Allow specifying protection pattern for pattern encryption

Added --crypt_byte_block, --skip_byte_block to allow users to specify
protection pattern other than 1:9 for pattern based encryption scheme,
e.g. cbcs and cens.

Closes #710.
b/147307451

Change-Id: I9f64a7639170c737f138572689b28d17286325c7

docs/source/options/general_encryption_options.rst

@@ -6,6 +6,24 @@ General encryption options
     Specify a protection scheme, 'cenc' or 'cbc1' or pattern-based protection
     schemes 'cens' or 'cbcs'.
 
+--crypt_byte_block
+
+    Specify the count of the encrypted blocks in the protection pattern, where
+    block is of size 16-bytes.
+
+    There are three common patterns (crypt_byte_block:skip_byte_block):
+    1:9 (default), 5:5, 10:0.
+
+    Apply to video streams with 'cbcs' and 'cens' protection schemes only;
+    ignored otherwise.
+
+--skip_byte_block
+
+    Specify the count of the unencrypted blocks in the protection pattern.
+
+    Apply to video streams with 'cbcs' and 'cens' protection schemes only;
+    ignored otherwise.
+
 --vp9_subsample_encryption, --novp9_subsample_encryption
 
     Enable / disable VP9 subsample encryption. Enabled by default.

packager/app/crypto_flags.cc

@@ -12,4 +12,33 @@ DEFINE_string(protection_scheme,
               "cenc",
               "Specify a protection scheme, 'cenc' or 'cbc1' or pattern-based "
               "protection schemes 'cens' or 'cbcs'.");
+DEFINE_int32(
+    crypt_byte_block,
+    1,
+    "Specify the count of the encrypted blocks in the protection pattern, "
+    "where block is of size 16-bytes. There are three common "
+    "patterns (crypt_byte_block:skip_byte_block): 1:9 (default), 5:5, 10:0. "
+    "Apply to video streams with 'cbcs' and 'cens' protection schemes only; "
+    "ignored otherwise.");
+DEFINE_int32(
+    skip_byte_block,
+    9,
+    "Specify the count of the unencrypted blocks in the protection pattern. "
+    "Apply to video streams with 'cbcs' and 'cens' protection schemes only; "
+    "ignored otherwise.");
 DEFINE_bool(vp9_subsample_encryption, true, "Enable VP9 subsample encryption.");
+
+bool ValueNotGreaterThanTen(const char* flagname, int32_t value) {
+  if (value > 10) {
+    fprintf(stderr, "ERROR: %s must not be greater than 10.\n", flagname);
+    return false;
+  }
+  if (value < 0) {
+    fprintf(stderr, "ERROR: %s must be non-negative.\n", flagname);
+    return false;
+  }
+  return true;
+}
+
+DEFINE_validator(crypt_byte_block, &ValueNotGreaterThanTen);
+DEFINE_validator(skip_byte_block, &ValueNotGreaterThanTen);

packager/app/crypto_flags.h

@@ -13,6 +13,8 @@
 #include <gflags/gflags.h>
 
 DECLARE_string(protection_scheme);
+DECLARE_int32(crypt_byte_block);
+DECLARE_int32(skip_byte_block);
 DECLARE_bool(vp9_subsample_encryption);
 
 #endif  // PACKAGER_APP_CRYPTO_FLAGS_H_

packager/app/packager_main.cc

@@ -343,6 +343,9 @@ base::Optional<PackagingParams> GetPackagingParams() {
     encryption_params.clear_lead_in_seconds = FLAGS_clear_lead;
     if (!GetProtectionScheme(&encryption_params.protection_scheme))
       return base::nullopt;
+    encryption_params.crypt_byte_block = FLAGS_crypt_byte_block;
+    encryption_params.skip_byte_block = FLAGS_skip_byte_block;
+
     encryption_params.crypto_period_duration_in_seconds =
         FLAGS_crypto_period_duration;
     encryption_params.vp9_subsample_encryption = FLAGS_vp9_subsample_encryption;

packager/app/test/packager_test.py

@@ -417,6 +417,8 @@ class PackagerAppTest(unittest.TestCase):
                 encryption=False,
                 protection_systems=None,
                 protection_scheme=None,
+                crypt_byte_block=None,
+                skip_byte_block=None,
                 vp9_subsample_encryption=True,
                 decryption=False,
                 random_iv=False,
@@ -469,6 +471,11 @@ class PackagerAppTest(unittest.TestCase):
 
     if protection_scheme:
       flags += ['--protection_scheme', protection_scheme]
+      if crypt_byte_block is not None and skip_byte_block is not None:
+        flags += [
+            '--crypt_byte_block={0}'.format(crypt_byte_block),
+            '--skip_byte_block={0}'.format(skip_byte_block)
+        ]
     if not vp9_subsample_encryption:
       flags += ['--vp9_subsample_encryption=false']
 
@@ -1042,6 +1049,18 @@ class PackagerFunctionalTest(PackagerAppTest):
             encryption=True, protection_scheme='cbcs', output_dash=True))
     self._CheckTestResults('encryption-cbcs', verify_decryption=True)
 
