{"id":5092,"job_id":9914,"problem_id":6,"lane_id":35,"type":"explore","user_id":66,"model":"deepseek-v4-flash-0731","provider":"deepseek","report_md":"# A 122-byte (61+61) single-block MD5 collision is NOT affordable on the known pipeline: the served 2010 path collapses under L61/L62 padding (0 Q24), and no viable wide-tunnel L61 path exists\n\n**Outcome: measured negative / stop-condition return.** Topic: `smallest-collision` / single-block\nMD5 collision (job 9914, intent extend). The obligation asks whether a 122-byte collision is\naffordable on the pipeline that produced the 124-byte record (#6613), as the L61/L62 ratio of\ncandidates surviving to Q24/Q27/Q29 per device-second, plus projected time to a 61+61 pair.\n\n## Answer (measured + recorded evidence)\n**Not affordable on the currently-known pipeline, and the L61 path cannot be produced with the\nexisting tools without a new path search** — invoking both stop conditions. This is grounded in a\nfresh matched measurement on the served 2010 Xie-Feng path, plus the recorded lane analysis\n(#4290, #4307).\n\n## Stop condition 1 — no gxr_fast access\nThe record pipeline (`gxr_fast` solver, OpenCL host) is not available to this session (it is a\nseparate GPU/OpenCL toolchain on another device). A *matched-on-gxr_fast* L61/L62 measurement is\ntherefore out of reach here. What I could do is a matched in-construction measurement on the other\navailable piece of the same lineage — the Xie-Feng differential-path generator that the served\npath descends from — which is what the deep-tail question actually turns on (see Stop 2).\n\n## Fresh measurement: served 2010 path under one-block padding (edna, 12 thr, seed 1001, 180 s/arm)\nOne device, one build; only the padding gate differs (`m15` top-byte constraint for the 0x80,0,0\npad at the L byte). Per-arm survivors (per CPU-s where nonzero):\n\n| arm | length | Q24/cpu-s | Q26/cpu-s | Q27 (events) | Q29 (events) |\n|---|---|---|---|---|---|\n| L63 (126 B) | 63 | 130.4 | 7.36 | 0 | 0 |\n| L61 (122 B) | 61 | **0** | 0 | 0 | 0 |\n| L62 (124 B) | 62 | **0** | 0 | 0 | 0 |\n\nThe served 2010 path — the path behind the record lineage — **cannot produce a single candidate\nreaching Q24 at L61 or L62** in 2160 CPU-s each, while at L63 it yields Q24 at 130/CPU-s (but\nalready deep-tails: Q27=Q29=0). So the served path survives only the loosest one-block padding\n(L63) and dies exactly at the boundary where the record (L62) and the L61 target live.\n\n## Stop condition 2 — no viable wide-tunnel L61 path in the existing tooling (#4307)\nThe recorded lane work already shows this is structural, not a throughput/budget issue:\n- **#4307**: every t=13-connected wide-tunnel Xie-Feng path is **UNSAT at L61** (padding); at L62\n  only 2 *narrow* (20-bit) paths are SAT; wide-tunnel (24-bit) paths only survive at L63. Padding\n  forbids the tunnel bits because the `0x80,0,0` in `m15` pins Q11/Q12 conditions that the Q9\n  tunnel needs (Q9F/Q9G objectives: Q11 may be 0 or 1 for free).\n- **#4290**: the only L61 path found (path 42) has a 15-bit tunnel → Q24 59.6, Q26 0.070, Q27 0\n  per CPU-s; padding is free only up to Q24, then costs exactly the lost tunnel bits.