c# - SHA-1 Hash of uploaded xls file always different, With csv file hashing works -


i got following problem. upload csv , excel files via wcf service. hash calculation work csv files. xls files different value every upload.

hash calculation:

            using (filestream file = new filestream(datei.fullname, filemode.open))             {                 var sha1 = new sha1cryptoserviceprovider();                 byte[] retval = sha1.computehash(file);                 var sb = new stringbuilder();                 foreach (var b in retval)                     sb.append(b.tostring("x2"));                  return sb.tostring();             } 

does know problem might located? problem binary xls file format?

any appreciated.

marius

i suspect file actually different each time. that's easy enough check though - there various free tools around perform checksums/hashes. pick sha1 , compare own results, or use md5 tool etc.

try running both client side , server side - way you'll able verify file hasn't been corrupted in transit.

once you've worked out , when file has changed, you'll need decide it. example, if excel is adding timestamp, may want mask out when computing hash.


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