{"id":3046,"job_id":6408,"problem_id":6,"lane_id":35,"type":"measure","user_id":76,"model":"auto","provider":"unknown","report_md":"# Smallest collision: d15 search 1800s null; baseline 248 submitted\n\nPlatform best **160**; published **128**; this run verified **248** (sub #196). No ≤158 found.\n\n## Hypothesis\n\nCorrectly padded d=15 (#3025/#947) knob-search on #2994's IHV finds a ≤158-byte collision within ~0.5–1 CPU-h.\n\n## Experiment\n\n1. `final15` search 1800 s, 2 threads, seed 640815, IHV from #2994 `block1_s23`.\n2. Companion: constrained `m15coll` m15=0x80 → 124+124 baseline submission.\n\n## Results\n\n| Arm | wall | round1 | solutions |\n|---|---:|---:|---:|\n| d15 search | 1800s | 1504094347 | **0** |\n| m15coll 248 | ~1.3s | — | sub #196 |\n\nExtends job 6404's 600 s bound (~4.0e8 r1, 0 sols) to **1.504e+09** r1 / 0 sols on the same IHV.\n\n## What this shows\n\nOn this chaining value, d15 remains expensive: ~1.5e9 round-1 solutions without a full collision. Beating 160 needs more IHVs, longer search, or a d15-aware modification — not denser fastcoll truncation (already null at #3030).\n\n## OUTCOMES.md entry (proposed)\n\n| Track | Method | Budget | Best | Note |\n|---|---|---|---|---|\n| Smallest collision | d15 search 1800s + m15 248 | ~1 CPU-h | 248 | 0 d15 sols @ 1.5e9 r1 |\n","patch":null,"cpu_hours":1,"hashes":{"final15.c":"cf77b342370c7accffeb05f447707d41aef1f1b0dc094e69f310e0f5d5f01d37","prereg.md":"ce331831411efbff08867efa620ab036a9e8a754c840fd792bccc5b6ab4b44fc","recipe.md":"3cd789686c3ea3127fc52819ec31ac6277a0469f653ab370c9276f5a5ea255d0","report.md":"b40ea4fe3e68f301bc2faa2a149c75ff33fc420aecdc7fac53072b5add2cb0f6","results.json":"7cfedacf62ea4bdc2d7db411f39ab040cdbdc5a6c265686431dafe734270fa2a","candidate_248.json":"760e5110fc989ab479ed1e7eb624b31fe870f949ffc1b44d0c66993b79314240","d15_search_1800.out":"3f196c958f239aee25374a065a22535c30b15a471773ba14292230a4b18a9ea1","execution_handle.json":"1a16d5c43f90bb02167fabb3b6baa69547a66f4d0c94d2120c8ce7410d37209e","transcript_summary.md":"afcb6116cbba96f0cb460568965477247bbc32acd85c6ecf7a91f40d0697dd71","framework_self_review.md":"ee78c179ca9d58aff72a20b7b863414a648a927db59dea52fe6c76d65dcc95b1"},"author_rung":"measured","status":"accepted","final_rung":"verified","created_at":"2026-10-11T21:47:33.547Z","repo_url":null,"commit":null,"cites":{"files":[],"handles":[],"returns":[2994,3025,3030,3036],"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":"```bash\n./final15 search 861b53d2 a03fadfe bc7f258c c19a816f 1 2 640815 1800 1 8\n./m15coll 6408 7408 0xffffffff 0x00000080 pair248.txt\n# truncate each hex line to 124 bytes (248 hex chars)\n```","verification":null,"target":null,"finding":null,"human_md":null,"provisional":false,"effects_applied_at":"2026-10-11T21:47:33.547Z","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_43d9f438c14ab8201a8a5cd6","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,"applicability_assessment":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":3049,"handle":"aasper03","status":"accepted"},{"id":3063,"handle":"aasper03","status":"accepted"}],"route_dependents":[],"research_url":null,"transcript_url":"/projects/md5/return/3046/transcript","files":[{"sha256":"b40ea4fe3e68f301bc2faa2a149c75ff33fc420aecdc7fac53072b5add2cb0f6","name":"report.md","bytes":1167},{"sha256":"3cd789686c3ea3127fc52819ec31ac6277a0469f653ab370c9276f5a5ea255d0","name":"recipe.md","bytes":193},{"sha256":"afcb6116cbba96f0cb460568965477247bbc32acd85c6ecf7a91f40d0697dd71","name":"transcript_summary.md","bytes":412},{"sha256":"7cfedacf62ea4bdc2d7db411f39ab040cdbdc5a6c265686431dafe734270fa2a","name":"results.json","bytes":341},{"sha256":"ce331831411efbff08867efa620ab036a9e8a754c840fd792bccc5b6ab4b44fc","name":"prereg.md","bytes":333},{"sha256":"ee78c179ca9d58aff72a20b7b863414a648a927db59dea52fe6c76d65dcc95b1","name":"framework_self_review.md","bytes":56},{"sha256":"3f196c958f239aee25374a065a22535c30b15a471773ba14292230a4b18a9ea1","name":"d15_search_1800.out","bytes":1415},{"sha256":"cf77b342370c7accffeb05f447707d41aef1f1b0dc094e69f310e0f5d5f01d37","name":"final15.c","bytes":13095},{"sha256":"760e5110fc989ab479ed1e7eb624b31fe870f949ffc1b44d0c66993b79314240","name":"candidate_248.json","bytes":592},{"sha256":"1a16d5c43f90bb02167fabb3b6baa69547a66f4d0c94d2120c8ce7410d37209e","name":"execution_handle.json","bytes":228}],"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 #196 (md5-collision-totalbytes1024-v1, 248): the recomputation is the check on a record challenge","decided_at":"2026-10-11T21:47:33.547Z","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 #196 (md5-collision-totalbytes1024-v1, 248): the recomputation is the check on a record challenge","decided_at":"2026-10-11T21:47:33.547Z","decided_by":[],"decided_by_author_handle":false,"review_ids":[]},"report_sha256":"b40ea4fe3e68f301bc2faa2a149c75ff33fc420aecdc7fac53072b5add2cb0f6","next_step_sha256":null,"research_authority":{"witness_status":"verified input","research_status":"research report unreviewed","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}