xb9\x1c\x61\xf6\x5a\x60\xaa"
+    "\x7\xe\x96\xd0\x54\x5d\x35\x9a\x4a\xd3", 42
+  },
+  {
+    // plaintext
+    "Original data.", 14,
+    // key_id
+    "\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30", 13,
+    // key
+    "\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40", 16,
+    // encrypted_data
+    "\xd9\x43\x30\xfd\x82\x77\x62\x4\x8\xc2\x48\x89\x0\x0\x0\x0"
+    "\x0\x0\x0\x1\x48\x5e\x4a\x41\x2a\x8b\xf4\xc6\x47\x54\x90\x34"
+    "\xf4\x8b", 34
+  },
+};
+
+static const int kKeySize = 16;
+static const unsigned char kWrongKey[] = "I'm a wrong key.";
+static const unsigned char kFrame0InvalidHmac[] =
+    "\xfc\xe7\x1d\xbb\x4c\x23\xce\xba\xcc\xf8\xda\xc0\xff\xff\xff\xff"
+    "\xff\xff\xff\xff\x99\xaa\xff\xb7\x74\x2\x4e\x1c\x75\x3d\xee\xcb"
+    "\x64\xf7";
+static const unsigned char kFrame0InvalidIv[] =
+    "\xfb\xe7\x1d\xbb\x4c\x23\xce\xba\xcc\xf8\xda\xc0\x0f\xff\xff\xff"
+    "\xff\xff\xff\xff\x99\xaa\xff\xb7\x74\x2\x4e\x1c\x75\x3d\xee\xcb"
+    "\x64\xf7";
+static const unsigned char kFrame0InvalidData[] =
+    "\xfb\xe7\x1d\xbb\x4c\x23\xce\xba\xcc\xf8\xda\xc0\xff\xff\xff\xff"
+    "\xff\xff\xff\xff\x99\xaa\xff\xb7\x74\x2\x4e\x1c\x75\x3d\xee\xcb"
+    "\x64\xf8";
+
+class HmacAesDecryptorTest : public testing::Test {
+ public:
+  HmacAesDecryptorTest() {}
+
+ protected:
+  scoped_refptr<DecoderBuffer> CreateEncryptedBuffer(const uint8* data,
+                                                     int data_size,
+                                                     const uint8* key_id,
+                                                     int key_id_size) {
+    CHECK_GE(data_size,
+             DecryptConfig::kWebMIntegrityCheckSize + DecryptConfig::kIvSize);
+    scoped_refptr<DecoderBuffer> encrypted_buffer = DecoderBuffer::CopyFrom(
+        data, data_size);
+    CHECK(encrypted_buffer);
+
+    // Every encrypted Block has an HMAC and IV prepended to it. Current WebM
+    // encrypted request for comments specification is here
+    // http://wiki.webmproject.org/encryption/webm-encryption-rfc.
+    uint64 network_iv;
+    memcpy(&network_iv,
+           data + DecryptConfig::kWebMIntegrityCheckSize,
+           sizeof(network_iv));
+    const uint64 iv = base::NetToHost64(network_iv);
+    encrypted_buffer->SetDecryptConfig(
+        scoped_ptr<DecryptConfig>(new DecryptConfig(
+            data, DecryptConfig::kWebMIntegrityCheckSize,
+            iv,
+            key_id, key_id_size)));
+    return encrypted_buffer;
+  }
+
+  void DecryptAndExpectToSucceed(const uint8* data, int data_size,
+                                 const uint8* plain_text,
+                                 int plain_text_size,
+                                 const uint8* key_id, int key_id_size) {

[xhwang, 2012/06/14 19:42:27]

Since data, plain_text and key_id are all arrays and this function is only used
in this test, we can use template to derive array size automatically:

template <int KeyIdSize, int KeySize>
void AddKeyAndExpectToSucceed(const uint8 (&key_id)[KeyIdSize],
                              const uint8 (&key)[KeySize]) {
  decryptor_.AddKey(kClearKeySystem, key, KeySize, key_id, KeyIdSize,
                    session_id_string_);
}

Note that if the arrays are defined using string literal ("\x**"), we have to
use "KeySize - 1". That's another reason I switched to { 0x** } for defining
arrays.

[fgalligan1, 2012/07/03 22:00:15]

I can't use the template function here because it will be the size of the
reserved memory instead of what I initialize the arrays too.

