Calculating the CRC32 of the contents of a ZIP file

What’s the fastest way to check the CRCs of the files contained within a ZIP file?

I am currently unzipping the ZIP file (via the Shell with the unzip tool) to the temporary folder and then looping through each file and using the crc32 tool via the Shell to determine the CRC value (this is on Mac, I’ve been using the open source 7za to unzip and crc32.exe to determine the CRC on Windows).

This seems like a lot of legwork and isn’t as fast as I’d hoped. Are there any tools (either plugins or open source binaries I can bundle with my app) to get the CRC value of the contents of a ZIP file? Preferably without having to unzip the file as this takes time.

you can read file via BinaryStream.
Than run through CRC.

MBS Plugin has Adler32StringMBS and CRC32StringMBS functions.