Hash collisions

Hash collisions

Posted Feb 2, 2010 4:28 UTC (Tue) by nevyn (subscriber, #33129)
In reply to: Hash collisions by epa
Parent article: Security in the 20-teens

It would be quite a task to generate a hash collision that also compiles as valid C code. And doubly impossible to generate one which is valid C code and inserts the backdoor you want.

It might be "harder" but it's far from impossible. Consider the md5 CA attack from last year, they had to do:

Complying with the X.509 standard [HPFS], each of the two certificates consists of:

    * a header of 4 bytes,
    * a so called "to-be-signed" part of 927 bytes,
    * a so called "signature algorithm" field of 15 bytes,
    * a "signature" field of 131 bytes. 

...which included predicting bits of data from the above, that the victim generated, they succeeded.

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