如何使用 Bento4 sdk 或 FFmpeg 解密加密的 MPEG CENC OMA DCF

如何解决如何使用 Bento4 sdk 或 FFmpeg 解密加密的 MPEG CENC OMA DCF

我相信我有一个在 CENC 中加密的文件，并且我现在尝试使用来自 Bento4 mp4decrypt 工具的 mp4decrypt 对其进行解密超过几个月，但相信我，我只是不知道如何。这是 mp4info --verbose

MP4INFO 详细

C:\Users\Vector\Desktop\Bento4\Bento4-SDK-1-6-0-637.x86_64-microsoft-win32\bin>mp4info --verbose C:\Users\Vector\Desktop\Bento4\IrokoBeautyandTheBeast\Movies\fmp4_480p_450000.mp4
File:
  major brand:      iso6
  minor version:    1
  compatible brand: mp42
  compatible brand: dash
  compatible brand: msdh
  compatible brand: msix
  compatible brand: iso6
  compatible brand: avc1
  compatible brand: isom
  fast start:       yes

Movie:
  duration:   0 ms
  time scale: 12800
  fragments:  yes

Found 1 Tracks
Track 1:
  flags:        7 ENABLED IN-MOVIE IN-PREVIEW
  id:           1
  type:         Video
  duration: 0 ms
  language: eng
  media:
    sample count: 0
    timescale:    12800
    duration:     0 (media timescale units)
    duration:     0 (ms)
    bitrate (computed): 449.893 Kbps
    sample count with fragments: 191503
    duration with fragments:     98049536
    duration with fragments:     7660120 (ms)
  display width:  854.000000
  display height: 480.000000
  Sample Description 0
    [ENCRYPTED]
      Coding:         encv
      Scheme Type:    cenc
      Scheme Version: 65536
      Scheme URI:
    Protection System Details:
    [schi] size=8+32
      [tenc] size=12+20
        default_isProtected = 1
        default_Per_Sample_IV_Size = 8
        default_KID = [71 95 60 47 eb fe 4c ed 9d 7c 29 7c 26 da a9 d7]
    Bytes: 000000000000000100000000000000000000000000000000035601e000480000004800000000000000010a41564320436f64696e670000000000000000000000000000000000000000000018ffff00000031617663430142c01effe100196742c01ed900d83de6f011000003000100000300320f162e4801000568cb852c800000005073696e660000000c66726d6161766331000000147363686d0000000063656e630001000000000028736368690000002074656e63000000000000010871956047ebfe4ced9d7c297c26daa9d7
    Coding:      avc1 (H.264)
    Width:       854
    Height:      480
    Depth:       24
    AVC Profile:          66 (Baseline)
    AVC Profile Compat:   c0
    AVC Level:            30
    AVC NALU Length Size: 4
    AVC SPS: [6742c01ed900d83de6f011000003000100000300320f162e48]
    AVC PPS: [68cb852c80]
    Codecs String: avc1.42C01E

C:\Users\Vector\Desktop\Bento4\Bento4-SDK-1-6-0-637.x86_64-microsoft-win32\bin>

我可以访问的内容：

(1) AUdio AND VIDEO FILES .mp4 which contains the encrypted content for the Apk data files
(2) MANIFEST.mpd also from the apk data files
(3) oma folder

这是受保护文件的 gd 链接 https://drive.google.com/drive/folders/1nQOnOs6oxU-KKZe67ePfkj_adGJhyj9A?usp=sharing 我相信该文件是 OMA DCF/PDCF 文件

