Huh?Quote:
Originally posted here by i2c
side channel attacks - if the encryption is done in a dedicated microprocessor, then unlike the ideal mathmatical equations, you can measure the power comsumed by the chip and use statistics to figure out a key.
i2c, Do you have any links on this? Key words to search on?
/me runs to google to search side channel attacks.
When someone talks about "cracking" or "breaking" an encryption algorithm, they always seem to mean this: the "attacker" decrypted a message by guessing the secret key that was used for the encryption. This is not breaking or cracking a particular algorithm. But it does demonstrate the importance of key size. The key size -- the number of bits used to store the key, which is an integer number -- determines the size of the key space, the number of possible keys that can be used. If you knew that to decrypt a message you needed to guess a number between 1 and 10, would you feel challenged? How about between 1 and 1000? How about 1 and 1^38 (1 followed by 38 zeros). That is (roughly) the key space using a 128-bit key. For comparison purposes, let’s use a (so far) non-existent computer that can guess 1 trillion (1 followed by 12 zeroes) keys a second. On average, it would take around 2 million million million (2 followed by 18 zeroes) years to guess the key.
There are quite a few side-channel attacks. A few years ago someone went and sort of scientifically discovered that their motherboard's tone changes depending on the operations the microprocessor is carrying out. Basically they ran loops of specific functions that the microprocessor would carry out, and they recorded what was audible, and matched it with the operation being carried out, etc. There are others people are more familiar with, such as TEMPEST, but for the most part all of it gets you interesting information about the current state of the machine which may help you guess the "random" numbers being generated or processed.
Computationally 2^128 is pretty large as arindamraha mentioned -- approx 340,000,000,000,000,000,000,000,000,000,000,000,000. Also 2^256 is essentially a number with 77 digits. Things of such size would be very ineffecient to brute force every single combination. With a perfect cipher, you should have to make that many guesses before "cracking" it...
But hidden (or in many cases, clearly visible) problems in an algorithm can greatly reduce the effective keyspace from 2^128 to 2^14 or so.
The most common example here is a repeating XOR encryption technique that many "newbies" rely on. Don't get me wrong, XOR is awesome and perfect for a one-time-pad but, unless you really know what you're doing to avoid the issue, having a 128bit XOR key that cycles to encrypt a large file presents the known-plaintext attack (or some other variation) since its use is so highly predictable and well understood.
In the end, it boils down to what 128-bit encryption you're cracking. It can be as simple as 4096 guesses before a key is found, or it could be a full-blown 3.4*10^38 guesses.
www.ee.usyd.edu.au/~rjunee/sc_side_channel.pdf
(note the extenstion, be careful on 56k)
Side channel means are vast, for instance you could meassure the current, use the method Tim said, measure the EMC, maybe even the heat but this would be cumulative.
For most means you need advanced electronics equipment that can output to a computer for analysis, although I think (can't find much on it) that implementation of this stuff in DSP or PFGA with DSP IP could work, would be interesting to find out.
i2c
Not easy at all. Very time cosuming if your running Internet Explorer 6 it uses 128 bit encryption. To find out your cipher strength Open IE click on Help, go down to about IE look at cipher strength. Also, if your running IE it likes to use;Quote:
How easy would it be to crack a 128 bit encryption?
SSL 3.0 RC4 with 128bit encryption (High); RSA with 1024 bit exchange
Which is pretty secure for data transmissions in my opionion. But to answer your question This would take countless days and nights and a lot of processor time. Its definitely possible just very time consuming.
yeah 128 bit encryption is very much crackable... not kind of swordfish which is more of eye candy in graphical way..
but the pioneer of all the encryptions AES can be cracked by using good cpmputer power..
as aes's biggest problem lies in its easy mathematical implementation..
n even some of the sucessful chosen plaintext attacks has been done so far on advanced encryption standard.
Hi
It has been said: There are several forms of algorithms,
which also influences whether an encryption scheme can be
"cracked" using some attacking method. The most important
difference is between symmetric (like DES, 3DES, ...) and
asymmetric ciphers (RSA, ...): While the 128bit key in AES
is secure, it would not be for the RSA (typically 1024,
2048 and larger keys).
Neo143, what are you talking about? DES, which has a 56bit key
and one could name the pioneer of all encryptions (bah),
has been cracked. But AES[1a,1b] with 128bit or more?
As for 2005, only a few possible attacks for AES are known, e.g.
a theoretical XSL attack[2], which is very resource consuming.
If I am incorrect, I have missed recent development and I
apologise.
Cheers.
[1a] http://www.cryptosystem.net/aes/
[1b] http://www.iaik.tu-graz.ac.at/research/krypto/AES/
[2] http://en.wikipedia.org/wiki/XSL_attack
What the hell are you talking about? What 'chosen plaintext attacks' have been sucessful against AES? Yes, there was a potential vulnerability announced a few years ago...but only under near-absurd conditions, if memory serves. No one stopped using it.Quote:
Originally posted here by neo143
yeah 128 bit encryption is very much crackable... not kind of swordfish which is more of eye candy in graphical way..
but the pioneer of all the encryptions AES can be cracked by using good cpmputer power..
as aes's biggest problem lies in its easy mathematical implementation..
n even some of the sucessful chosen plaintext attacks has been done so far on advanced encryption standard.
That's like claiming a token is insecure for two factor auth. because if you steal the seed, know the algorithm, and guess the users PIN/password, you can duplicate the passcode. Well yeah, duh. And if you can accurately guess the numbers for the next lotto drawing, you'll be really rich.
Let's talk about reality.
This is a little dated but I think it still makes a good read on the issue and clarifies some issues regarding this topic...
http://www.avolio.com/columns/pkiq+a.html
tahrizi -> Fred Avolio] how long 128 bit encryption could be crack
Eg ;)
Uhm, is there a good reason you are directly quoting information from a website that seems to be directly attributed to a person (Fred Avolio to be specific) and presenting it as your own? This attribution is implied, since you don't quote out the entry or link to the site. Interesting.Quote:
Originally posted here by arindamraha
When someone talks about "cracking" or "breaking" an encryption algorithm, they always seem to mean this: the "attacker" decrypted a message by guessing the secret key that was used for the encryption. This is not breaking or cracking a particular algorithm. But it does demonstrate the importance of key size. The key size -- the number of bits used to store the key, which is an integer number -- determines the size of the key space, the number of possible keys that can be used. If you knew that to decrypt a message you needed to guess a number between 1 and 10, would you feel challenged? How about between 1 and 1000? How about 1 and 1^38 (1 followed by 38 zeros). That is (roughly) the key space using a 128-bit key. For comparison purposes, let’s use a (so far) non-existent computer that can guess 1 trillion (1 followed by 12 zeroes) keys a second. On average, it would take around 2 million million million (2 followed by 18 zeroes) years to guess the key.
Don't believe me? Follow the link in Egaladeist's previous post.
BUSTED
Also...two posts, and a greenie already? WTF over? It has been brought to my attention that I had a dumb-ass moment here...ALL new users have 1 greenie. I confused that with a new user giving you APs...they show up as a grey dot instead of green/red. I assumed the same for users <50 APs. I was a dumbass. Sorry. Not the first time it's happened...certainly not the last. You may now carry on with your lives.