# Archive for category Cryprography

 Pulmatehtävä? Ota yhteyttä, yritä kertoa tehtävästä selkeästi tai ota kuva tehtävän paperista. Olen hyvin varma että osan auttaa (lukio, pitkä/lyhyt)matematiikan kanssa. Voi toki kysyä kemiasta tai fyysikasta, mutta ratkaisun saaminen on vähemmän todennäköistä.

It is definitely trivial if binary is less than 3 bits long, there are no consecutive ’111’s there.

But what if binary is three bits, or longer – how to approach this question?

Small remark: all following should be considered in . Ie 1+1=0, x+x=0, 1+0=1, x+0=x,0+0=0 and so on. Field contains only {0,1}

Once again, working from example is the best. Ok, suppose we have set of equations:

Well, lets continue with finding xor

Again, we have strings encoded to hex, after decoding we get:

"KSSP"(longer string actually)
"hit the bull's eye"

Second string is sane and xored with arbitrary bits of first string we get result:

"the kid don't play", which is same size like second input, since no control characters, sane symbols only)

Here is challenge, here is solution.

There is such interesting, matasano cryptography challenge.

Lets do it, lets use for productivity Cloud.Math, nice cloud platform. You probably have to registrate there, but you will not regret it – fully fledged, very powerful mathsuite+python.. it cant get any better.

Anyway, here is solutiun to first part. And it is good to understand, that First we have string, which is represented by encoded hex bytes. each hex byte – corresponds to character. Coverting all hexes to string we get ”I’m killing your brain like a poisonous mushroom

Afterward we take this string and encode it to base64, various ways to do it.

Also, i am back and will write mostly in english from now on, and mostly about cryptography or stuff i dig in university.