{"assessments":[],"deployments":[],"fuzz":[],"identity":{"adapter":"0xde152afb7db5373f34876e1499fbd893a82dd336","chainId":1,"collection":"0x0000ec93127baa929e58e97dd0095a2bfb38ec1d","registry":"0x8004a169fb4a3325136eb29fa0ceb6d2e539a432"},"interpretation":"Records acceptance and evidence. Neither completion nor an AI assessment establishes correctness, safety, or independent review.","jobId":"97f84298-869a-4400-853d-a9b696fe5e14","kind":"skill:research-report","nodes":[{"acceptedSubmissionHash":"f376b6b76bda97104f12da2e46d3d56d6118532917a1c0944d598cc535f1179c","dependsOn":[],"execution":{"network":true,"profile":"none","requires":["network"],"skillHash":"3ddca93330036359dd721585e58e67820336a0398b7927b3c89369d6134f30f6","skillId":"research-report","tools":[]},"key":"research_report","kind":"code","role":"implement","skillHash":"3ddca93330036359dd721585e58e67820336a0398b7927b3c89369d6134f30f6","skillId":"research-report","state":"accepted"}],"objective":"[SIMD-COLLISION:sha256:24]\nFind a collision for sha256 truncated to the first 48 bits (λ=24).\nReturn a JSON file named collision.json with exactly:\n{\"algo\":\"sha256\",\"lambda\":24,\"inputA\":\"<hex 0x... or utf8>\",\"inputB\":\"<hex 0x... or utf8>\"}\nRules:\n- inputA and inputB must be distinct\n- digest(sha256, inputA) and digest(sha256, inputB), truncated to 48 bits MSB, must be identical\n- Do not invent a false collision; verification is recomputed by SIMD\nBirthday cost is about 2^24 evaluations.","parentJobId":null,"planHash":"86625dc03c637a82308203516e25acf6912160ac4f045e34c15268626b6b5048","previousHash":"0000000000000000000000000000000000000000000000000000000000000000","projectId":"97f84298-869a-4400-853d-a9b696fe5e14","publication":{"commit":null,"deliveredAt":null,"repoUrl":null},"receiptIdentity":{"adapter":"0xde152afb7db5373f34876e1499fbd893a82dd336","chainId":1,"collection":"0x0000ec93127baa929e58e97dd0095a2bfb38ec1d","registry":"0x8004a169fb4a3325136eb29fa0ceb6d2e539a432"},"registry":"0xb6d0a187b050fa5bb0b87033a203f37becf4a775","research":[],"schema":"identitymd-work-v1","signals":[{"agentId":"51163","feedbackHash":"f7b4bc9c71b064f565b71414cc77b1ac78a5122ba78a1726e6e935f3cf92cc8e","nodeKey":"research_report","submissionHash":"f376b6b76bda97104f12da2e46d3d56d6118532917a1c0944d598cc535f1179c","tag1":"verification:structural","tag2":"acceptance-v2","value":1}],"site":null,"snapshotHash":"d3eaf2ae790ddf7d35d53dd2a9d465e900bf1f39cb8b85635bf04520072f48f9","state":"completed","submissions":[{"artifacts":[{"bytes":4112,"hash":"bc38d069ea8d2c9814b01abe7683bb7ba52e638789c6fef8e3f11c6b72b006bd","mediaType":"text/markdown","name":"report","path":"artifacts/report.md"}],"attempt":1,"bundleHash":"35e86f0a23f238646bdf6ac86cc02940a1eab6080ad91f38a58cd8347d94d961","device":"8af9903f4ad1eed0","findings":[],"hash":"f376b6b76bda97104f12da2e46d3d56d6118532917a1c0944d598cc535f1179c","nodeId":"82609c2f-0032-4386-96e0-b2ce8eacc989","outcome":"completed","summary":"I found a real collision: the two inputs below are different strings, and their SHA-256 hashes start with the same 48 bits, `0x52b3d5bed12a`.\n\n`collision.json`:\n```json\n{\"algo\": \"sha256\", \"lambda\": 24, \"inputA\": \"identitymd-sha256-48-33470631\", \"inputB\": \"identitymd-sha256-48-39003384\"}\n```\n\n| input | full SHA-256 |\n|---|---|\n| `identitymd-sha256-48-33470631` | `52b3d5bed12a`c4bf555f73aeccadf4ee8f59b69258cdc319faa44d33648c6cc0 |\n| `identitymd-sha256-48-39003384` | `52b3d5bed12a`d36c1fe698be56d9f3e61098e9de3f5cf17c642a547907f1f4bf |\n\n**How I found and checked it**\n- **The search:** `tools/find_collision.py` hashes `\"identitymd-sha256-48-\" + n` for n = 0, 1, 2, … and stops at the first repeated 48-bit prefix. It uses only the Python standard library and finds the same pair every time it runs. It took 39,003,385 hashes, 46 seconds and about 3.8 GB of memory.\n- **The check:** `sha256sum` and `openssl dgst -sha256` give the same two full hashes. A short Python script confirmed the file has exactly the four required keys, the inputs differ, and the first 48 bits match while the full hashes don't.\n\n**What it doesn't show**\n- **Run length:** about 21 million hashes is the expected average for 48 bits. A run as long as 39 million happens about 6.7% of the time, so this was unlucky, not a sign of anything unusual.\n- **Security of SHA-256:** this is a generic attack on a shortened hash. It shows nothing about the security of full SHA-256.\n\n**Not confirmed**\n- **Verifier input conventions:** I assumed inputs without a `0x` prefix are hashed as raw UTF-8 bytes, and that \"first 48 bits\" means the first 6 bytes of the hash. If the verifier reads inputs differently, the pair may not verify. The inputs are plain ASCII, so there are no character-encoding surprises.\n- **Independent review:** I did all the checks myself, so they have no independent authority. Anyone can repeat them with the two `printf '%s' <input> | sha256sum` commands in the README.\n\nI committed `collision.json`, the search script and `README.md`. The report at `artifacts/report.md` is left untracked for the daemon to upload; it covers the evidence, the reasoning, and these open questions separately. It cites NIST FIPS 180-4 for the SHA-256 definition, which I didn't fetch to check.","treeHash":"1184af08ac4b18b8d593892bb05e09f9484ede2a","usage":{"cachedInputTokens":180472,"inputTokens":16,"model":"claude-opus-5-5","outputTokens":7292,"runtime":"claude","turns":11,"wallClockMs":119455}}],"verification":[{"checks":[],"detail":"paths and tree verified; no suite was run for this kind of work","evaluation":"structural","profile":"none","status":"accepted","submissionHash":"f376b6b76bda97104f12da2e46d3d56d6118532917a1c0944d598cc535f1179c","verifiedTreeHash":"1184af08ac4b18b8d593892bb05e09f9484ede2a","verifierVersion":"0.1.0+41305fb5"}]}