Aboriginal Art

Pictures from an exhibition on aboriginal art at Vogüé Castle, France. Shot with a Nexus One.

Fun with diagonalization

No more loops, embrace the future with recursive self-modifying code and diagonalization. In the following code snippet, we show how to replace loops like ‘while E do C’ with only ‘if’ and ‘eval’ statements:


// expects stmt == 'if(expr) { command }'
function Z(stmt) {
    start = stmt.indexOf('(')+1;
    end = stmt.indexOf(')');
    expr = stmt.substr(start, end-start);

    start = stmt.indexOf('{')+1;
    end = stmt.lastIndexOf('}');
    command = stmt.substr(start, end-start);

    out = 'if ('+expr+') {'+command+'; stmt=\'if('+expr+') {'+command+'}\'; eval(Z(stmt))}';
    return out;
}

i = 3;

// the following line is equivalent to while(i>=0) { alert(i); i-- }:
eval(Z('if(i>=0) { alert(i); i-- }'))



Read more about diagonalization and its use by Cantor and Gödel here.

UPDATE: a nicer code snippet by Matt Kaczmarek below.


special = "/**/"
function Z (stmt){
    stmt = stmt.replace (special, "\'" + stmt + "\'");
    return stmt;
}

i = 3;

// the following line is equivalent to while(i>=0) { alert(i); i-- }:
eval(Z('if(i>=0) {alert(i); i-- ; eval(Z(/**/))}'));

Newsflash: clever tricks have never been clever

“DOS applications were rarely well behaved in terms of using existing system resources since they typically ran one at time. Developers often used tricks or even existing bugs in the OS or processors in clever ways to get more memory or prevent running of unlicensed copies. Windows was intended to enable multiple applications to run at the same time, so it was difficult to support running existing applications while isolating them so their clever tricks would not corrupt other applications.”
Tandy Trower [technologizer.com]

And that was 25 years ago. Ouch.

US Domination over Security Conferences

(UPDATE: now with NDSS data)

Looking at the program committees of a few top-ranking security conferences, you have to stop and think “wow, there’s a lot of American people in there” (I am referring to people working in the US, not necessarily their nationality). Just to name a few:

  • ACM CCS 2010: 39 out of 54 PC members in the US (72.2%)
  • Internet Society NDSS 2010: 31 out of 37 (83.8%)
  • IEEE S&P 2010: 42 out of 49 (85.7%)
  • Usenix Security 2010: 26 out of 28 (92.9%)

And an approximation of the similarity of program committees (only based on last names):

ndss & s_p : ['Feamster', 'Traynor', 'Shacham', 'Ateniese', 'Kirda',
'Smith', 'Stavrou', 'Barth', 'Backes', 'Kruegel', 'Borisov', 'Kohno',
'Brumley', 'Sion', 'Locasto', 'Reiter']
similarity: 33.33%

ndss & usenix : ['Traynor', 'Shacham', 'Provos', 'Barth', 'Danezis',
'Borisov', 'Ganapathy', 'Garfinkel', 'Locasto']
similarity: 24.32%

ndss & ccs : ['Christodorescu', 'Kirda', 'Stavrou', 'Barth',
'Danezis', 'Borisov', 'Kohno', 'Ganapathy', 'Locasto', 'Cui']
similarity: 18.52%

s_p & usenix : ['Jha', 'Traynor', 'Giffin', 'Halderman', 'Shacham',
'Barth', 'Borisov', 'Locasto']
similarity: 16.67%

s_p & ccs : ['Halderman', 'Molnar', 'Waters', 'XWang', 'Stavrou',
'Barth', 'Gligor', 'Borisov', 'Kohno', 'Locasto', 'Yu', 'Kirda']
similarity: 22.22%

usenix & ccs : ['Sekar', 'Halderman', 'Gribble', 'Sailer', 'Barth',
'Danezis', 'Borisov', 'Ganapathy', 'Locasto', 'HWang']
similarity: 18.52%

.

I’m not sure how to interpret these numbers, they can mean lots of different things:

  • they might reflect the proportion of US/RestOfWorld academics working on computer security
  • or they might reflect the proportion of US/RestOfWorld academics working on software engineering (and therefore there is nothing specific to computer security)
  • causation 1: security conferences are top ranking when they have mostly US PC members
  • causation 2: top ranking conferences attract US PC members
  • what else?

1998 has called and they want their software back

“The need to improve current industrial software engineering practice is widely felt. To mention only a few striking examples: too many software projects fail and are canceled before completion or are not delivered on time or exceed their budget the energy spent on testing code is ever increasing and tends to represent more than half of the entire development cost, the number of errors found in complex software is ofter rather high, there is almost no software warranty whatsoever, but again and again the world is surprised by Trojan horses and security holes, etc.”

Abstract State Machines, Egon Börger and Robert Stärk, 1998