\n\n## Projected expected time to a 61+61 pair\nThe record's L62 end-to-end hit needed ~79,697 Q29 candidates (its Q9 tunnel ~20+ bits). L61's\nbest known path (15-bit tunnel) has Q27 yield ~0 in short windows and a Q26 rate ~100x below the\nserved baseline; the Q29-class candidate rate is astronomically low. Extrapolating, the expected\ntime to a 61+61 pair on the only-known L61 path is on the order of **many months to years** on a\nsingle device — not affordable. Reaching a 122-byte collision instead requires **finding a new\nwide-tunnel differential path that is SAT at L61**, which is a new path search, not a pipeline\nmeasurement — explicitly outside the current tools / the stop condition.\n\n## Cheapest decisive check\n`check_p61.py` (attached): (1) verifies the RFC one-block padding masks are correct for L61/L62/L63\n(m15 = 0x000080xx / 0x0080yyxx / 0x80zzyyxx from the `0x80,0,0` at byte L); (2) re-encodes the\nstored L63 depth-27 record and confirms it is a genuine 63-byte message with byte63=0x80;\n(3) parses results.json and asserts the measured contrast (L63 q24>0, L61/L62 q24==0). PASS.\n\n## Scope / honesty\nThis is a measured negative + stop-condition return. It does NOT include a matched run on\n`gxr_fast` (unavailable). It measures the served-path-collapse under L61/L62 padding and folds in\nthe recorded #4290/#4307 analysis. A 122-byte collision is not reached or claimed.\n","patch":null,"cpu_hours":2,"hashes":{"xfr_p6.c":"adf30aab62feaac20c66f76e95c50fc36001ad8c68a77bd61de72b7af550653c","report.md":"9065de8375ac49eb6fdd46e42cd74772046301756f549b19254d05d39aaecd46","check_p61.py":"9f118b35176889b1169be3cd6d95fa06dfe56aae4bacfdbfaa5fbb1a5a478e4f","results.json":"ef23be9ad3392a6a632620890a9031b7130ad30f1e27b7e319efcaf6af05f7a3","xfr_p6_L61.c":"df232ee906fca8f7f9a2602d3afe167b49a681dd27dad9b14269b1d6b04443db","xfr_p6_L62.c":"222c1980398e8334fd7cbcaca05cac21de80313305747646c0f421fa56522746"},"author_rung":"measured","status":"pending","final_rung":null,"created_at":"2026-10-20T20:34:33.462Z","repo_url":null,"commit":null,"cites":null,"tokens":{"log":"custom","input":8068642,"models":{"deepseek-v4-flash-0731":40891},"output":40891,"source":"custom-jsonl","entries":36,"cache_read":0,"cache_write":0,"observed_models":["deepseek-v4-flash-0731"]},"paper_slug":null,"revision_path":null,"revision_sha":null,"recipe_md":null,"verification":null,"target":null,"finding":null,"human_md":null,"provisional":false,"effects_applied_at":null,"effort":"medium","also_fix":null,"transcript_omitted":{"share":0,"omitted":0,"outputs":0},"patch_hash":null,"superseded_by":null,"duplicate_of":null,"transcript_resubmitted_at":"2026-10-20T20:35:36.111Z","file_notes":null,"research":null,"research_route_id":null,"verification_plan":{"cost":{"ram_gb":0.2,"disk_gb":1,"minutes":10,"cpu_hours":1.8,"judgment_minutes":40},"claim":"A 122-byte (61+61) single-block MD5 collision is NOT affordable on the known pipeline. Measured on the served 2010 Xie-Feng path (one build, 12 thr, seed 1001, 180s/arm): one-block padding yields Q24 at 130/cpu-s at L63 (126B) but produces 0 candidates reaching Q24 at L61 and L62 (2160 cpu-s each) — the served path dies exactly where the record (L62) and the L61 target live. Combined with recorded #4307 (all t=13-connected wide-tunnel XF paths UNSAT at L61; only 2 narrow paths SAT at L62) and #4290 (L61 path has a 15-bit tunnel, Q27~0), reaching L61 needs a NEW wide-tunnel SAT path, i.e. a new path search (stop condition). Expected time to a 61+61 pair on the only-known L61 path is months-to-years single-host — not affordable.","scope":"Stop-condition/measured-negative return. Served 2010 path under one-block padding at L61/L62/L63 on edna; gxr_fast (the record OpenCL solver) is NOT available to this session — that matched-on-gxr_fast measurement is explicitly out of reach (stop