comment on

My comment is OT, but still ...

I really wonder why one wants to calculate a CRC-32 value on only the text portion of the file.

To me it seems a totally wrong application of CRC-32. As you know, CRC-32 is only useful to detect "bursty" type of errors in files (say linenoise in a modem transmission or hard-disk transmission errors), but then you have to look at the whole file. Only looking at the non-tag parts serves no purpose. You could have all the text OK, but the tags totally goofed-up and you would never know as the CRC-32 would still match.

Perhaps they use the CRC-32 as some kind of cryptographic check on the text data in the file (to see it has not been tampered with), but due to the trivially easy way to calculate a CRC-32, you can change the content and add a few bytes somewhere in the file which would make the CRC-32 match again.

As said above, it only "protects" against random, bursty type of changes but for that you need to look at the transmitted file as a whole. So, my question remains: Why?

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

In reply to Re: XML Tags Stripping & Calculating checksum on it by CountZero
in thread XML Tags Stripping & Calculating checksum on it by harishnuti

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