A checksum is a value created from a binary file that can be used to validate its authenticity and integrity. An example of a checksum is MD4, MD5 and SHA-1.

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Is verifying a MD5 sum after copying 100GB of data safe?

I'm copying 100GB from a Windows 7 workstation to 2 external drives (if you have only one backup, then you have none). All files have a MD5 checksum. I've verified all MD5 checksums on the external ...
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3answers
4k views

What are these Google SHA1 images? [closed]

If you look at this page you'll see an monochrome image. Above it says Tip: Use the SHA1 checksum shown to verify file integrity. However, I don't know if that's related. What are these ...
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5answers
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Does recompiling a program produce a bit-for-bit identical binary?

If I were to compile a program into a single binary, make a checksum, and then recompile it on the same machine with the same compiler and compiler settings and checksum the recompiled program, would ...
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6answers
224 views

Checksum for Protecting Read-Only Documents

My father owns a small business and has to hand over several year's worth of financial documents to his insurance's auditor. He's asked me to go through and make sure everything is "read-only" so the ...
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1answer
756 views

Does Windows calculate CRCs to check every file operation?

When Windows encounters a file corruption on a file system, it may return the following error message: Data error (cyclic redundancy check). This suggests Windows checks every file operation ...
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File copy program that generates checksums of the data while copying too

My question in short: is there a tool that copies a file from directory A to B while, simultaneously, generating the checksum of the file it has copied/read, without doing an extra read/pass just to ...
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3answers
2k views

Is there anything like HashTab for Linux?

I've recently installed Linux, and I know that you can use "md5sum filename" in terminal, but on Windows there is an AMAZING software called HashTab that incorporates it into the shell. Its awesome, ...
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2answers
365 views

Mass Checksumming tool for Windows?

I'm looking for a command line tool for windows that will go over a directory tree (recursively) and output a list of all the files in there, and a checksum for each file (can be CRC, MD5, whatever). ...
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1answer
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recursive file/directory verification on linux

What would be a command structure or simple bash script to run to compare all files in one directory with all files in another directory, verifying their data are identical, or not, down to the bit? ...
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4answers
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Single unix command to correctly transfer a large file?

I am trying to transfer a large (~3GB) file between two unix machines. I can use scp or rsync, but sometimes the transfer is corrupted. (I have to check manually.) I can split the file into pieces ...
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2answers
600 views

TCP Checksum, why?

Why does TCP need a checksum, when lower layers do integrity checks anyways (like Ethernet CRC)?
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3answers
2k views

How does a downloaded ISO get corrupted? [duplicate]

Possible Duplicate: Is it possible to get corrupted download with http? I downloaded an ISO for fedora. Went to install it as a VM. It failed 5 times the installer. The warning for the ...
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1answer
457 views

Is there a utility to verify the checksums of every Windows file?

I would like to know if there is a utility to verify the checksums of every Windows file on my Windows 7 Ultimate system. It seems on the surface such an obvious utility but I don't ever remember ...
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1answer
2k views

What is the best way to make Calculate SHA1 as a context menu option in Mac OS X?

In order to calculate the SHA1 checksum of a downloaded file, I could type /usr/bin/openssl sha1 in Terminal and then drag there the file which I want check. To make it simpler, one could enable a ...
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3answers
3k views

A gigabit network interface is CPU-limited to 25MB/s. How can I maximize the throughput?

I have a Acer Aspire R1600-U910H with a nForce gigabit network adapter. The maximum TCP throughput of it is about 25MB/s, and apparently it is limited by the single core Intel Atom 230; when the ...
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1answer
117 views

Why do repeated downloads for Google Chrome setup have each time different hashes?

I've tried downloading the setup files for a standalone offline installation version several times in rapid succession. Each next file has an identical size but a different hash. Why is that? Do they ...
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4answers
206 views

Why would I check my download against a checksum provided by a mirror site?