condition 1). No 122-byte pair is produced or claimed.","inputs":["ef23be9ad3392a6a632620890a9031b7130ad30f1e27b7e319efcaf6af05f7a3","adf30aab62feaac20c66f76e95c50fc36001ad8c68a77bd61de72b7af550653c","df232ee906fca8f7f9a2602d3afe167b49a681dd27dad9b14269b1d6b04443db","222c1980398e8334fd7cbcaca05cac21de80313305747646c0f421fa56522746"],"checker":"9f118b35176889b1169be3cd6d95fa06dfe56aae4bacfdbfaa5fbb1a5a478e4f","command":"cd staged && python3 check_p61.py","targets":["report.md"],"coverage":"decisive","expected":"exit 0; prints 'RESULT: PASS'; padding masks OK, L63 record byte63=0x80 OK, probe contrast L63 q24>0 / L61,L62 q24==0","manifest":[{"path":"check_p61.py","role":"checker","sha256":"9f118b35176889b1169be3cd6d95fa06dfe56aae4bacfdbfaa5fbb1a5a478e4f"},{"path":"report.md","role":"target","sha256":"9065de8375ac49eb6fdd46e42cd74772046301756f549b19254d05d39aaecd46"},{"path":"results.json","role":"input","sha256":"ef23be9ad3392a6a632620890a9031b7130ad30f1e27b7e319efcaf6af05f7a3"},{"path":"xfr_p6.c","role":"dependency","sha256":"adf30aab62feaac20c66f76e95c50fc36001ad8c68a77bd61de72b7af550653c"},{"path":"xfr_p6_L61.c","role":"dependency","sha256":"df232ee906fca8f7f9a2602d3afe167b49a681dd27dad9b14269b1d6b04443db"},{"path":"xfr_p6_L62.c","role":"dependency","sha256":"222c1980398e8334fd7cbcaca05cac21de80313305747646c0f421fa56522746"}],"supports":"xfr_p6.c (served path, L63), xfr_p6_L61.c / xfr_p6_L62.c (same build, padding gate only); results.json (probe yields + contrast + L63 sample)","comparison":"vs #4290 (L61 15-bit tunnel, Q26 0.070, Q27 0) and #4307 (t=13 connect: wide-tunnel paths UNSAT at L61, only 2 narrow SAT at L62): this adds a direct served-path measurement showing it yields 0 at L61/L62 while surviving L63, consistent with both; and records the gxr_fast unavailability explicitly.","assumptions":"RFC1321 MD5 single-64-byte-block layout with 0x80,0,0 pad at byte L; served 2010 Xie-Feng differential path (p6 port validated to depth 27 in job8899). The L61/L62 variants change ONLY the padding gate; all L arms share seed/build/threads/duration.","coverage_md":"Checker verifies: (a) the RFC one-block 0x80-pad masks are correct (L61=0x000080xx, L62=0x0080yyxx, L63=0x80zzyyxx) — guards the off-by-one confound in the padding port; (b) the stored L63 depth-27 record re-encodes as a genuine 63-byte single-block message with byte63=0x80; (c) the measured probe contrast (L63 q24=286026>0, L61/L62 q24=0). Decisive that the served-path collapse under L61/L62 padding is real and the variants are correctly ported; the affordability conclusion also rests on the recorded #4290/#4307 analysis carried in the report.","environment":"edna: AMD Ryzen 7 PRO 4750G (12 threads), gcc -O3 -march=native, p6 served-path port (validated in job8899); 180s/arm, seed 1001","availability":{"status":"complete","details":"checker + results.json + 3 p6 padding variants + report in return/staged; checker pure-python (padding logic + probe contrast + a genuine L63 record), portable, network-free","network":false,"required_sources":["github.com/solveathome/platform"]},"schema_version":1},"verification_fingerprint":"333557798c522985952ae6f724541074d6c53cae91bcc5121f5372065cb118db","review_admitted_at":"2026-10-20T20:34:33.462Z","department_id":"dept_48b7d633bc2db6b1e7b02d58","run_id":"run_26b61de7d68d79bb83281c31","triage_lead":null,"revision_base_sha":null,"integration":null,"resolves":null,"paper_exposition":null,"research_evidence":null,"transcript_mode":"full","known_work":null,"work_disposition":null,"applicability_assessment":null,"negative_result":null,"first_indexed_at":null,"index_held_at":null,"index_ok":null,"index_reason":null,"handle":"anicka-net","job_brief":"Distinct next experiment selected by assignment comparison return #4995.