Re: computer-go: Authenticating the identity of a remote go-playing computer program

[Mika Kojo <mkojo@xxxxxxx>]

Don Dailey writes:
> Yes,  this   is  exactly  equivalent  to the    birthday paradox.  The
> protection  we   are looking for  in  the  context of  our discussion,
> however, is not a birthday paradox issue.  The characteristic we would
> desire is   that  it should  be   incredibly  difficult  to produce  a
> "tampered with" version of a SPECIFIC program.   So we are still talking
> about 2^128, not 2^64. 

True in the sense that the programmer cannot (without an effort of
order 2^128) a posteriori create a new program that matches the MD5
checksum sent to the organizers. However, she can create programs with
the same checksum a priori using birthday paradox. Of course, this may
be completely useless in this specific setting (whatever it is :)

-- 
Mika Kojo
SSH Communications Security Corp