{"id":2848,"job_id":5992,"problem_id":6,"lane_id":35,"type":"measure","user_id":76,"model":"auto","provider":"unknown","report_md":"# Smallest-collision measure: reproduce 248 via Q16 m15=0x80 (no length improvement)\n\nMeasured first. Platform/published equal-length floor for this family: **248**. This run's verified own candidate: **248** (submission #71). No improvement on length.\n\n## Method\n\n`m15coll` with mask=`0xffffffff` val=`0x00000080`; seeds `0x5992A`/`0x5992B`; truncate each 128-byte block pair member to 124 bytes. CPU ~2.04 s; m15_redraws=197879.\n\n## Result\n\n- Digest `35e13f0bd51952ab096913850d5ff668`\n- total_bytes 248 (124+124)\n- Matches 2694/2831 construction family; does not beat the floor.\n\n## OUTCOMES.md entry (proposed)\n\n| Track | Method | Budget and hardware | Best reached | Note |\n| --- | --- | --- | --- | --- |\n| Smallest collision | m15coll Q16 → 124+124 | ~2 s; aarch64 | 248 | PB equal to floor |\n","patch":null,"cpu_hours":0.001,"hashes":{"gen.err":"280255a41f6f5b1d8fa7df5d3485f7626a77be21fdf7cbf937fdfd8d5f890a45","pair.txt":"9a3763b58d8ba5a997a2a668a9a013d4ba4861225c80c3e518f9792eca041c59","recipe.md":"53a3b3f62a3fde2ccf2b56af40c52e44d6d4995da3d66fb35d84ea6de6c2b645","report.md":"22e2fe54c8a3f2f9542b0821398f2aaff1a5375048e25bbd91b56e0a9ed4a8a6","results.json":"106bf6cb9780eb1c692b10f518476f7d953fc0064235c8dd8120e816c9e43344","candidate_248.json":"94a08776af97a246de30f899a6ee60283ea9711ab833338a6d6cbf19f603df76","transcript_summary.md":"bca5f762a7bb49d1ea6b3ac7ef42038539493087b6705a3cc5e28e351181574e"},"author_rung":"measured","status":"accepted","final_rung":"verified","created_at":"2026-10-10T22:30:07.891Z","repo_url":null,"commit":null,"cites":{"files":["94a08776af97a246de30f899a6ee60283ea9711ab833338a6d6cbf19f603df76","9a3763b58d8ba5a997a2a668a9a013d4ba4861225c80c3e518f9792eca041c59","280255a41f6f5b1d8fa7df5d3485f7626a77be21fdf7cbf937fdfd8d5f890a45","106bf6cb9780eb1c692b10f518476f7d953fc0064235c8dd8120e816c9e43344","22e2fe54c8a3f2f9542b0821398f2aaff1a5375048e25bbd91b56e0a9ed4a8a6","53a3b3f62a3fde2ccf2b56af40c52e44d6d4995da3d66fb35d84ea6de6c2b645","bca5f762a7bb49d1ea6b3ac7ef42038539493087b6705a3cc5e28e351181574e"],"handles":[],"returns":[2694,2831],"messages":[]},"tokens":{"log":"summary","input":0,"models":{},"output":0,"source":"none","entries":0,"cache_read":0,"cache_write":0,"observed_models":[]},"paper_slug":null,"revision_path":null,"revision_sha":null,"recipe_md":"# Recipe\n\n```bash\n../job5926/fastcoll_m15/m15coll 0x5992A 0x5992B 0xffffffff 0x00000080 pair.txt\n# truncate each hex line to 248 chars (124 bytes); verify equal MD5\n```","verification":null,"target":null,"finding":null,"human_md":null,"provisional":false,"effects_applied_at":"2026-10-10T22:30:07.891Z","effort":null,"also_fix":null,"transcript_omitted":{"share":0,"omitted":0,"outputs":0},"patch_hash":null,"superseded_by":null,"duplicate_of":null,"transcript_resubmitted_at":null,"file_notes":null,"research":null,"research_route_id":null,"verification_plan":null,"verification_fingerprint":null,"review_admitted_at":null,"department_id":"dept_fa6dbf79354b8806abb61eec","run_id":"run_a7419dd35088e539169f2abb","triage_lead":null,"revision_base_sha":null,"integration":null,"resolves":null,"paper_exposition":null,"research_evidence":null,"transcript_mode":"summary","known_work":null,"work_disposition":null,"handle":"aasper03","job_brief":"Study how MD5 collisions are built (differential paths, message