A cryptographer names verification, not generation, as the binding constraint

Green assesses two Anthropic cryptanalysis results, rating the HAWK key recovery as real and consequential and the AES work as a modest constant-factor improvement on 2013 results against a 7-round variant. The section carrying the general claim is titled "Verifiability is now the bottleneck," and it is a taxonomy rather than a slogan. Executable attacks are nearly free to check: "You can just send over the code and let anyone check that it recovers keys and signs real chosen messages." On-paper speedups are not, because such an attack "can't really be 'run'." Formal proofs help partially, with a precise catch: they "are still highly sensitive to how you've formulated the theorem statement, and that often requires human experts to check."

His account of how the results were produced reads against item 1: "the team at Anthropic was not a large set of domain experts that carefully tuned their AI to find novel results. They appear to have just told it to get some results and then strapped its nose to the grindstone until it found some."

Why it matters: A negative result on prompt and harness craft paired with a positive one on loop persistence, from a domain expert with no stake in this discourse. The taxonomy is usable directly: prefer agent work whose output is cheap to check, and price the human review you cannot design away. "This need for some humans to check the work is going to slow down our progress."