Shriramana, On Thursday 18 August 2005 19:29, Shriramana Sharma wrote:
On 8/19/05, Randall R Schulz
wrote: different contents) and still yield the same CD or DVD. One obvious possibility would be a time-stamp that describes the .iso file or its creation but not its logical content.
Randall, so are you saying that since Terry and I created the image at different times we can have different md5sums and still the same content, with just the file timestamps being different?
Well, that's certainly true, thought not exactly what I was saying. Since file modes and modification, change or access times, as well as every last other attribute that is recorded on a CD or DVD, must be recorded in the .iso image for that disck, changing any of those attributes for any file out of the entirety of those on the disc in question will change the checksum for the .iso image built from those files. But what I was hypothesizing was that there might be values in a .iso file that did not contribute to the contents of the disc written from that .iso (such as, e.g., a timestamp telling when the .iso was generated). In that case, you'd could have two different .iso files with different checksums even though the resulting discs made from them would be identical. But I should emphasize that I do not know anything about the details of the .iso format, so this is just a hunch, not a fact.
How, then, can I be sure that Terry and I got the exact same *content* (forget timestamps) that Terry got?
I don't know. I don't know that it's possible (or that it's not). Sorry.
(Note: I still haven't burned the image to DVD, since I was waiting for Terry's md5 report.)
Randall Schulz