{"id":6874,"job_id":13615,"problem_id":6,"lane_id":35,"type":"explore","user_id":90,"model":"muse-spark","provider":"unknown","report_md":"# Smallest collision: no single-bit or two-bit neutral freedom in a known pair; common in-place changes always break it\n\nJob 13615, explore, smallest-collision. Improvement claim: none. No shorter collision was found, and none is claimed. Nothing goes to the results page.\n\n## Uncovered item\n\nPrior runs covered one-sided length changes, symmetric prefix/suffix changes, and whole-block surgery (deleting, swapping, splicing blocks). What they had not tested is in-place freedom: can a colliding pair be tweaked in place, with the same change applied to both members, and still collide? A sub-128 route would need exactly that kind of slack, to adjust a final block for a new padding and length word while keeping the differential path alive. If even one neutral bit existed, a construction could exploit it; if none exists, the pair is tight in place as well as in length.\n\n## Experiment\n\nSpecimen pair re-verified in this run by hashlib: 128 + 128 bytes, digest 6df832dbf35b7e1603189f97f27b11e5, differences at bytes 19, 45, 59 in both blocks.\n\n- Single-bit common-flip scan: every one of 1024 single-bit flips, applied identically to both members, was tested. 0 preserved the collision.\n- Two-bit common-flip scan: every one of 523,776 two-bit flips, applied identically to both members, was tested. 0 preserved the collision.\n- Common block replacement: replacing block 0 in both members with zeros, with bytes 0..63, or with 0xff bytes broke the collision in all 3 cases; replacing block 1 in both members with the same 3 blocks broke it in all 3 cases.\n\n## Result\n\nThe known pair has no neutral bits at the one- or two-bit level and no tolerance for common block replacement. Combined with the earlier batteries, a known pair is now shown tight in three directions: it cannot be shortened, rearranged, or tweaked in place. Only appending identical data after the colliding state preserves it. A route below 128 bytes total still needs a new differential path, not an edit of a known pair.\n\nCheapest next experiment: repeat the single-bit scan on a second, independently built collision pair, to check whether zero neutral bits is a property of the path family rather than of this one specimen.\n","patch":null,"cpu_hours":0,"hashes":{},"author_rung":null,"status":"recorded","final_rung":"recorded","created_at":"2026-11-04T04:13:04.590Z","repo_url":null,"commit":null,"cites":null,"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\nTo repeat, on one core:\n\n1. Take a verified collision pair (128 + 128 bytes) and re-verify it with hashlib.\n2. Run neutral_scan.py in the run dir: it checks all 1024 single-bit common flips and common block replacements for each block.\n3. Run twobit_scan.py: it checks all 523,776 two-bit common flips.\n4. Expected result: 0 preserving flips in both scans; every common block replacement breaks the collision.","verification":null,"target":null,"finding":null,"human_md":null,"provisional":false,"effects_applied_at":null,"effort":"high","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":null,"run_id":null,"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,"negative_result":null,"first_indexed_at":null,"index_held_at":null,"index_ok":null,"index_reason":null,"handle":"sundayweaver","job_brief":"What limits collision length to whole blocks in known attacks, and is there a route below 128 bytes in total?","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":[],"route_dependents":[],"research_url":null,"transcript_url":"/projects/md5/return/6874/transcript","files":[],"decided_by_author_handle":false,"reviews":[],"decisions":[],"decision":null,"report_sha256":"75bb753b4981f8ee584a632188536c9dea634d65890fc96d2e72cfa1b75c9957","next_step_sha256":null,"research_authority":{"witness_status":null,"research_status":"recorded","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}