+  def testEncryptionCbcsWithFullProtection(self):
+    self.assertPackageSuccess(
+        self._GetStreams(['audio', 'video']),
+        self._GetFlags(
+            encryption=True,
+            protection_scheme='cbcs',
+            crypt_byte_block=10,
+            skip_byte_block=0,
+            output_dash=True))
+    self._CheckTestResults(
+        'encryption-cbcs-with-full-protection', verify_decryption=True)
+
   def testEncryptionAndAdCues(self):
     self.assertPackageSuccess(
         self._GetStreams(['audio', 'video'], hls=True),
@@ -1774,6 +1793,17 @@ class PackagerCommandParsingTest(PackagerAppTest):
     # Expect the test to fail but we do not expect a crash.
     self.assertEqual(packaging_result, 1)
 
+  def testIncorrectEncryptionPattern(self):
+    packaging_result = self.packager.Package(
+        self._GetStreams(['audio', 'video']),
+        self._GetFlags(
+            encryption=True,
+            protection_scheme='cbcs',
+            crypt_byte_block=12,
+            skip_byte_block=13,
+            output_dash=True))
+    self.assertEqual(packaging_result, 1)
+
 
 if __name__ == '__main__':
   unittest.main()

packager/app/test/testdata/encryption-cbcs-with-full-protection/output.mpd

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--Generated with https://github.com/google/shaka-packager version <tag>-<hash>-<test>-->
+<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:mpeg:dash:schema:mpd:2011 DASH-MPD.xsd" xmlns:cenc="urn:mpeg:cenc:2013" profiles="urn:mpeg:dash:profile:isoff-on-demand:2011" minBufferTime="PT2S" type="static" mediaPresentationDuration="PT2.7360665798187256S">
+  <Period id="0">
+    <AdaptationSet id="0" contentType="video" width="640" height="360" frameRate="30000/1001" subsegmentAlignment="true" par="16:9">
+      <ContentProtection value="cbcs" schemeIdUri="urn:mpeg:dash:mp4protection:2011" cenc:default_KID="31323334-3536-3738-3930-313233343536"/>
+      <ContentProtection schemeIdUri="urn:uuid:1077efec-c0b2-4d02-ace3-3c1e52e2fb4b">
+        <cenc:pssh>AAAANHBzc2gBAAAAEHfv7MCyTQKs4zweUuL7SwAAAAExMjM0NTY3ODkwMTIzNDU2AAAAAA==</cenc:pssh>
+      </ContentProtection>
+      <Representation id="0" bandwidth="975825" codecs="avc1.64001e" mimeType="video/mp4" sar="1:1">
+        <BaseURL>bear-640x360-video.mp4</BaseURL>
+        <SegmentBase indexRange="1136-1203" timescale="30000">
+          <Initialization range="0-1135"/>
+        </SegmentBase>
+      </Representation>
+    </AdaptationSet>
+    <AdaptationSet id="1" contentType="audio" subsegmentAlignment="true">
+      <ContentProtection value="cbcs" schemeIdUri="urn:mpeg:dash:mp4protection:2011" cenc:default_KID="31323334-3536-3738-3930-313233343536"/>
+      <ContentProtection schemeIdUri="urn:uuid:1077efec-c0b2-4d02-ace3-3c1e52e2fb4b">
+        <cenc:pssh>AAAANHBzc2gBAAAAEHfv7MCyTQKs4zweUuL7SwAAAAExMjM0NTY3ODkwMTIzNDU2AAAAAA==</cenc:pssh>
+      </ContentProtection>
+      <Representation id="1" bandwidth="133334" codecs="mp4a.40.2" mimeType="audio/mp4" audioSamplingRate="44100">
+        <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
+        <BaseURL>bear-640x360-audio.mp4</BaseURL>
+        <SegmentBase indexRange="1012-1079" timescale="44100">
+          <Initialization range="0-1011"/>
+        </SegmentBase>
+      </Representation>
+    </AdaptationSet>
+  </Period>
+</MPD>

packager/media/crypto/encryption_handler.cc

@@ -253,9 +253,8 @@ Status EncryptionHandler::ProcessMediaSample(
 void EncryptionHandler::SetupProtectionPattern(StreamType stream_type) {
   if (stream_type == kStreamVideo &&
       IsPatternEncryptionScheme(protection_scheme_)) {
-    // Use 1:9 pattern.
-    crypt_byte_block_ = 1u;
-    skip_byte_block_ = 9u;
+    crypt_byte_block_ = encryption_params_.crypt_byte_block;
+    skip_byte_block_ = encryption_params_.skip_byte_block;
   } else {
     // Audio stream in pattern encryption scheme does not use pattern; it uses
     // whole-block full sample encryption instead. Non-pattern encryption does

packager/media/public/crypto_params.h

@@ -134,6 +134,16 @@ struct EncryptionParams {
   static constexpr uint32_t kProtectionSchemeCens = 0x63656E73;
   static constexpr uint32_t kProtectionSchemeCbcs = 0x63626373;
   uint32_t protection_scheme = kProtectionSchemeCenc;
+  /// The count of the encrypted blocks in the protection pattern, where each
+  /// block is of size 16-bytes. There are three common patterns
+  /// (crypt_byte_block:skip_byte_block): 1:9 (default), 5:5, 10:0.
+  /// Applies to video streams with "cbcs" and "cens" protection schemes only;
+  /// Ignored otherwise.
+  uint8_t crypt_byte_block = 1;
+  /// The count of the unencrypted blocks in the protection pattern.
+  /// Applies to video streams with "cbcs" and "cens" protection schemes only;
+  /// Ignored otherwise.
+  uint8_t skip_byte_block = 9;
   /// Crypto period duration in seconds. A positive value means key rotation is
   /// enabled, the key provider must support key rotation in this case.
   static constexpr double kNoKeyRotation = 0;