Re: FileCopy overwrites the existing file

This is weird but I will somewhat defend Anton. I do suspect that you are
correct and he doesn't understand the difference between key lengths in
symmetric and asymmetric encryption keys.

Looks like a bit of "ad hominem" argument, don't you think???

To be honest, your latest post has not yet demonstrated your in-depth
understanding of the topic either......

This is the question not only of a key length but of the data set as
well....


If you are 100% sure that your algorithm is unbreakable by anything but
"brute-force" attack, you can feel pretty secure even with 128-bit key.
If data sample is relatively small, symmetric algorithms tend to be
less likely to submit to "intelligent" attacks (which is modulus
decomposition for asymmetric algorithms), so that they normally
require shorter keys. At the same time, when trying to break the
symmetric encryption, they normally try to detect some patterns, and
the larger the data sample is, the easier their task is. If some
"plain-text" is known in advance, their task gets simplified
dramatically


Here we speak about the data samples of the size of *hunderds of GB*
with some "plain-text" (i.e. OS-related stuff) known in advance, so
that symmetric algorithms that are perfectly safe for encrypting some
files or messages may be not-so-reliable here - probably, you would
have to go for asymmetric ones, and, hence, pay performance penalties

Anton Bassov


David J. Craig wrote:
This is weird but I will somewhat defend Anton. I do suspect that you are
correct and he doesn't understand the difference between key lengths in
symmetric and asymmetric encryption keys. With the explosion in the number
of processors available in a single system, it might be better to protect
your data with a symmetric encryption key of 512 bits if you need it to be
protected for more than a few months. Even RSA should have key lengths of
2048 or larger.

"Grzegorz Wróbel" </dev/null@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:elhmda$5dd$1@xxxxxxxxxxxxxxxxxxxxxxx
anton bassov wrote:
Pavel,

But what about the performance penalties that you are guaranteed to
encounter if you implement encryption at so low level????
My Thinkpad laptop has disk encryption,
probably it is done in the ide controller.
The disk performs not worse than in other models.

I think it mainly depends on the encryption scheme.....



Have you got any idea about the encryption scheme that your laptop
uses? I think that, because of government regulations, it must be
something not-so-strong, so that your disk can be decrypted by someone
with a special equipment pretty easily.....


However, imagine if you used 1024-bit or 2048-bit encryption - how fast
would it be????

For symmetric encryption 256bit is far beyond the reach of anyone to
decrypt, with good algorithm even 128bit is considered secure. And these
algorithms (symmetric) are fast as hell, here even large key wouldn't be a
problem. 1024 or 2048bit key encryption is needed for non-symmetric
encryption schemes like RSA. And this algorithm is slow, because it
requires specific numerical operations (ie raising to the power modulo)
using 1024-bit or 2048bit integer numbers.


--
Grzegorz Wróbel
http://www.4neurons.com/
677265676F727940346E6575726F6E732E636F6D

.

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