![]() ![]() If you do so, than computing the checksum will be useless, you can simply compare the written data to original data as you are currently doing. There is no point in computing the checksum from your own computer, attempting to write data, because in this case, the whole data will be read back over the network again. The data written to the database will be available to the hash function on the remote computer locally (on the same machine) and checksum will be computed faster. You can accomplish this by wrapping your hash function in an ActiveX component and intantiating it remotely on the target computer. Whichever method you use, you should write your code in such a way that checksum of data written to database is computed by the computer hosting the database. Auto compare against the clipboard, the local hash, and the BSD format. I don't know which library is required for creating CAPICOM.HashedData object. File integrity checksum calculation for large and almost unlimited file sizes. Unfortunately, on my computer, running Win7 Pro 64-bit SP1, it throws error 429, "ActiveX component can't create object". If we number the slots from the right, starting with 1, the even-numbered input slots have a strange digit. It looks like an ordinary chain adder, but it does not have a tens carry and all chains add to the same number in the small window at the far right. We are not using it for encryption, when the knowledge of actual algorithm and proof of its reliability is of acute importance.Īt least, it is better and faster than adding or XORing byte values together in a loop.Īs far as simplicity is concerned, strongm's MD5HashDigest function also looks a treat. Luhn invented a mechanical calculator for this checksum (Luhn1960, Figure 4). I proposed the HashData solution because of the "very, very, very simplest algorithm" requirement.Īlthough the algorithm is not documented (at least I am not aware of it), I don't mind using it for computing a simple one-way checksum for data integrity check. It computes a 16-bit checksum by adding up all bytes (8-bit words) of the input data stream. 'CRC_Calc = Chr(CRC_value Mod 256)
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