+    scoped_refptr<DecoderBuffer> encrypted_data =
+        CreateEncryptedBuffer(data, data_size, key_id, key_id_size);
+    scoped_refptr<DecoderBuffer> decrypted =
+        decryptor_.Decrypt(encrypted_data);
+    ASSERT_TRUE(decrypted);
+    ASSERT_EQ(plain_text_size, decrypted->GetDataSize());
+    EXPECT_EQ(0, memcmp(plain_text, decrypted->GetData(), plain_text_size));
+  }
+
+  void DecryptAndExpectToFail(const uint8* data, int data_size,
+                              const uint8* plain_text, int plain_text_size,
+                              const uint8* key_id, int key_id_size) {
+    scoped_refptr<DecoderBuffer> encrypted_data =
+        CreateEncryptedBuffer(data, data_size, key_id, key_id_size);
+    scoped_refptr<DecoderBuffer> decrypted =
+        decryptor_.Decrypt(encrypted_data);
+    EXPECT_FALSE(decrypted);
+  }
+
+  HmacAesDecryptor decryptor_;
+};
+
+TEST_F(HmacAesDecryptorTest, NormalDecryption) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToSucceed(frame.encrypted_data,
+                                                    frame.encrypted_data_size,
+                                                    frame.plain_text,
+                                                    frame.plain_text_size,
+                                                    frame.key_id,
+                                                    frame.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, WrongKey) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    kWrongKey, kKeySize);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToFail(frame.encrypted_data,
+                                                 frame.encrypted_data_size,
+                                                 frame.plain_text,
+                                                 frame.plain_text_size,
+                                                 frame.key_id,
+                                                 frame.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, MultipleKeys) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  const WebmEncryptedData& frame2 = kEncryptedFrames[2];
+  decryptor_.AddKey(frame2.key_id, frame2.key_id_size,
+                    frame2.key, frame2.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToSucceed(frame.encrypted_data,
+                                                    frame.encrypted_data_size,
+                                                    frame.plain_text,
+                                                    frame.plain_text_size,
+                                                    frame.key_id,
+                                                    frame.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, KeyReplacement) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    kWrongKey, kKeySize);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToFail(frame.encrypted_data,
+                                                 frame.encrypted_data_size,
+                                                 frame.plain_text,
+                                                 frame.plain_text_size,
+                                                 frame.key_id,
+                                                 frame.key_id_size));
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToSucceed(frame.encrypted_data,
+                                                    frame.encrypted_data_size,
+                                                    frame.plain_text,
+                                                    frame.plain_text_size,
+                                                    frame.key_id,
+                                                    frame.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, MultipleKeysAndFrames) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  const WebmEncryptedData& frame2 = kEncryptedFrames[2];
+  decryptor_.AddKey(frame2.key_id, frame2.key_id_size,
+                    frame2.key, frame2.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToSucceed(frame.encrypted_data,
+                                                    frame.encrypted_data_size,
+                                                    frame.plain_text,
+                                                    frame.plain_text_size,
+                                                    frame.key_id,
+                                                    frame.key_id_size));
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToSucceed(frame2.encrypted_data,
+                                                    frame2.encrypted_data_size,
+                                                    frame2.plain_text,
+                                                    frame2.plain_text_size,
+                                                    frame2.key_id,
+                                                    frame2.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, HmacCheckFailure) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToFail(kFrame0InvalidHmac,
+                                                 frame.encrypted_data_size,
+                                                 frame.plain_text,
+                                                 frame.plain_text_size,
+                                                 frame.key_id,
+                                                 frame.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, IvCheckFailure) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToFail(kFrame0InvalidIv,
+                                                 frame.encrypted_data_size,
+                                                 frame.plain_text,
+                                                 frame.plain_text_size,
+                                                 frame.key_id,
+                                                 frame.key_id_size));
+}
+
+TEST_F(HmacAesDecryptorTest, DataCheckFailure) {
+  const WebmEncryptedData& frame = kEncryptedFrames[0];
+  decryptor_.AddKey(frame.key_id, frame.key_id_size,
+                    frame.key, frame.key_size);
+  ASSERT_NO_FATAL_FAILURE(DecryptAndExpectToFail(kFrame0InvalidData,
+                                                 frame.encrypted_data_size,
+                                                 frame.plain_text,
+                                                 frame.plain_text_size,
+                                                 frame.key_id,
+                                                 frame.key_id_size));
+}
+
+}  // media