In another thread I downloaded & re-encoded a file & attempted to provide it to someone else who needed it. I intended to allow the download only for those who had obtained the original file (so as to avoid being accused of allowing piracy). The way I attempted to do this was download a CRC program & generate the CRC of the file I downloaded. Then if the end user could match that CRC they could download the file.
Something I failed to account for, however, is that the timestamp on the files was different... I've downloaded it three times & generated three different CRC's. It would appear that the creation, accessed, and modified info makes a difference in CRC creation.
If that is the case, how can companies use CRC's to ensure that their products have been downloaded successfully? Obviously this info can be stored in an archived file format (ZIP, TAR, etc.), but what if the archived file is suspected to be corrupt? Also, where/how are the time/date stamps stored? I'd never given it much thought, I always assumed they were stored in the allocation table. I now think this is incorrect since two otherwise identical files created at different times have different CRC's.
[EDIT]I just downloaded it a third time, this time the CRC I got matches one provided to me by another user here... All the files I have play fine, but they all have different CRC's. Perhaps they have multiple servers hosting the file (load balancing? If this is the case then I feel much better.[/EDIT]
Such a basic thing, I feel like a moron.
Viper GTS
Something I failed to account for, however, is that the timestamp on the files was different... I've downloaded it three times & generated three different CRC's. It would appear that the creation, accessed, and modified info makes a difference in CRC creation.
If that is the case, how can companies use CRC's to ensure that their products have been downloaded successfully? Obviously this info can be stored in an archived file format (ZIP, TAR, etc.), but what if the archived file is suspected to be corrupt? Also, where/how are the time/date stamps stored? I'd never given it much thought, I always assumed they were stored in the allocation table. I now think this is incorrect since two otherwise identical files created at different times have different CRC's.
[EDIT]I just downloaded it a third time, this time the CRC I got matches one provided to me by another user here... All the files I have play fine, but they all have different CRC's. Perhaps they have multiple servers hosting the file (load balancing? If this is the case then I feel much better.[/EDIT]
Such a basic thing, I feel like a moron.
Viper GTS