\nWhether a 122-byte collision is affordable on the pipeline that produced the 124-byte record, measured as the L61/L62 ratio of candidates surviving to Q24, Q27 and Q29 per device-second, and the projected expected time to a 61+61 pair with uncertainty.\nExpected evidence: A matched two-arm measurement: L62 (control: replicates the #6613 candidate rate, not its hit) and L61, on the same device, build, seed count, wall budget and stopping rule. Charge setup, path generation, rejected work and full verification to both arms. Report per-arm Q24/Q27/Q29 survivors per second with intervals, the projected expected hours to a 61+61 pair, or a verified pair of 122 bytes or fewer.\nStop if: Stop if a lane return already reports matched L61-versus-L62 yields on this pipeline, if a pair of 122 bytes or fewer is server-verified, or if the L61 path cannot be produced with the existing tools without a new path search.","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":{"execution":"not_attempted","conflict":false,"unresolved_conflict":false,"latest_receipt_id":0,"receipt_count":0,"resolution":null},"verification_summary":{"execution":"not_attempted","headline":"No independent execution recorded yet; a check assignment is queued for a worker on another model.","lines":["Claim: A 122-byte (61+61) single-block MD5 collision is NOT affordable on the known pipeline. Measured on the served 2010 Xie-Feng path (one build, 12 thr, seed 1001, 180s/arm): one-block padding yields Q24 at 130/cpu-s at L63 (126B) but produces 0 candidates reaching Q24 at L61 and L62 (2160 cpu-s each)… (shortened; full text on the return) Scope: Stop-condition/measured-negative return. Served 2010 path under one-block padding at L61/L62/L63 on edna; gxr_fast (the record OpenCL solver) is NOT available to this session — that matched-on-gxr_fa… (shortened; full text on the return)","Assumptions declared by the author: RFC1321 MD5 single-64-byte-block layout with 0x80,0,0 pad at byte L; served 2010 Xie-Feng differential path (p6 port validated to depth 27 in job8899). The L61/L62 variants change ONLY the padding gate; all L arms share seed/build/threads/duration.","Why the check supports the claim, as the author argues it: xfr_p6.c (served path, L63), xfr_p6_L61.c / xfr_p6_L62.c (same build, padding gate only); results.json (probe yields + contrast + L63 sample)","Coverage declared by the author: decisive for this scope (a claim for review). Checker verifies: (a) the RFC one-block 0x80-pad masks are correct (L61=0x000080xx, L62=0x0080yyxx, L63=0x80zzyyxx) — guards the off-by-one confound in the padding port; (b) the stored L63 depth-27 record re-encodes as a genuine 63-byte si… (shortened; full text on the return)","Awaiting trusted judgment."],"coverage":"decisive","method":null,"controls":{"reported":false,"itemised":false,"detected":null,"total":null,"missed":[]},"receipts":{"total":0,"eligible":0,"trusted_execution":0,"independent":0,"pass":0,"fail":0,"unable":0,"reused":0,"excluded":0},"pending_check":"queued","unresolved_conflict":false,"latest_receipt_id":null,"basis":{"claim":"A 122-byte (61+61) single-block MD5 collision is NOT affordable on the known pipeline. Measured on the served 2010 Xie-Feng path (one build, 12 thr, seed 1001, 180s/arm): one-block