I thought the point of distributing md5 checksums was so the end user could verify the integrity of the download. If a high traffic site points me to a mirror site for download, why would I want to ...
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3answers
255 views

How do I check the checksum of a download and why should I?

My memory isn't great but I think five or six years ago, when I downloaded some package, there was never a checksum line under the download icon on the webpage. And no instructions to "check the ...
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3answers
3k views

Is it possible to download corrupted torrent files, even with a download client builtin checksum verification?

I downloaded some mkv/mp4 files with my new router (I can download directly from it, using transmission), and all of them seem to be corrupted: lags, strange artifacts when using vlc, crashes with ...
2
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2answers
227 views

HTTP downloader with good integrity(hash..probably md5) checker built in [closed]

I'm trying to download xcode v3.2 from the Apple Developer Connection website, but everytime I download the huge file, it fails to mount due to a checksum error. It's really frustrating! BitTorrent ...
2
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1answer
498 views

How does one verify the PGP RSA and/or DSA checksum signatures for putty?

To verify the download integrity of putty, how is the best way to first verify the "SHA-512: (RSA sig) | (DSA sig)" PGP signature of these check-sum files for putty? (I am guessing "sig" means ...
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1answer
3k views

How is TCP/UDP checksum working?

I used raw socket to create some UDP packets and then send them to a UDP server I notice that when I put a wrong UDP checksum number the UDP server doesn't accept it, but if I put all 0 on the ...
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3answers
2k views

Looking for OS X utility to verify/validate copied files/directories - checksum / SFV / MD5

Looking for the best way to easily validate the integrity of files/folder in OS X when copied from one location to another. I've downloaded SuperSFV but it appears to be very slow. Also new to the ...
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2answers
1k views

How do downloads become corrupt? (SHA1 value varies)

I downloaded VS 2012 using IDM. While I did pause and resume several times, it downloaded successfully. BUT, the SHA1 and CRC values do not match with the given values in the website. This means that ...
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2answers
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Checksumming an entire CD/DVD

I'm publishing a set of documentation to be delivered on CD. My Company's European production manager is concerned that he has no way to verify that the data on the discs he produces is correct. He ...
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2answers
740 views

Verification of files on backup media - after the backup

I have a system in place where I back up my work files daily to a portable hard drive. I actually have two portable hard drives - one is stored off-site and I swap them regularly. I also keep my ...
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1answer
210 views

Hardware digital signature

Is it possible to show how generate a digital signature, a checksum, or something along those lines based on your computer hardware using an Ubuntu Live CD? So, once the first digital signature is ...
2
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1answer
191 views

md5sum only new files?

I have a directory containing files and an md5sum.txt file. I add a file new files to the directory. I would like add md5sum sums for all files that are not in md5sum.txt. Is there a simple way to do ...
2
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1answer
2k views

Is it possible to check a PDF for data corruption?

I have some PDF documents and I'd like to check them for possibile data corruption, even if I'm able to display them without problems. I don't really know if PDF documents store an embedded checksum ...
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2answers
5k views

Keyboard error or no keyboard present

I've been fighting with this for a couple of weeks when booting my PC: Error keyboard or no keyboard present CMOS checksum error -Default loaded And of course there is no way to go any further ...
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1answer
99 views

File corruption detection strategy

due to current high price of hdds, I would like to switch from running RAID1 to JBOD + offsite backup (Backblaze). In theory it's a much better approach (if PC gets fried by lighting strike, I still ...
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0answers
87 views

MD5 for Git's git-credential-osxkeychain executable? [closed]

I'm setting up a GitHub account and have downloaded Git's credential-osxkeychain executable via the Password Caching section of GitHub's instructions. But... I am paranoid enough to look for some ...
2
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1answer
75 views

Backup solution: hash/checksumming and/or error correction

I'm trying to keep my data well protected with backups, using multiple hard drives (basically swapping the backup disk out every week). For checking validity, I was originally planning on md5summing ...
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1answer
705 views

Is it possible to check a FLV for data corruption?

