Archivi categoria: Divagazioni semiserie

Il miglior firewall al mondo

  1. una cellula umana contiene 75 MB di informazione genetica.
  2. uno spermatozoo contiene la metà, cioè 37,5 MB
  3. un millilitro di sperma contiene 100 milioni di spermatozoi.
  4. in media l’eiaculazione dura circa 5 secondi e contiene circa 2,24 ml di sperma.
  5. questo significa che la produzione del membro di un uomo è di 37,5 MB * 100.000.000 * 2,24/5 = 1.687.500.000.000.000 bytes al secondo, cioè 1,6875 TB al secondo.

In altre parole un ovulo femminile sopporta un attacco di tipo DDoS a 1,5 TB al secondo e permette il passaggio di un solo pacchetto di informazione. Questo fa della donna il miglior firewall hardware del mondo.

La cattiva notizia é che quel pacchetto che lascia passare fa impallare il sistema per nove
mesi circa.

E consuma risorse di sistema per altri 20/25 anni…

The Development of the C Language

by Dennis M. Ritchie, Bell Labs/Lucent Technologies

The C programming language was devised in the early 1970s as a system implementation language for the nascent Unix operating system. Derived from the typeless language BCPL, it evolved a type structure; created on a tiny machine as a tool to improve a meager programming environment, it has become one of the dominant languages of today. This paper studies its evolution.

Read the paper: The development of the C Language

The first collision for full SHA-1

by Marc Stevens, Elie Bursztein, Pierre Karpman, Ange Albertini, Yarik Markov

SHA-1 is a widely used 1995 NIST cryptographic hash function standard that was officially deprecated by NIST in 2011 due to fundamental security weaknesses demonstrated in various analyses and theoretical attacks.

Despite its deprecation, SHA-1 remains widely used in 2017 for document and TLS certificate signatures, and also in many software such as the GIT versioning system for integrity and backup purposes.

A key reason behind the reluctance of many industry players to replace SHA-1 with a safer alternative is the fact that finding an actual collision has seemed to be impractical for the past eleven years due to the high complexity and computational cost of the attack.

In this paper, we demonstrate that SHA-1 collision attacks have finally become practical by providing the first known instance of a collision. Furthermore, the prefix of the colliding messages was carefully chosen so that they allow an attacker to forge two PDF documents with the same SHA-1 hash yet that display arbitrarily-chosen distinct visual contents.

We were able to find this collision by combining many special cryptanalytic techniques in complex ways and improving upon previous work. In total the computational effort spent is equivalent to 263.1 SHA-1 compressions and took approximately 6 500 CPU years and 100 GPU years. As a result while the computational power spent on this collision is larger than other public cryptanalytic computations, it is still more than 100 000 times faster than a brute force search.

Read the full paper: The first collision for full SHA-1