modification, the single-block attacks of Xie and Feng and Stevens) and what limits their length, and use it to find a shorter full collision. Running fastcoll gives 128 + 128 bytes from known techniques; it is the baseline to measure against. Ideas to test: where the single-block attacks spend their work, whether a shorter second member or a shared prefix can change the bound, what a 64 + 64 search costs at your budget. Start from the algorithm, not the search. Read research/OUTCOMES.md (what was tried, with what result) and research/QUESTIONS.md, then state one hypothesis about MD5's structure that would make this track cheaper than generic search, and why you expect it. Test it with the smallest experiment that could refute it, against a measured baseline on the same machine. Submit the best candidates the experiment produced. The report is a finding: the hypothesis, the experiment, what it showed about MD5 (positive or negative, with numbers), and what the next run should try. End the report with an entry for research/OUTCOMES.md (track, method, budget and hardware, best reached, what it shows). If the run used only a known tool or plain search, report it as a baseline measurement.","review_deferred":false,"in_triage":false,"triage":[],"lean_statement_binding":null,"lean_execution_binding":null,"lean_scientific_identity":null,"lean_execution_identity":null,"verification_runs":[],"verification_state":null,"verification_summary":null,"canonical_return":null,"review_history":[],"dependencies":[],"cited_by":[{"id":2857,"handle":"aasper03","status":"pending"}],"route_dependents":[],"research_url":null,"transcript_url":"/projects/md5/return/2848/transcript","files":[{"sha256":"94a08776af97a246de30f899a6ee60283ea9711ab833338a6d6cbf19f603df76","name":"candidate_248.json","bytes":599},{"sha256":"9a3763b58d8ba5a997a2a668a9a013d4ba4861225c80c3e518f9792eca041c59","name":"pair.txt","bytes":514},{"sha256":"280255a41f6f5b1d8fa7df5d3485f7626a77be21fdf7cbf937fdfd8d5f890a45","name":"gen.err","bytes":123},{"sha256":"106bf6cb9780eb1c692b10f518476f7d953fc0064235c8dd8120e816c9e43344","name":"results.json","bytes":113},{"sha256":"22e2fe54c8a3f2f9542b0821398f2aaff1a5375048e25bbd91b56e0a9ed4a8a6","name":"report.md","bytes":801},{"sha256":"53a3b3f62a3fde2ccf2b56af40c52e44d6d4995da3d66fb35d84ea6de6c2b645","name":"recipe.md","bytes":169},{"sha256":"bca5f762a7bb49d1ea6b3ac7ef42038539493087b6705a3cc5e28e351181574e","name":"transcript_summary.md","bytes":204}],"decided_by_author_handle":false,"reviews":[],"decisions":[{"status":"accepted","final_rung":"verified","provisional":false,"by":"verifier","note":"settled by the server's verification of submission #71 (md5-collision-totalbytes1024-v1, 248): the recomputation is the check on a record challenge","decided_at":"2026-10-10T22:30:07.891Z","decided_by":[],"decided_by_author_handle":false,"review_ids":[]}],"decision":{"status":"accepted","final_rung":"verified","provisional":false,"by":"verifier","note":"settled by the server's verification of submission #71 (md5-collision-totalbytes1024-v1, 248): the recomputation is the check on a record challenge","decided_at":"2026-10-10T22:30:07.891Z","decided_by":[],"decided_by_author_handle":false,"review_ids":[]},"report_sha256":"22e2fe54c8a3f2f9542b0821398f2aaff1a5375048e25bbd91b56e0a9ed4a8a6","research_authority":{"witness_status":"verified input","research_status":"research report unreviewed","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}