28,655 questions
There is MapFileAndCheckSum
How to get file hash in Windows with C++
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sValentin
81
Reputation points
I want to add an additional protection to check if the files of the program have been modified, and for this I want to get the hash of the files and compare them with the values that I know they should have.
Can this be done in C++ without using 3rd party libraries? If yes, can someone help me with code or link to learn Microsoft? I need for Windows only.
I'm not checking all the files, only a few that can be easily modified and that have really small sizes (around 70 KB in total).
Windows for business Windows Client for IT Pros User experience Other
Developer technologies C++
3,972 questions
Accepted answer
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Castorix31 90,681 Reputation points2023-11-16T14:20:23.5266667+00:00 -
RLWA32 49,536 Reputation points2023-11-16T14:55:29.17+00:00 If the questioner is not seeking to get a hash for an executable this function's documentation contains the following caution "Passing a Filename parameter that does not point to a valid executable image will produce unpredictable results. Any user of this function is encouraged to make sure that a valid executable image is being passed."
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sValentin 81 Reputation points
2023-11-16T15:18:30.7+00:00 Do I get this right, in that MapFileAndCheckSum return the "raw" CheckSum of a file, and in the exemple I mentioned with certutil, that command takes this value and applies a hash SHA256 to it?
I tested MapFileAndCheckSum on two files with the same size but different content and it did return a different number, and then on two copies of a file and it did return the same number.
//Edit: Reading a bit more about this, I don't think that is the case.
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sValentin 81 Reputation points
2023-11-16T20:31:30.5366667+00:00 I'm going to use MapFileAndCheckSumW as it is easier for me to implement it and it is enough for my use case. Thank you!
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RLWA32 49,536 Reputation points
2023-11-16T09:24:38.01+00:00 -
sValentin 81 Reputation points
2023-11-16T12:17:37.8066667+00:00 I tried to follow that, but it was beyond me. Is there no simple function like for example BOOL CheckSum(FileAbsolutePath, HashAlgorithm (SHA256), HashValue);? How cmd certutil -hashfile file.extension SHA256 returns the hash value.
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sValentin 81 Reputation points
2023-11-16T20:29:58.74+00:00 While using a hashing checksum method would be more professional and recommended, it is beyond my C++ knowledge, I'm only using it to make DLL files for JNI, so I'm going to go with MapFileAndCheckSumW as my use case isn't for sensible information. Thanks for your time!
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