Total Commander

The directory comparison is much better by HASH, because it is much faster especially if there are large files, and especially because it works a lot with clouds mounted as a disk drive.
THE COMPARISON WITH HASH IS FAST, SPEED AND ALSO TODAY IS ESSENTIAL FOR THE HUGE FILES, AND FOR THE CLOUD AND FTP & SFTP MOUNTED AS DISK DRIVES.
Please doing it as soon as possible, before another utility does it before you.
Many thanks.
Vote for this essential addition.

streik,
You'd have to have the hash first.

Roman

Air Explorer compares with HASH, and it goes very fast.
The Hash can be obtained.
All comparisons, today are made with Hash, because they are very fast, and much faster.
That does not mean that it could also be left on, the byte-by-byte comparison.
But it is better and faster, the comparison with Hash.
Now imagine that to compare a file that I have mounted as a disk drive W: with a local drive, or with another cloud mounted drive in Z :, I had to download each and every one of the files on both sides, to be able to do a Comparison byte by byte. That would be darker, being able to make the comparison for Hash.
Today the comparison has to be done by forced Hash.
And so there have to be at least two options added.
One that would be Files - Compare By Hash ...
And another option added in Commands - Synchronize Dirs ...
add a box at the top left that says "by Hash".

To determine a file's hash, you have to read the full file. But that's exactly what the comparison by contents does. So, I don't see the advantage in doing comparisons by hash, except when the compared directories/files are on the same disk (leads to disk thrashing especially on HDDs).

Regards
Dalai

It seems to me that you can ask the server to send you the hash, with a command or instruction to both the cloud servers and the FTP servers.
This has to be provided by cloud and ftp servers, because otherwise the servers' programmers would be dumb.
The servers have to be able to calculate the hash with greater immediacy, than having to send the entire file, simply to be able to compare.

Example: Web page, where there is an explanation of how to request gas from an ftp server, after uploading or downloading a file, making a hash comparison, so that the server gives you the calculation, and thus be able to know if it is exact. the one you have in a local file, or on another server or cloud:
https://www.componentpro.com/blog/details/verify-file-hash-ftp-upload

streik,
But what you suggest is already done, read TC's Help file:

Compare by content via FTP is supported only when the server supports one of the following commands (and announces this via FEAT command): XCRC, XMD5, MD5, XSHA1. Total Commander then calculates the same checksum type locally as the server returns, and then compares the two.

Total Commander compares hash when the FTP server supports it.

Roman

You also have to allow it with clouds, when they are mounted as disk drives, and that's why you have to add those two options added.
One that would be Files - Compare By Hash ...
And another option added in Commands - Synchronize Dirs ...
add a box at the top left that says "by Hash".
At the same time, the hash comparison is much faster, if I am comparing a cloud with a real local unit.
Well, to a cloud, you can request the hash, and it sends it to you very quickly.
Much faster than having to receive the entire file first, which is what there is now. Well the comparison is by content. And it has to be allowed, and it is MANDATORY, the comparison by HASH.

streik wrote: 2020-03-16, 16:41 UTC You also have to allow it with clouds, when they are mounted as disk drives, and that's why you have to add those two options added.
One that would be Files - Compare By Hash ...
And another option added in Commands - Synchronize Dirs ...
add a box at the top left that says "by Hash".
At the same time, the hash comparison is much faster, if I am comparing a cloud with a real local unit.

But there is no protocol to deliver the Hashes for cloud files mounted as a drive ?

If Air Explorer and others can do a hash comparison, the server sends that information when the hash is requested. The hash request exists. And the hash submission also exists. and the hash reception also exists. You have to investigate exactly how they do it. But to exist, it exists with total security. Well programs like Air Epxlorer make a perfect hash comparison very fast. And if Others can do them, total commander who has much more experience, must also be able to do it.

For example, a little information sought in less than 2 minutes about the real existence and the request of the hash to OneDrive.

https://github.com/OneDrive/onedrive-api-docs/issues/1174

https://github.com/OneDrive/onedrive-api-docs/issues/46

https://stackoverflow.com/questions/31035544/how-to-search-by-file-hash-using-onedrive-sdk

https://rclone.org/onedrive/

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And here I have found information in 2 minutes of the real existence, and the perfectly possible request of the hash to Google Drive.

https://cloud.google.com/storage/docs/hashes-etags

https://cloud.google.com/storage/docs/xml-api/reference-headers#xgooghash

https://stackoverflow.com/questions/57752713/how-to-generate-hash-value-from-list-of-files-in-google-drive

https://developers.google.com/safe-browsing/v4/update-api

https://developers.google.com/safe-browsing/v4/reference/rest/v4/threatListUpdates/fetch#request-body

https://webapps.stackexchange.com/questions/39502/size-and-md5-hash-of-files-on-google-drive

A little information found in 2 minutes, about the Mega.nz hash.

https://mega.nz/SecurityWhitepaper.pdf

https://mega.nz/secureboot.js

Information found in less than 2 minutes about the real existence, and possible request of the Hash (for comparison of files uploaded or downloaded) in Dropbox:

https://www.dropbox.com/developers/reference/content-hash

https://dropbox.tech/security/how-dropbox-securely-stores-your-passwords

https://www.incibe-cert.es/sites/default/files/contenidos/estudios/doc/incibe_security_storage_dropbox_mega.pdf

https://www.quora.com/How-does-Dropbox-compare-files-to-update-them-efficiently

More information about requesting and comparing files in the cloud by hash, so you don't have to download the entire file.

https://www.airexplorer.net/en/download
(Search the page for the word "hash" without quotes.

https://www.airexplorer.net/en/help/
(Search the page for the word "hash" without quotes.

Using hash comparision to check if two files are the same
Hash value is a digital signature for each file. By comparing this signatures Air Explorer can know if the files are the same so Air Explorer in that case does not updated this file while synchronizes.

There are different hash functions and each cloud uses one of them. The hash comparison only can do with clouds that use the same hash.

Hash comparison:
-md5: local, 4shared, Google Drive, Baidu, pCloud.
-sha1: local, Box.com, OneDrive, pCloud.
-sha2: Dropbox.
-sha256: local, Mediafire.
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Additional Information. Here is a free file comparison program for various types of hashes. It works with local type files.

https://securityxploded.com/hashcompare.php

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