待辦事項 #37418

啟用日期: 2017-08-03 00:52

最後更新: 2017-08-03 02:31

CRC64

回報者:c384mb負責人:(無)
優先權:9 - 最高里程碑:(無)
類型:特色請求嚴重程度:5 - 中
元件:(無)狀態:開啟
處理結果

細節

? Gtk2 and 7z Windows, check sums not the same on the same files. But 7z the same file say the identical sum in Windows (~2 month ago I check CRC64 with other file and check now CRС64). File on Ext2, VBox lan disk (lan folder). files are not moved from disk partition for checking.

https://s3.postimg.org/g5mmpbmo3/q5ete654grhd7eyefh.png

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Ticket History - 3/3 Histories

2017-08-03 00:52 Updated by: c384mb

  • New Ticket "CRC64" created

2017-08-03 01:46 Updated by: giorgio_tani

評語

Thank you for reporting. I've reproduced the problem and I'm looking in the issue.

2017-08-03 02:31 Updated by: giorgio_tani

評語

The implementation of the algorithm seems correct in PeaZip, and as for I was able to see the underlying library provides consistent output for all utilities it is implemented in.

The problem is that multiple CRC64 standards exists, see in example http://reveng.sourceforge.net/crc-catalogue/17plus.htm#crc.cat.crc-64 and https://en.wikipedia.org/wiki/Cyclic_redundancy_check#Standards_and_common_use

My software uses Wolfgang Ehrhardt's implementation (which is also used in a plugin for FAR Manager maintained by Wolfgang Ehrhardt himself), identified as CRC-64/WE in first link, while 7-Zip / p7zip uses Igor Pavlov's implementation (he is the author of 7-Zip, and of 7Z and XZ formats), identified as CRC-64/XZ in the first link.

While the algorithms are commonly referred with same name, they are inherently different and produces different results. I'll test better the issue, and I'll try to clarify the topic in documentation in future.


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