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I'm trying to extract binary data from QR-code with zbar (the QR-code was originally encoded using the iOS SDK passing a NSData object). Unfortunately the ZBarSymbol class only provides the content in a NSString member. Trying to extract a NSData from it using NSISOLatin1StringEncoding seems to work but still fails in some occasions.

I see in the zbar implementation that it is possible to access an object of type zbar_symbol_t that contains a pointer to char. By looking into it, it seems to contain the original content but with additional data of some kind, this is an example:

Original data: 9e7328c16bca3aaff532440917e4df6e155b96bd
Data in zbar_symbol_t: c29e7328c3816bc38a3ac2afc3b532440917c3a4c39f6e155bc296c2bd

Anyone who knows what is exactly that data in zbar_symbol_t, why it is different from data I originally placed in the QR-code and how it is possible, if possible at all, to extract my original data from that?

Luca Carlon
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1 Answers1

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I am not sure what those bytes represent, probably zbar is trying to interprete the bytes as a UTF-8 string even though the QR is in byte mode.

Switching to zxing fixed everything, there is no interleaved unexpected byte and the raw data contains the entire QR code including the mode, terminator, padding etc... Also it seems to never fails, while zbar seemed to fail sometime.

Luca Carlon
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