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Clarification on encryption/decryption speed

Topics: Technical Issues, Users Discussion
May 10, 2016 at 11:52 AM
Edited May 10, 2016 at 11:54 AM
Hi, I plan to encrypt some old external USB 2.0 drives. Just to confirm, if their read-write speeds are less than the values in the performance benchmark, does that mean using even the slowest encryption method won't have any impact on the read-write performance? I just wanted to check in case it is referring to something else.
May 10, 2016 at 2:42 PM
Edited May 10, 2016 at 2:46 PM
The performance also depends on the speed and availability of your CPUs during disk intensive operations with other workload from running the OS and other applications on your PC.

The only way to know is to install VeraCrypt and run the VeraCrypt benchmarks which is not using your old external USB 2 drives. However, it will give you some idea based on your CPU and which encryption or cascade encryption you select. The benchmark is not going to be exact but a good estimation.

Tools > Benchmark
May 11, 2016 at 6:05 AM
Your speed will be 80% compared to unencrypted if you are very lucky, have aligned partitions formatted to MB boundary and NOT CHS.
That is because veracrypt is not optimized for SSD/Flash usage at all and because of this it does various quirks. That is speed is unpredictable.

You can use crystal disk mark to benchmark you unencrypted then encrypted to see for yourself.

You can use dfb64 to also see how flash behaves.

I think it is better to use diskcryptor because it is optimized for ssd/flash, speed drop is very small if at all.

Furthermore during my tests of VC the cluster size inside the containers needs not to match the cluster size of you flash disk ! How crazy is that???
That means your flash performs top speed say at 16kb cluster size, but your containers needs 8kb cluster size to be usable. This contradicts vmdk volume recomendations !

Something strange is going on inside VC regarding speed that's for sure. Imagine you have SSD disk you have 80% speeds, then you create container on that disk and again 80% speeds or lower (did not test this scenario)
May 24, 2016 at 1:36 PM
I dont think it is possible to feel any performance difference while working with encrypted and unencrypted data. No matter how hard i try, unless i use some serious stopwatch to measure things, its all the same to me.
May 25, 2016 at 8:16 AM
Edited May 27, 2016 at 12:49 PM
I don't feel any difference in here too, I have some external ultra high speed flash drives and they behave almost like they should, sticker says (up to) 200MB/s read, (up to) 100MB/s write and the actual speed is about 10% slower even without veracrypt. I have hw aes accelerated CPU, so there's no difference, but on old machines and netbooks without hw aes it might be hard to achieve speeds like 100MB/s in either direction when encryption is used.

EDIT: I consede, that SDXC might be right. Today I placed some large files into vc container on the fast usb3.0 flash drive and write speed dropped from 100MB/s to 10MB/s eventually. I don't know what's up with flash drive, but magnetic external usb3.0 hdd does not have any problem and works ~100MB/s, but having only 10% of the write speed the flash device is capable of is a disaster. Two days ago the same flash and same container was as fast as unencrypted, I put into this same container several tens of GB, today 10GB took like forever. Strange indeed.