From 6d14cb50509908f9a6c70065d6bf07a6f33a17d3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20V=C3=B6lcker?= <65532189+bjornvolcker@users.noreply.github.com> Date: Mon, 9 Mar 2026 16:14:30 +0100 Subject: [PATCH 1/3] Remove Arbitrary Data TLV The possibility to add arbitrary data to a Media Signing SEI generates an attack vector. Therefore, that specific type is removed from the specification. If a vendor would like to add some metadata and have it signed, that data shall be put in a separate SEI of type user data unregistered with a different UUID (44959c31-e3f3-4aeb-8b4c-5e3a865801fc). --- doc/MediaSigning.xml | 30 ++++++++---------------------- 1 file changed, 8 insertions(+), 22 deletions(-) diff --git a/doc/MediaSigning.xml b/doc/MediaSigning.xml index a3f8b096f..0b5c33728 100644 --- a/doc/MediaSigning.xml +++ b/doc/MediaSigning.xml @@ -283,6 +283,8 @@ Picture NAL Units, that is, slices of IDR-, P- and B-frames. All SEI frames generated according to this specification, if not including a signature. + SEI frames of type user data unregistered with UUID + 44959c31-e3f3-4aeb-8b4c-5e3a865801fc shall be hashed like a VCL NAL Unit. Every GOP must be associated with at least one SEI frame @@ -905,18 +907,6 @@ signatures. - - - Arbitrary data - - - 7 - - - Optional - - Additional data can be put here as a vendor specific blob. - @@ -1122,16 +1112,6 @@ -
- Arbitrary data - This optional field contains Abritrary data that the device vendor want to be - included. There is no guarantee that the data is reasonable or readable by - anyone not previously knowledgeable in the area. - The data tag can be added to any SEI described in - this specification or to a SEI of its own. - This tag can be useful to add vendor or device specific information and get it - signed. -
Low Bitrate Mode @@ -1147,6 +1127,12 @@ correctly verified (partial) GOP hash, all NAL Units now have to be present and correct.
+
+ How a device can add and secure vendor specifc metadata to a stream + Use a SEI of type user data unregistered with UUID + 44959c31-e3f3-4aeb-8b4c-5e3a865801fc. This NAL Unit shall be hashed + like a VCL NAL Unit. +
How to generate the first certificate SEI From d7e16f159a555d1a768ddb0f26b5975b5f72c552 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20V=C3=B6lcker?= Date: Tue, 24 Mar 2026 12:39:04 +0100 Subject: [PATCH 2/3] Revert "Remove Arbitrary Data TLV" This reverts commit 6d14cb50509908f9a6c70065d6bf07a6f33a17d3. --- doc/MediaSigning.xml | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) diff --git a/doc/MediaSigning.xml b/doc/MediaSigning.xml index 0b5c33728..a3f8b096f 100644 --- a/doc/MediaSigning.xml +++ b/doc/MediaSigning.xml @@ -283,8 +283,6 @@ Picture NAL Units, that is, slices of IDR-, P- and B-frames. All SEI frames generated according to this specification, if not including a signature. - SEI frames of type user data unregistered with UUID - 44959c31-e3f3-4aeb-8b4c-5e3a865801fc shall be hashed like a VCL NAL Unit. Every GOP must be associated with at least one SEI frame @@ -907,6 +905,18 @@ signatures. + + + Arbitrary data + + + 7 + + + Optional + + Additional data can be put here as a vendor specific blob. + @@ -1112,6 +1122,16 @@
+
+ Arbitrary data + This optional field contains Abritrary data that the device vendor want to be + included. There is no guarantee that the data is reasonable or readable by + anyone not previously knowledgeable in the area. + The data tag can be added to any SEI described in + this specification or to a SEI of its own. + This tag can be useful to add vendor or device specific information and get it + signed. +
Low Bitrate Mode @@ -1127,12 +1147,6 @@ correctly verified (partial) GOP hash, all NAL Units now have to be present and correct.
-
- How a device can add and secure vendor specifc metadata to a stream - Use a SEI of type user data unregistered with UUID - 44959c31-e3f3-4aeb-8b4c-5e3a865801fc. This NAL Unit shall be hashed - like a VCL NAL Unit. -
How to generate the first certificate SEI From 847800c3f79e6c4e58533415a1b18cd3274720f1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20V=C3=B6lcker?= Date: Tue, 24 Mar 2026 13:30:02 +0100 Subject: [PATCH 3/3] Clarified that Arbitrary Data tag can only be used alone --- doc/MediaSigning.xml | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/doc/MediaSigning.xml b/doc/MediaSigning.xml index a3f8b096f..ad40c0d54 100644 --- a/doc/MediaSigning.xml +++ b/doc/MediaSigning.xml @@ -1124,11 +1124,12 @@
Arbitrary data - This optional field contains Abritrary data that the device vendor want to be - included. There is no guarantee that the data is reasonable or readable by - anyone not previously knowledgeable in the area. - The data tag can be added to any SEI described in - this specification or to a SEI of its own. + This optional field contains Abritrary data that a device can add to the stream. + The data is not used by Media Signing and interpretations is left to the vendor. + The data tag shall be added to a separate unsigned SEI, + that is, there shall be no other tags present in the SEI when this tag is present. + Validation shall be marked as "Not authentic" if this tag is present together with other + tags. This tag can be useful to add vendor or device specific information and get it signed.
@@ -1147,6 +1148,12 @@ correctly verified (partial) GOP hash, all NAL Units now have to be present and correct. +
+ How a device can add and secure vendor specifc metadata to a stream + Generate a Media Signing SEI with only an Arbitrary Data tag; See Section + . This NAL Unit will automatically be hashed + and thereby signed. +
How to generate the first certificate SEI