[p2p-hackers] another perspective on collision-resistant vs. second-preimage-resistant

[Zooko O'Whielacronx]

Suppose you receive a software package from someone else.  It could be 
in source code form or in binary form, or whatever.

Suppose you use a hash function `f', compute h = f(software), and send 
h to a friend of yours.

Now if f is a collision-resistant function, then any software package 
that your friend finds which matches h is the same software package 
that you have.

If f is not collision-resistant, even if f is 
second-preimage-resistant, then your friend might find a software 
package which matches h but which is different from the one you have.

Regards,

Zooko