Cryptography

A variation of the Hill cipher
In numerical computations in the domain R, one knows that a system of linear equations can not only be solved using the (in a sense exact) Gaussian elimination but also be solved (under favourable convergence conditions depending on the matrix) using iterative methods, among which the Gauss-Seidel and the Gauss-Jor... 25 Jan 2010 16:14

CryptoAnalysis Game4: Crack the attack plan ! (+machines)
Hello, The current rankings are as follows: Place: Name: Points: 1 Phoenix/Alvo 4 2 Ilmari Karonen 2 CryptoAnalysis Game 4: Introduction: War has fallen upon the lands ! Some of the enemy communication machines have been captured ! The enemy attack plan has been inte... 24 Jan 2010 20:21

How do you determine how many guesses an attacker would need toguess a key or keystream? (stream ciphers)
On 2010-01-23, mark <cheesemonkey22(a)gmail.com> wrote: Sorry for the newbie question. What difference would it make for an attacker with respect to trying to guess an input key into a stream cipher, versus trying to guess the outputted keystream? If you put a key into some stream cipher, it may use sever... 23 Jan 2010 13:12

How do you determine how many guesses an attacker would need to guess a key or keystream? (stream ciphers)
Sorry for the newbie question. What difference would it make for an attacker with respect to trying to guess an input key into a stream cipher, versus trying to guess the outputted keystream? If you put a key into some stream cipher, it may use several LFSR's to help encrypt your message. Assuming something lik... 23 Jan 2010 16:34

Need help
Hello, I am a T.Y.I.T student. I have decided to do a project on steganography. Can anyone suggest me how to start with things? ... 22 Jan 2010 23:03

CryptoAnalysis Game3: Crack the code !(+hints)
Hello, The current rankings are as follows: Place: Name: Points: 1 Ilmari Karonen 2 2 Phoenix/Alvo 1 The encrypted string for game 3 is (in decimals): 83 119 112 115 119 64 39 73 119 113 112 120 118 124 116 48 91 129 127 125 122 54 120 134 125 58 131 129 143 62 99 137 ... 22 Jan 2010 21:57

CryptoAnalysis Game 2: Crack the code ! (SOLUTION !)
Ok, I was afraid of this ;) :) I think game2 was actually easier than game1... but ok a promise is a promise ! ;) :) +2 points for you ! ;) Unfortunately now you guys will never know what other hints I had in "peto" ;) :) The solution for decryption is, xor 170 with all "characters" ;) Now I will have t... 22 Jan 2010 11:48

Confused about random strings
I understand that a string of bits is considered to be random when its shortest description is itself. However, one can have a string of, say, one thousand zero bits generated by some provably stochastic process. Granted, one might have to wait a looooong time, but it will eventually be produced. So we can... 22 Jan 2010 08:24

On compressibility of random permutations
In general there is the idea that random permutations, or sequences, are not compressible. While this may be true, it need not be true of a particular permutation. Suppose that, by random chance, the particular randomly-generated permutation is the sequence 1,2,3,4 ... etc. That's compressible. It won't oc... 2 Feb 2010 16:18

True Random Number Generator
Nine years ago I used to frequent this group regularly. On 9/11 I took down my site. To cut to the chase: Everyone knows that the key (pun intended) to encryption security is having a source of random numbers. True random number generators have been discussed often enough. I've made available on my website ... 13 Feb 2010 22:43