@OP: You should ignore the small fighting and arguing here around, and don't get upset by it, or fooled by it. People here they know what they are talking about. RDS is our expert in cryptography, and if he says it is not possible, than it is not. For the "machine" you talk about, even if you used the weakest key option for it, you still have to deal with about 1.2*10^24 combinations (about 80 bits, or 2^80, using some [URL="http://en.wikipedia.org/wiki/Meet-in-the-middle_attack"]MITM scheme[/URL]). Even with a lot of computing power, you will get older, your children will get older, and your grandchildren will get older, before finishing.

[QUOTE=jyb;373096]Of course it's rare. Nonetheless, that's how you expressed it. The answer to "How long does it take to do one encryption?" is quite unequivocally an amount of time. Why not just acknowledge the completely inconsequential (though amusing, given the context) mistake, rather than trying to pretend it was somehow correct?[/QUOTE]

I choose my words carefully. I said "One encryption", not "one block".
And I am very well aware of the difference for a BLOCK ALGORITHM SUCH AS 3DES.

The former depends on the
length of the plaintext. The time to do an encryption is therefore a variable
dependent on plaintext length.

OP,

Modern cryptography is not a simple thing to break like it is in movies. If one random guy on the internet could guess a 3DES key by trying all the possible keys, why would anyone use 3DES?

[QUOTE=LaurV;373106]@OP: You should ignore the small fighting and arguing here around, and don't get upset by it, or fooled by it. People here they know what they are talking about. RDS is our expert in cryptography, and if he says it is not possible, than it is not.
[/QUOTE]

Read what I said. Where did I say that it is not possible?
I was excoriating the OP for posting something totally off-topic
and for failing to do even the most basic reading about the subject
before spewing ignorance.

[QUOTE]
For the "machine" you talk about, even if you used the weakest key option for it, you still have to deal with about 1.2*10^24 combinations (about 80 bits, or 2^80, using some [URL="http://en.wikipedia.org/wiki/Meet-in-the-middle_attack"]MITM scheme[/URL]). Even with a lot of computing power, you will get older, your children will get older, and your grandchildren will get older, before finishing.[/QUOTE]

More ignorance. You did not even read the Wiki article that you quote.
A MITM attack on 3DES does NOT require 2^80 time complexity.
In fact, the article gives an explicit estimate for 3DES. Note also
that MITM attacks have MASSIVE space requirements.

Brute force attacks on block ciphers are CERTAINLY possible.
They are just not PRACTICAL.

[QUOTE=R.D. Silverman;373128]I choose my words carefully. I said "One encryption", not "one block".
And I am very well aware of the difference for a BLOCK ALGORITHM SUCH AS 3DES.

The former depends on the
length of the plaintext. The time to do an encryption is therefore a variable
dependent on plaintext length.[/QUOTE]


Hi

R.D Silverman

Sorry to insult your Einstein brain mate, unfortunatelly not all of us probably spent the time in maths that we were required, or perhaps i speak for my self i don´t have a freeking clue about 3DES,

and yes i did google searches it would take around 2billion years to brute force.

ok i know

my plaintext is 128bits long / 16 byte hexadecimal plainhex information

so i have

for 1 byte 256 combinations from 00 to FF, ok i know its triple des so its encrypted K1K2 dividing the 112bits key into 2 64 bits keys, as i know the hardware and software that was used and due to its CPU and software limits, and taking huge amounts of time encrypt and decrypt, the tool had to use the following encryption method using 2 keys of 64bits


i have the plainkey 16 bytes
i have the encrypted 16 byte key

all i am missing is the chipering key 3des used to encrypt data and decrypt.

so i thought how many milliseconds will a normal 3des ecb decrypt aplication take to decrypt a 128bits key using a correct 3des decrypt key+encrypted content also 128bits size.

ok also for a fact

i know the first byte of the key does not use hexadecimal FF so that should reduce sometime...

As it takes an average of 250 to 400ms to decrypt 1 message using 3DES algorithm so i can make maximum 2 to 4 attemps per second...i would need around 4billion pcs, around the scope to get som real testing done in a lifetime...

Anyways i understand the bruteforce is undoable due to the amount of time required..


PS- whats amazing here is a place full of Eisteins here, and my post was still checked by another Einstein before was submitted into the open wide forum, as it was stated that my post would be submitted for clearance after a checkup by one of the mods, aparently he also does not have a clue and he allowed my post to be posted..

[QUOTE=R.D. Silverman;373131]You did not even read the Wiki article that you quote.[/QUOTE]
Busted! That is true, I don't usually read the things I link to. The links are not for myself, but for the guys who want to read more. Once I linked to something, I know - at least vague - about the existence of that something. I just happened to know that the 3des can be attacked with MITM, and the complexity of it is close to 2^80. You can think about why is so...

And don't tell me you read all the articles you link to, before you release the posts :shock:

(at least, your boosting was good, because I went back to the article and read it, thanks!) :razz:

[QUOTE]…and my post was still checked by another Einstein before was submitted into the open wide forum, as it was stated that my post would be submitted for clearance after a checkup by one of the mods, aparently he also does not have a clue and he allowed my post to be posted.[/QUOTE]Please do not equate post approval with that moderator agreeing that your post has merit.

The moderation queue is there just to block spammers and bots.

We think most moderators take a laissez-faire approach to the content they allow into the forum. How else can you explain the mysterious wonders of the [URL="http://www.mersenneforum.org/forumdisplay.php?f=56"]Miscellaneous Math[/URL] sub-forum?

:ttu:

...and moving to Misc.Math
 

Vee ah not heeah to suppress free sprache, ja?
:offensive:

[QUOTE=t3st3r10;373319]Hi

R.D Silverman

Sorry to insult your Einstein brain mate, unfortunatelly not all of us probably spent the time in maths that we were required, or perhaps i speak for my self i don´t have a freeking clue about 3DES,
[/QUOTE]

Mature, intelligent people do not prattle about subjects that they
do not understand and have not studied.

If you know nothing about this subject, then it is reasonable to ask:

What compels you to post?

<plonk>

[QUOTE=LaurV;373322]Busted! That is true, I don't usually read the things I link to. The links are not for myself, but for the guys who want to read more. Once I linked to something, I know - at least vague - about the existence of that something. I just happened to know that the 3des can be attacked with MITM, and the complexity of it is close to 2^80. You can think about why is so...
[/QUOTE]

You STILL haven't read the article you quoted and you STILL are ignorant
about this subject. The complexity is not "close to 2^80" except in the
vague mathematical sense that any finite number can be approximated by any other finite number. The complexity is much higher than 2^80.

[QUOTE=Batalov;373327]Vee ah not heeah to suppress free sprache, ja?
:offensive:[/QUOTE]

Ja -, I mean nein, vee ahh nicht da to engage in die Sprachfreiheitsunterdrückung, or in any uzzer achtundzwanzig-Buchstaben-long bad sings. Every contributor ist völlig frei to be as big of a Trottel, Dummkopf oder Vorchußlorbeereneinsammler [dang, I love engaging in profligate German-compound-nounery] as he vishes.