I have some FLV videos and I'd like to check them for possibile data corruption, even if I'm able to play them without problems. I don't really know if FLV videos store an embedded checksum string for ...
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2answers
4k views

“CMOS check sum error” while booting

I am using an HCL desktop system (Core 2 Duo, 1 GB RAM, Windows XP SP2). While booting I got the following message. CMOS check sum error. Press f1 to continue When pressing F1 it is working ...
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3answers
289 views

tool for maintain incrementally the checksum of a large set of files

I need a tool to generate and maintain the checksum (MD5, SHA1, it does not matter) of all files in a folder or a set of folders, recursively. Sometimes I will add/update/remove some files and I ...
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1answer
756 views

How to get rid of UDP checksum error messages in virtual console?

Whenever I am streaming a video in the web browser, while connected to my school LAN via ethernet, and switch to the virtual console (ctrl-alt-f1) on Ubuntu, I get an error that looks like the ...
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2answers
165 views

how to backup only files paths, names, sizes and checksums?

I'm looking for an application which will allow me to select some folders, and then regularly backup only complete paths, names, sizes and checksums of the files within those folders and their ...
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1answer
114 views

Can I rely on CDs and DVDs for storage when I copy them without errors?

I have old CD and DVDs. I am copying the files I have on these discs to my hard drive, but can I be sure that these files are not broken? I copy these files with no errors and don't want to keep the ...
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1answer
189 views

sourceforge checksums: Where are they? [closed]

I've been particular about checksumming all downloaded software. Today, trying to download from Sourceforge, I could not find any checksums for the projects. Am I just missing them or are they not ...
1
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1answer
234 views

Tool to maintain/keep track of filesystem content integrity?

I'm looking for a tool to maintain the integrity of a filesystem and it's contents using checksums. Effectively storing a list of checksums/filename pairs somewhere on the filesystem in a way that can ...
1
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1answer
87 views

What does my computer do if it receives a data-packet with a wrong checksum?

Since modern routers don't check the header-checksum any more to increase performance I'm wondering what my computer is doing with defective data-packets? Further reading links appreciated.
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3answers
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How can I copy files to an external drive and verify their integrity in OS X?

I'm moving large amounts of data from one external drive to another larger one. The files are important and the smaller drives need to be cleared and reused (HD camera). Is there some utility for ...
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1answer
135 views

On Mac, after downloading a file, how to you do a checksum?

I want to do a checksum on a file I downloaded on my Mac. How can I do this?
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2answers
529 views

Calculate checksum of file from right-click menu? [duplicate]

Possible Duplicate: Looking for MD5 utility that integrates to Windows What would be the easiest way to have the checksum of a file shown in a message box using the right click menu on the ...
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3answers
981 views

Solution for noisy network that corrupts downloaded files

The network on the company where my wife works sucks BIG TIME. Almost every single file bigger then a few hundred kB is corrupted during download and even web pages are sometimes garbled. We checked ...
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0answers
129 views

Window Vista cannot create new folder, note, etc when right click and recent items forever empty after crashes

Basically my computer crashes and after I reboot I got a checksum error, so I reboot again and these problems appears: 1):Unable to create new folder, notes, zip file,etc. (when I right click in ...
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82 views

Cannot open an encrypted file on OS X

I cannot decrypt files on OS X (10.6.8 and 10.8.2) which I have encrypted on Ubuntu (10.04) using ccrypt. As a similar problem, I have a password file created with KeePassX. I just cannot open it on ...
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3answers
301 views

How do I verify the authenticity of a linux system executable?

I'm aware of md5sum and gpg but I have no idea if there are recorded checksums for whatever current version of ubuntu is installed. Do these get recorded somewhere? Specifically I'm suspicious that ...
0
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1answer
3k views

Microsoft Windows ISO checksums

Is there an official source for Windows ISO (XP+) checksums, online? Wanting to download some older Windows versions, for support purposes, but they don't appear to be available on Microsoft's ...