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The crypto industry is discussing a high-profile precedent as researcher Giancarlo Lelli received a reward of 1 BTC from Project Eleven for successfully cracking a 15-bit ECC key on a quantum computer. While some see this as the beginning of the end for classical encryption, Adam Back has led the camp of skeptics, stating that behind the loud headline lies ordinary statistics.
Lelli used a cloud-based quantum computer and a modified Shor's algorithm to derive the key. Project Eleven highlights the progress over the past seven months - the complexity of cracked keys has increased from 6 to 15 bits, a 512-fold jump.
By their logic, breaking Bitcoin becomes merely a matter of engineering refinement.
Why Bitcoin pioneer Adam Back isn't worried about the 15-bit key breach
The head of Blockstream, Adam Back, dismissed the claim entirely. According to him, the researcher did not solve the problem using a quantum method such as discrete logarithm computation, but simply checked outputs classically that are indistinguishable from noise.
Back agrees with the explanation that Lelli's method is equivalent to simple guessing. At such a small key size of 15 bits, the probability of success through brute force is so high that the involvement of a quantum computer becomes an expensive decoration.
Adam Back remains confident regarding quantum resistance. His view as of April 2026 is that quantum machines will first break state secrets and banking systems, not Bitcoin.
The criticism was supported by former Bitcoin Core developer Jonas Schnelli, who provided specific numbers: out of a total keyspace of 32,497 possibilities, the researcher tested around 20,000. "This is a 50% probability, like flipping a coin. Quantum computing contributed nothing useful here", Schnelli concluded.
As of now, the "first-ever quantum hack" is regarded by experts as more of a marketing move than a technical breakthrough. Back maintains that as long as Bitcoin keys remain 256 bits long, such experiments remain nothing more than a sandbox exercise.
Dan Burgin
U.Today Editorial Team
