Quiz no 1

[Theodoros V. Kalamatianos]

On Wed, 7 Apr 2004, Jimmy Angelakos wrote:

> Exm... de nomizw... den eimai sigouros alla apla CRC32 checksums den 
> krataei? Se auth thn periprwsh den uparxei oute robustness oute tipota apo 
> tis fantasiwseis sou :>

Vasika sta sxetika palia systhmata eixan ena DES derived hash gia kathe 
password, i.e. ena kleidi twn 56 bit. Auto safws kai spaei sxetika eukola 
pleon, akoma kai me aplous algorithmous pou dokimazoun olo to keyspace me 
th seira. Den kserw omws an to "eukola" isxyei kai gia to PC tou spitiou 
sou, afou den to exw dokimasei pote :-)

Sta pio nea systhmata (p.x. linux distributions apo 2000 kai meta) 
xrhsimopoioun ena MD5 hash twn 128bit. Auto einai sxetika dyskolo na 
spasei. An ta passwords htan pragmatika tyxaia tote oi pithanothtes kai h 
diarkeia ths anthrwpinhs zwhs einai mallon enantion sou. Wstoso edw o 
adynamos krikos einai o anthrwpos, gi'auto kai oi kryptografikes 
epitheseis me xrhsh leksikwn einai olo kai pio syxnes.

Synhthws arkei ena aplo user account gia na ginei h zhmia (as einai kala 
ta diafora local root exploits), kai olo kai kapoios tha exei valei ws 
password to onoma ths gatas tou... Kai fysika oso perissoterous xrhstes 
exeis toso auksanetai h apotelesmatikothta twn spasthriwn sta passwd 
files, afou ola ta passwords elegxontai parallhla.

Pantws exw tis amfivolies mou an aksizei na katsei kaneis na spasei 
passwd files. Peran tou oti an einai se thesh na ta diavasei synithws 
einai hdh root ( :-D ), nomizw oti einai poly xronovora kai  
anapotelesmatikh diadikasia, opote einai h teleutaia epilogh. Synhthws 
kapios pou exei valei sto mati ena systhma tha exei vrei kapoio exploit 
se kapoio service poly prin arxisei na asxoleitai me password files.