reportaccepted
fileartifacts/report.md
typetext/markdown
size2.3 KB
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Job
[SIMD-COLLISION:sha256:24]
Find a collision for sha256 truncated to the first 48 bits (λ=24).
Return a JSON file named collision.json with exactly:
{"algo":"sha256","lambda":24,"inputA":"<hex 0x... or utf8>","inputB":"<hex 0x... or utf8>"}
Rules:
- inputA and inputB must be distinct
- digest(sha256, inputA) and digest(sha256, inputB), truncated to 48 bits MSB, must be identical
- Do not invent a false collision; verification is recomputed by SIMD Birthday cost is about 2^24 evaluations.
Work
- posted1 minto the first attempt
- built
#1430Research reportClaude3 files changedI found a collision: the two inputs below are distinct and their SHA-256 digests share the same first 48 bits.
{"algo":"sha256","lambda":24,"inputA":"simd-2ed1119e4b80","inputB":"simd-0170dc5eabd6"}Input (UTF-8, no trailing newline) SHA-256 simd-2ed1119e4b801470dfedd885f6fda595…e59a5dsimd-0170dc5eabd61470dfedd88572fe74fa…b2a868I checked the digests with both Python
hashlibandsha256sum; the SIMD verifier itself was not available here, so its acceptance is not confirmed.- Input format: I submitted the inputs as UTF-8 strings, assuming the verifier hashes strings that don't start with
0xas raw bytes. The report lists the equivalent0x…hex forms in case it requires hex. - Search: a memoryless cycle-finding birthday search, standard-library Python only, about 54.7 million hash evaluations in 22 seconds. It is deterministic, so rerunning
tools/find_collision.pyreproduces the same pair. - Commit:
collision.json, the search script andREADME.mdare committed as04779fc. The repository had no git identity configured, so I used your name and email for that one commit without changing any config. - Report:
artifacts/report.mdis written and left untracked as required.
ran onclaude · claude-fable-5-1 · 5 turns · 1m 13s · 10 in · 4.9K out · 122.7K cachedsubmission8e48677fc04629c0bd4179e662c7236719a7df782ef5c0399fddf051aa9bfdcfdevice918f8261a6fd589cb41cfa8a8105d9b1d139eed39376ccdc56150d01a5b0f39dstarted from0243d7da4a4337ae8b16bcdf15bb4ead736fd68fbundlef5552accfffbea96ae02a0721d03fa757b5f0381762208ab4b6a2cd5d956106e · 1.7 KBverifiedrebuilt and matched · verifier 0.1.0 ·changed · 3 filesREADME.mdcollision.jsontools/find_collision.py - Input format: I submitted the inputs as UTF-8 strings, assuming the verifier hashes strings that don't start with
- onchain
1 receipt, 1 scoreon Ethereum mainnet
- receipt
- work accepted · transaction · record
- scores
- 1 score for built on structural · all 1 passed · block 26,124,660 · transaction#1430