ProtectedROS.xml 文件

<roap:protectedRO xmlns:roap="urn:oma:bac:dldrm:roap-1.0">
        <roap:ro id="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" stateful="true" version="1.1">
            <riID>
                <keyIdentifier xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" algorithm="http://www.w3.org/2000/09/xmldsig#sha1" xsi:type="roap:X509SPKIHash">
                    <hash>od6D5p9bah7N0kyo9JrscpOdK2I=</hash>
                </keyIdentifier>
            </riID>
            <rights xmlns:o-ex="http://odrl.net/1.1/ODRL-EX" o-ex:id="REL0">
                <o-ex:context>
                    <o-dd:version xmlns:o-dd="http://odrl.net/1.1/ODRL-DD">2.1</o-dd:version>
                    <o-dd:uid xmlns:o-dd="http://odrl.net/1.1/ODRL-DD">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</o-dd:uid>
                </o-ex:context>
                <o-ex:agreement>
                    <o-ex:asset o-ex:id="Audio-Video Key 71956047ebfe4ced9d7c297c26daa9d7">
                        <o-ex:context>
                            <o-dd:uid xmlns:o-dd="http://odrl.net/1.1/ODRL-DD">irokotv:content:15473</o-dd:uid>
                        </o-ex:context>
                        <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                            <xenc:EncryptedKey xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
                                <xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#kw-aes128"></xenc:EncryptionMethod>
                                <ds:KeyInfo>
                                    <ds:RetrievalMethod URI="#K_MAC_and_K_REK0"></ds:RetrievalMethod>
                                </ds:KeyInfo>
                                <xenc:CipherData>
                                    <xenc:CipherValue>bcua8iKZzPKucfcfUwJFf1+Ha9qOTh+k</xenc:CipherValue>
                                </xenc:CipherData>
                            </xenc:EncryptedKey>
                        </ds:KeyInfo>
                    </o-ex:asset>
                    <o-ex:permission>
                        <o-dd:play xmlns:o-dd="http://odrl.net/1.1/ODRL-DD">
                            <o-ex:constraint>
                                <o-dd:datetime>
                                    <o-dd:end>2021-03-25T18:46:16Z</o-dd:end>
                                </o-dd:datetime>
                                <o-dd:interval>P30D</o-dd:interval>
                                <oma-dd:system xmlns:oma-dd="http://www.openmobilealliance.com/oma-dd">
                                    <o-ex:context>
                                        <o-dd:uid>urn:oma:drms:org-cmla:std-def-analog-outputs</o-dd:uid>
                                    </o-ex:context>
                                    <o-ex:context>
                                        <o-dd:uid>urn:oma:drms:org-cmla:dtcp-ip</o-dd:uid>
                                    </o-ex:context>
                                    <o-ex:context>
                                        <o-dd:uid>urn:oma:drms:org-cmla:hdcp</o-dd:uid>
                                    </o-ex:context>
                                </oma-dd:system>
                            </o-ex:constraint>
                        </o-dd:play>
                    </o-ex:permission>
                </o-ex:agreement>
            </rights>
            <timeStamp>2021-02-23T18:46:15Z</timeStamp>
            <encKey Id="K_MAC_and_K_REK0">
                <xenc:EncryptionMethod xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" Algorithm="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-1#rSAEs-kem-kdf2-kw-aes128"></xenc:EncryptionMethod>
                <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                    <roap:X509SPKIHash algorithm="http://www.w3.org/2000/09/xmldsig#sha1">
                        <hash>jgQbmMVpFoZpu7X9CElrymPvO5U=</hash>
                    </roap:X509SPKIHash>
                </ds:KeyInfo>
                <xenc:CipherData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
                    <xenc:CipherValue>TNz5JLn7BXfL+DMC7nZD9vM5Jo70tZrbAcZC4a1d6QuKnOITwNOS+A/oEaiqofJFqDajzv9c1klw8HIW4gw5167RHF7krXD14OtbJQdP7eA0Xi8TwQtrxATVd7G0QQBcvUfdrqRmgmgW8fhaTv6NQsHYPkQsv8yswhKKaboa6MQ4agTBTswc94y7OFEFweI1EFBZGAnmvs8jrilx6U4t6bOFFh9Q25NGMHmv15EuzKHvhjUbLaVG1sdvwkA4IVAXsrTPmxhhCRgHtnG7q7SRtF2WpB5tAOHtP1bXaqktfWXrI8QLm7etsJ0V0bQkzyfY6F9PTmUtR8CJueKa07TnOEmSBKf/y6qguZQm2yC5qQLwWTpNxA7rm4qO72xw1mnYn4zaRrAsYdA=</xenc:CipherValue>
                </xenc:CipherData>
            </encKey>
        </roap:ro>
        <mac>
            <ds:SignedInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"></ds:CanonicalizationMethod>
                <ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"></ds:SignatureMethod>
                <ds:Reference URI="#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">
                    <ds:Transforms>
                        <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"></ds:Transform>
                    </ds:Transforms>
                    <ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"></ds:DigestMethod>
                    <ds:DigestValue>6eq2dQs3WK/LddLVkgij2t3kX+I=</ds:DigestValue>
                </ds:Reference>
            </ds:SignedInfo>
            <ds:SignatureValue xmlns:ds="http://www.w3.org/2000/09/xmldsig#">ckMnemCWwJaoi+aqgwln9/TWIuE=</ds:SignatureValue>
            <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                <ds:RetrievalMethod URI="#K_MAC_and_K_REK0"></ds:RetrievalMethod>
            </ds:KeyInfo>
        </mac>
    </roap:protectedRO>
</storedRightsObjects>

是否可以将音频和视频都解密为可播放的非加密文件？从在线信息来看，我相信使用上面提供的 xml 我可以获得 CEK，如果不是缺少什么？

解决方法

有两个不同的问题在起作用：

CENC（通用加密）
DRM（数字版权管理）

CENC 独立于供应商。所以加密一次完成，它是一个标准。密钥是秘密的，通常不会以明文形式存储或传输。

DRM 是特定于供应商的，指定了密钥的交换方式。

CENC 和 DRM 都不容易破解。

有关如何获取密钥 (DRM) 的说明存储在 pssh 盒中，并传递给您计算机的安全计算硬件，然后进行安全密钥交换。

在您的情况下，安全计算硬件将联系 https://lic.drmtoday.com/license-proxy-headerauth/drmtoday/RightsManager.asmx 并使用您登录后获得的令牌索取 ID 为 f01b6f9535f93e48b82138ae52633f4c 的密钥。

您可以使用多个 DRM 系统。例如 Widevine (Google) 或 PlayReady (Microsoft)

如果您拥有最初用于加密内容的密钥，则您只能解密流。查看您捕获的许可请求 - 我正在收集使用 Google 的 Widevine DRM 系统。

您可以假设 Google 使用的是“最先进的”密钥交换方法，您无法通过右键单击浏览器窗口或浏览器开发工具来破解该方法。

我对 Widevine 的内部运作一无所知，但我猜他们会这样做：https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange

GPAC 会解密，但您必须提供密钥及其密钥 ID https://github.com/gpac/gpac/wiki/Common-Encryption