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  1. #25
    Join Date
    Dec 2013
    Thanked 45 Times in 37 Posts
    Could someone please me to do some testing with my version 47, which includes (perhaps) a pretty fast but reliable verifier?
    Essentially, the CRC32 codes of the individual files are stored during the compression phase, HW calculated (but not very smart).

    During the test they are checked (default setting) or even re-readed from the files on disk (switch -crc32).

    C:\zpaqfranz>zpaqfranz a r:\unnoo f:\* c:\dropbox\dropbox\* -test -crc32
    zpaqfranz v47-experimental journaling archiver, compiled Dec 25 2020
    Creating r:/unnoo.zpaq at offset 0 + 0
    Adding 35.277.684.778 in 193.591 files at 2020-12-25 10:11:03
    f:/System Volume Information/klmeta.dat: error sharing violation8 89.050.678/sec
    99.71% 0:00:00 35.171.430.059 -> 18.581.200.867 of 35.273.997.866 104.057.485/sec
    211.530 +added, 0 -removed.

    0.000000 + (35273.997866 -> 27200.708309 -> 18680.869392) = 18.680.869.392
    Forced XLS has included 87.887.223 bytes in 582 files

    zpaqfranz: do a full (not paranoid) test
    1 versions, 211530 files, 520146 fragments, 18.680.869.392
    Checking 35.273.997.866 in 193.590 files -threads 12
    99.82% 0:00:00 35.208.949.750 -> 18.660.742.481 of 35.273.997.866 81.502.198/sec

    Checking 299.475 blocks with CRC32 (34.485.752.228)
    Re-testing CRC-32 from filesystem
    ERROR: STORED B3FBAB1C != DECOMPRESSED 348150FB (ck 00000001) c:/dropbox/dropbox/libri/collisione_sha1/shattered-1.pdf
    ERROR: STORED B3FBAB1C != DECOMPRESSED 348150FB (ck 00000001) c:/dropbox/dropbox/libri/collisione_sha1/shattered-2.pdf
    Verify time 111.625000 zeroed bytes 788.245.638
    ERRORS : 00000002 (ERROR: something WRONG)
    SURE : 00193588 of 00193590 (stored=decompressed=file on disk)

    544.328 seconds (with errors)

    I would therefore need some add () with the -test option of very weird file (all zeros, part zeros part not, small, large, duplicated and un-duplicated etc)

    zpaqfranz a z:\pippo.zpaq c:\mydata d:\mydata2 -test

    A fast (not filesystem-reload) can be done via t(est)
    While not optimized it should be pretty fast
    zpaqfranz t z:\pippo.zpaq

    Slow (file system reload)
    In this case each file is reread by the filesystem, and CRC32 codes recalculated. Normally by CPU hardware instructions, so the bottleneck is normally the media transfer rate
    zpaqfranz t z:\pippo.zpaq -crc32

    The 64-bit Windows binary is here

    Using a double check, SHA1 on individual fragments, and CRC32 on the entire file, I hope to catch even SHA1 collisions.
    A pretty brutal method, but it should work

    Thank you and and merry christmas
    Cпасибо и счастливого рождества
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