Timeline for Is it possible to make a video that is provably non-manipulated?
Current License: CC BY-SA 4.0
20 events
| when toggle format | what | by | license | comment | |
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| May 21, 2021 at 9:45 | comment | added | Joseph Tanenbaum | The problem of pre-recorded video is simple to solve: At the start of the exam a code is distributed to all students, which they have to clearly show to all cameras. Combined with the attestation (by Blockchain or other means) you now prevent pre-recording as well as (post-) editing | |
| Jan 12, 2021 at 19:17 | comment | added | defalt | 10 seconds of frames should be hashed only when the recorder is done writing frames into a file because what camera captures is always different from what is encoded in video format. | |
| Jan 12, 2021 at 0:08 | comment | added | Charles Duffy | @FedericoPoloni, ...modified webcam driver? Why bother, when there's no shortage of off-the-shelf equipment that'll read HDMI input and present as a webcam? | |
| Jan 11, 2021 at 21:09 | comment | added | paulj | The streamed video could include a unique code being generated every five minutes from central server. e.g. Verifying when the recording occurred. | |
| Jan 11, 2021 at 19:06 | comment | added | svavil | Relevant XKCD | |
| Jan 11, 2021 at 9:46 | comment | added | Jon Bentley | @nobody Yes, and I agree, but those are separate points. I was responding specifically to the idea of prerecording. | |
| Jan 11, 2021 at 8:46 | comment | added | Erel Segal-Halevi | While everything can be manipulated with sufficient effort, it seems this idea makes it much harrder. Thanks! | |
| Jan 11, 2021 at 8:43 | vote | accept | Erel Segal-Halevi | ||
| Jan 11, 2021 at 8:45 | |||||
| Jan 11, 2021 at 8:27 | comment | added | nobody | @JonBentley See reed's answer below. The video could, at least in theory, be modified in real time to include the screen with the exam. Also as reed's answer points out, cheating at exams is possible even with a genuine video. Never underestimate the creativity of students determined to cheat. | |
| Jan 10, 2021 at 23:37 | comment | added | blankip | If the student is in a security, crypto or some general IT class, I would leave them time to edit and resend stream, I mean that deserves an A at college level. | |
| Jan 10, 2021 at 20:22 | comment | added | Jon Bentley | @nobody That's not possible if the recording requirements are properly thought through. The OP's scenario involves (among other things) the ability to prove to the examiner that you wrote the exam yourself. In order to achieve that the camera needs to be angled such that at a minimum the exam is legible on the screen. Otherwise the cheater could be doing something unrelated while an accomplice is in another room doing the exam for him. With that assumption a pre-recording is impossible because the exam content would not be known in advance. | |
| Jan 10, 2021 at 13:59 | comment | added | Federico Poloni | In theory, the video could be edited in real-time. With a modified webcam driver, I could press a button and replace the real image with a pre-recorded one of me sitting at a table, blending the two so that they merge without a visible cut. | |
| Jan 10, 2021 at 12:23 | comment | added | Annonymus | The video presumably includes the exam that the student is writing. As such the content of the video is proof that it has not been pre-registered, unless the student had access to the exam questions ahead of time, in which case the entire point of the video is moot. This proof can only be exhibited by publishing the content of the video rather than its hashes, but the question specified such a scenario in case of suspicion of cheating anyway, so this must be considered acceptable. | |
| Jan 10, 2021 at 8:40 | comment | added | Esa Jokinen | This would be a proof that the video existed at a specific time. However, it doesn't prove the video wasn't recorded beforehand and just published or streamed at that time. | |
| Jan 10, 2021 at 8:14 | comment | added | nobody | One possible way to cheat here would be that the student prerecords a video and streams that video (or its hashes) instead of a realtime video. | |
| Jan 9, 2021 at 23:22 | comment | added | Mike Ounsworth | @ErelSegal-Halevi I updated my answer to include the new information you provided in comments. | |
| Jan 9, 2021 at 23:22 | history | edited | Mike Ounsworth | CC BY-SA 4.0 |
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| Jan 9, 2021 at 22:41 | comment | added | Erel Segal-Halevi | The students here do not like the fact that their video is kept in a third-party server. But the idea of storing the hash in a bitcoin transaction sounds very interesting. | |
| Jan 9, 2021 at 21:50 | comment | added | mti2935 | +1. As I was reading the question, the idea of provable timestamping was the first thing that came to mind. For timestamping without relying on a trusted third party, take a hash of the video, and store the hash in a bitcoin transaction. | |
| Jan 9, 2021 at 21:42 | history | answered | Mike Ounsworth | CC BY-SA 4.0 |