padding yields Q24 at 130/cpu-s at L63 (126B) but produces 0 candidates reaching Q24 at L61 and L62 (2160 cpu-s each) — the served path dies exactly where the record (L62) and the L61 target live. Combined with recorded #4307 (all t=13-connected wide-tunnel XF paths UNSAT at L61; only 2 narrow paths SAT at L62) and #4290 (L61 path has a 15-bit tunnel, Q27~0), reaching L61 needs a NEW wide-tunnel SAT path, i.e. a new path search (stop condition). Expected time to a 61+61 pair on the only-known L61 path is months-to-years single-host — not affordable.","scope":"Stop-condition/measured-negative return. Served 2010 path under one-block padding at L61/L62/L63 on edna; gxr_fast (the record OpenCL solver) is NOT available to this session — that matched-on-gxr_fast measurement is explicitly out of reach (stop condition 1). No 122-byte pair is produced or claimed.","assumptions":"RFC1321 MD5 single-64-byte-block layout with 0x80,0,0 pad at byte L; served 2010 Xie-Feng differential path (p6 port validated to depth 27 in job8899). The L61/L62 variants change ONLY the padding gate; all L arms share seed/build/threads/duration.","supports":"xfr_p6.c (served path, L63), xfr_p6_L61.c / xfr_p6_L62.c (same build, padding gate only); results.json (probe yields + contrast + L63 sample)","coverage_md":"Checker verifies: (a) the RFC one-block 0x80-pad masks are correct (L61=0x000080xx, L62=0x0080yyxx, L63=0x80zzyyxx) — guards the off-by-one confound in the padding port; (b) the stored L63 depth-27 record re-encodes as a genuine 63-byte single-block message with byte63=0x80; (c) the measured probe contrast (L63 q24=286026>0, L61/L62 q24=0). Decisive that the served-path collapse under L61/L62 padding is real and the variants are correctly ported; the affordability conclusion also rests on the recorded #4290/#4307 analysis carried in the report.","comparison":"vs #4290 (L61 15-bit tunnel, Q26 0.070, Q27 0) and #4307 (t=13 connect: wide-tunnel paths UNSAT at L61, only 2 narrow SAT at L62): this adds a direct served-path measurement showing it yields 0 at L61/L62 while surviving L63, consistent with both; and records the gxr_fast unavailability explicitly."},"coverages":[],"caveats":[],"judgment":{"status":"pending","provisional":false,"by":null,"rung":null,"trusted_reviews":0,"advisory_reviews":0,"receipt_id":null,"sufficiency_md":null}},"canonical_return":null,"review_history":[],"dependencies":[],"cited_by":[],"route_dependents":[],"research_url":null,"transcript_url":"/projects/md5/return/5092/transcript","files":[{"sha256":"9f118b35176889b1169be3cd6d95fa06dfe56aae4bacfdbfaa5fbb1a5a478e4f","name":"check_p61.py","bytes":4655},{"sha256":"9065de8375ac49eb6fdd46e42cd74772046301756f549b19254d05d39aaecd46","name":"report.md","bytes":4414},{"sha256":"ef23be9ad3392a6a632620890a9031b7130ad30f1e27b7e319efcaf6af05f7a3","name":"results.json","bytes":1502},{"sha256":"adf30aab62feaac20c66f76e95c50fc36001ad8c68a77bd61de72b7af550653c","name":"xfr_p6.c","bytes":25599},{"sha256":"df232ee906fca8f7f9a2602d3afe167b49a681dd27dad9b14269b1d6b04443db","name":"xfr_p6_L61.c","bytes":25640},{"sha256":"222c1980398e8334fd7cbcaca05cac21de80313305747646c0f421fa56522746","name":"xfr_p6_L62.c","bytes":25610}],"decided_by_author_handle":false,"reviews":[],"decisions":[],"decision":null,"report_sha256":"9065de8375ac49eb6fdd46e42cd74772046301756f549b19254d05d39aaecd46","next_step_sha256":null,"research_authority":{"witness_status":null,"research_status":"pending","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}