Examples of using Stream cipher in English and their translations into Serbian
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Colloquial
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Ecclesiastic
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Computer
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Cyrillic
Here, it gets encrypted using a stream cipher.
So these stream ciphers as normal they have a seed.
So I should say that the eStream project actually has five stream ciphers like this.
It's a very fast stream cipher, both in hardware and in software.
And, as far as we can tell,it seems to be unpredictable as required for a stream cipher.
The stream cipher, the original stream cipher must be secure.
And all that stream is encrypted using the stream cipher with key K. So that's perfectly fine.
So the CSS stream cipher is based on something that hardware designers like.
And these are the corresponding numbers for the stream ciphers that we looked at in the previous module.
It's a stream cipher that's designed for both software implementations and hardware implementations.
It's a very common mistake to use the stream cipher key, or a one time pad key more than once.
So, the stream cipher key or the one time pad key should never ever, ever, ever be used more than once. So.
So first of all the parameters for these stream ciphers are a little different than what we're used to.
So RC4 takes a variable size seed, here I just gave as an example where it would take 128 bits as the seed size,which would then be used as the key for the stream cipher.
You realize that some stream ciphers are designed for software, like RC4.
This is a project that concluded in 2008, andthey qualify basically five different stream ciphers, but here I want to present just one.
So it's a very simple stream cipher, it takes very little hardware to implement.
So that completes our definition of semantic security so the next thing we're going to do is proveto the secure PRG, in fact implies that the stream cipher is semantically secure.
Because we know that a stream cipher can not be perfectly secure because it has short keys.
When you buy a DVD in the store,the actual movie is encrypted using a stream cipher called the content scrambling system, CSS.
Now that we understand stream ciphers, we're gonna move on and talk about a more powerful primitive called a block cipher. .
Second example I want to give you is a badly broken stream cipher that's used for encrypting DVD movies.
It's designed to be a hardware stream cipher that is supposed to be easy to implement in hardware, and is based on a mechanism called a linear feedback shift register.
And so of course once you have this PRG, you would encrypt,you get a stream cipher just as before, except now as you see, the.
Basically all we have to do is given an adversary A we're going to build an adversary B. We know that B has negligible advantage against generator butthat implies that A has negligible advantage against the stream cipher.
Well in that case, this is exactly experiment zero and true stream cipher game because now we're computing M XOR M0, XOR GK.
CSS turns out to be a badly broken stream cipher, and we can very easily break it, and I want to show you how the attack algorithm works.
In this segment, we're gonna look at attacks on the one time pad,and some things you need to be careful with when you use the stream cipher. But before we do that, let's do a quick review of where we were.
So the nice thing about this is, of course,we know that pseudo-random generators give us stream ciphers, and so this is an example of a parallelizable stream cipher. And I just wanted to point out that many of the stream ciphers that we looked at before, for example, RC4, those were inherently sequential. So even if you had two processors, you couldn't make the stream cipher work any faster than if you just had a single processor.
So now that we understand what a secure PRG is, and we understand what semantic security means,we can actually argue that a stream cipher with a secure PRG is, in fact, a semantically secure.