Timeline for Large file validation on an embedded system through hash and encryption
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
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| Nov 24, 2014 at 5:34 | comment | added | fgrieu♦ | @McMurrich: what you described in above comment is a simple hash tree. As pointed by Richie Frame, it will not detect alteration of a block that was not supposed to have changed, but did (with no change of the stored hash, remaining at its former, original value, no longer matching the file content). I can't tell if that's a problem in your threat model: on one hand you trust the embedded system (when it accesses the data and compute hashes), and on the other you do not (when it comes to not changing this data). | |
| Oct 29, 2014 at 3:28 | comment | added | Martin Thomson | Yep. The only caveat there is if your patches adjust the size of a block. If you want to continue using the hashes for other blocks, you will have to track how that change affects the block boundaries. | |
| Oct 27, 2014 at 17:47 | comment | added | McMurrich | Thanks for the suggestions. My understanding is as follows: Consider using multiple hashes for fixed block sizes. When applying updates, just re-calculate the hashes for those blocks that have been impacted with the update. Have a hash for the collection of hashes to verify the entire large file hasn't changed. Now, everytime the data is loaded, then just verify the hash of hashes to ensure the file hasn't been tampered with. Did I get that right? | |
| Oct 26, 2014 at 22:09 | comment | added | Martin Thomson | You might avoid the need to check every time if you can be sure that the file hasn't been tampered with since you last checked. That's a fairly common assumption. | |
| Oct 25, 2014 at 3:39 | comment | added | Richie Frame | delta updates will not help him if he needs to verify the entire file everytime the application is launched, but it will definitely make updating the program faster | |
| Oct 25, 2014 at 2:40 | review | First posts | |||
| Oct 26, 2014 at 9:00 | |||||
| Oct 25, 2014 at 2:39 | history | answered | Martin Thomson | CC BY-SA 3.0 |