What is the fastest algorithm for verifying file integrity?
What is the fastest algorithm for verifying file integrity?
Checking the filesize.
The one rsync uses
crc32
return 1
>crc32
>integrity
It can be broken by brute-forcing just 4 bytes, user.
he said fastest. crc32 is a good integrity check against accidental corruption, but not a malicious hacker
this
escpecially if you want to run the program to verify file size without having to load all the file date (like with md5/sha)
also goot to use with an ssh explorer when you'd have to download the whole file to verify it's the same as the one you have on your desktop
data* not date
>crc32 is a good integrity check against accidental corruption
...in data transmission, eg. a packet protocol. For files it's far too prone to collisions, and of course insecure.
crc32 then md5/sha if it matches
On a corrupted disk there are like only a dozen of corrupted blocks
what you're saying would end up in doing an unecessary crc32 check for 99.99% of blocks
Just run a md5 check CRC32 is not that reliable and md5 is fast
I've always seen MD5 used for this.
If you're going to read every byte you might as well just feed it through $hash() anyway, passing it through crc32() is just wasting time.
Also MD5 is known insecure, use at the very least SHA-1.
Are you retarded?
OP is asking for file integrity check, MD5 is insecure for password hashing because it can be easily brute forced
Forgot to mention; if you're actually serious about file hashing then you're using a tree hash or hashing chunks. Not hashing the entire stream at once, because then you have no idea what part of the data is actually corrupted, just that it is or isn't.
Are you? You can fake MD5 checksums.
en.wikipedia.org
Secure file integrity will always require that you read the entire file. The fastest technique is to take a hash of the file, and compare the result to a known, trusted value.
SHA2 is probably the fastest, still secure algorithm on most platforms. SHA-1 is faster if you're willing to sacrifice some security. MD5 is insecure for this purpose.
Filesize doesn't confirm integrity
>You can fake MD5 checksums
You can fake ALL checksums.
The only variable is time.
See also:
blogs.technet.microsoft.com
DO NOT USE MD5 FOR FUCKING ANYTHING.
xxhash. crc and md5 are neither fast nor reliable.
It checks for SOME kinds errors, op never specified what kinds of errors he needs to check for.
>It checks for SOME kinds errors, op never specified what kinds of errors he needs to check for.
But so does reading the first bit...
You don't have to read the file at all to check its size.
Filesize followed by checksum appropriate for the level of confidence you want, usually.
Gentoo uses BLAKE2B, might be a good compromise for you too.
check byte by byte
>not bit by bit
HE SAID THE FASTEST YOU IGNORANT FUCK
>not half bit by half bit
I think verifying integrity with or without malicious actors involved are very different issues
If someone wants the wrong tool for the job you don't just give it to them so they shoot themselves in the foot, you salty fuck.
>not converting to analog
This.
If you're just verifying integrity between devices you own, or backup files, then things like CRC32 and md5 work just fine.
If you're verifying integrity of things you download of the Internet then use something more complex.
Why not?
OP here, I understand the faster typically the less secure, but I'm not looking for security. I'm just copying a 400GB archive from one drive to another and need something quick to make sure it didn't get corrupted in the process. I don't have a hacker trying to inject a RAT into one of the executables in it.
>Only 400GB
This will be super quick no matter what you use
$ cksum archive.zip
Run that once on host and once on target
Because most people aren't sociopaths.
without specialized hardware? maybe xxhash
Here's the thing. It doesn't fucking matter in terms of performance. Any half decent CPU can shit out CRC32 or SHA-512 of whatever you're copying around in an amount of time the difference of which you can't even perceive. The bottleneck is your storage devices, I guarantee you.
So just use the stronger one everywhere.