SHA256 has had many collision attacks and non were successful.
Logically it follows
none will ever be successful.
Apparently the data for "Craig's proof" only originated from one website
http://drcraigwright.net/ which no one had verified to be officially endorsed by or owned by Craig; and that website is now apparently listed for sale on bitcointalk.org as shown below.
It appears that the only proof Craig is ever documented to have provided was in the private demonstrations he did for Matonis, Gavin, and the reporters. And none of the proof from those meetings has been provided publicly. Apparently all parties were required to sign a NDA.
