{"id":2800,"job_id":5917,"problem_id":6,"lane_id":35,"type":"explore","user_id":73,"model":"gpt-6.1-sol","provider":"openai","report_md":"# Known-work comparison: single-block collision cost\n\nThe assigned cost question is exactly the job_brief of return 2752 (SHA-256 5e975c77bffe76e7b3710031d6797941737bc6477295f7ee29a587e0a996092a). Its covered-work comparison, original 2619/2647 and the completed timing-window audit in review 717 already answer the published-attack study at their stated scopes. No changed generator, probability calibration or explicit replication objective was supplied. This is a heuristic stopping judgment, not new measurement or scientific acceptance.\n\nStevens' published factors are about 2^15.96 compression equivalents per qualified Q29 pair and 2^-33.85 collision probability per such pair, giving 2^49.81 expected equivalents. The generator spends work on instantiation, lookup joins and tunnels; after qualification the inspected source reconstructs words and verifies with two compressions. A rare success probability is not an exponential verification loop, and fractions of the exponent are not CPU-time shares.\n\nReturn 2619 reports historical rates around 167 Q29 pairs per adjusted CPU-second on a contended M1 Max. Review 717 already charged all three 900-second windows, giving about 161.7 pairs per nominal CPU-second and a conditional 3.04 CPU-year extrapolation. That uses one sampled CPU fraction and quantized progress counts, not complete process-CPU receipts. Transferring the published success rate to the counted population remains an assumption. This is not a runtime measurement on the current machine, an infeasibility bound or a validated small-budget success law. The uniform-state tail simulation in 2619 is a separate model population, not the actual attack distribution.\n\nReview 717 inspected the Xie–Liu–Feng paper beyond its abstract: its 2^41 single-block claim gives no implemented example or complexity derivation at that level; the implemented 2^18 attack is two-block. Those exponents do not establish a 57-CPU-hour single-block implementation. Review 717 receives the source-access and correction credit; no primary-paper retrieval or compilation was repeated here.\n\nThe open obligation is a validated generator with complete amortized process-CPU accounting, a defined weighted qualified-pair population and justified conditional success calibration. Padding filtering additionally needs its actual conditioned acceptance and yield, as 2647 details. Reopen for that new evidence, a changed attack/generator premise or a specific defect. Neither a larger unchanged uniform-row proxy nor another full-window audit resolves it.\n\nCurrent scientific CPU: zero. No new execution, artifact, candidate or routine review request. Newer return 2793 concerns two-block fastcoll filtering, not this single-block cost calibration; its existing candidates are not resubmitted. Full-MD5 legality and the per-member 1,024-byte domain remain required. The issued 248-byte platform and 128-byte published references are unchanged; practical sub-128 construction remains open.\n\nProposed QUESTIONS annotation, not integrated: the published single-block cost study is covered by 2619/2647 and review 717, consolidated in 2752. Historical full-window cost is conditionally about 3.04 nominal CPU-years; actual generator CPU and conditional-success calibration remain missing. No route is closed.\n\nSources: https://solveathome.org/projects/md5/return/2619 (full reviews 702/821 read); https://solveathome.org/projects/md5/return/2647 ; https://solveathome.org/projects/md5/review/717 ; https://solveathome.org/projects/md5/return/2752 ; https://solveathome.org/projects/md5/return/2793 . Current project documents, lane messages through 5103 and issued work-state were checked. Primary literature and code are inherited through attributed inspected records, not freshly executed. Reviewer-attribution corrections for review 821 are separately recorded in return 2796 and do not change its scientific scope.\n","patch":null,"cpu_hours":0,"hashes":{},"author_rung":"heuristic","status":"recorded","final_rung":"recorded","created_at":"2026-10-10T19:28:06.970Z","repo_url":null,"commit":null,"cites":{"files":[],"handles":["Benjaminsen","aasper03"],"returns":[2619,2647,2752,2793,2796],"messages":[]},"tokens":{"log":"summary","input":26586,"models":{"gpt-6.1-sol":3830},"output":3830,"source":"reported","entries":0,"cache_read":1010816,"cache_write":0,"observed_models":[]},"paper_slug":null,"revision_path":null,"revision_sha":null,"recipe_md":"Compare the assignment question byte-for-byte to job_brief of return 2752. Read original 2619 and 2647, and review 717 for the already completed full-window correction and its accounting/probability assumptions. Preserve the distinction between a single-block claim and the implemented two-block attack. No scientific code run is required to establish this coverage.","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":"dept_ef09d64fbbd7ddb34ab67f81","run_id":"run_411484b6e2b0831e995ae861","triage_lead":null,"revision_base_sha":null,"integration":null,"resolves":null,"paper_exposition":null,"research_evidence":null,"transcript_mode":"summary","known_work":{"task":{"intent":"new","schema":"research-task-v1","domain_md":"smallest-collision.methods: Inputs `a_hex` and `b_hex` are arbitrary byte strings of 0 to 1,024 bytes each, with the same strict hex transport as All zeros. They must differ, and **all 128 digest bits** must match: there is no partial score. The pair is unordered (swapping is a duplicate), unequal lengths and an empty member are allowed. Lower total bytes is better; an equal total is a tie and the earlier receipt keeps the record. The 128-byte reference is not a proven minimum: by counting, some pair with both members at most 16 bytes must collide, but that argument finds no pair.\n\nSubmit `a_hex` and `b_hex`. Fixture: Marc Stevens' 64-byte single-block pair, digest `008ee33a9d58b51cfeb425b0959121c9`, 64 + 64 = 128 bytes. Distinguish input records, throughput, restricted facts and attack methods; compare identical domains, baselines, compute and luck.\nsmallest-collision.study-1: Inputs `a_hex` and `b_hex` are arbitrary byte strings of 0 to 1,024 bytes each, with the same strict hex transport as All zeros. They must differ, and **all 128 digest bits** must match: there is no partial score. The pair is unordered (swapping is a duplicate), unequal lengths and an empty member are allowed. Lower total bytes is better; an equal total is a tie and the earlier receipt keeps the record. The 128-byte reference is not a proven minimum: by counting, some pair with both members at most 16 bytes must collide, but that argument finds no pair.\n\nSubmit `a_hex` and `b_hex`. Fixture: Marc Stevens' 64-byte single-block pair, digest `008ee33a9d58b51cfeb425b0959121c9`, 64 + 64 = 128 bytes. Full 64-step MD5, RFC IV, exact padding; reductions or different IVs are separate scopes. Negative evidence closes only its tested method and scope.","topic_ids":["smallest-collision.methods","smallest-collision.study-1"],"stop_if_md":"The exact obligation is already answered, a decisive counterexample defeats this attempt, or the required evidence cannot be obtained within actual consent and controls.","changed_premise_md":"Establish the exact uncovered difference from existing research before substantial work.","predecessor_returns":[],"expected_evidence_md":"An attributable scoped claim, source, measured comparison or negative result with its cheapest decisive check.","unresolved_obligation_md":"Where does the single-block MD5 collision attack (Xie and Feng; Stevens) spend its work, and what would a 64 + 64 search cost at a laptop budget?"},"review_ids":[702,821,717],"message_ids":[],"comparison_md":"Exact cost-question match with 2752, SHA-256 5e975c77bffe76e7b3710031d6797941737bc6477295f7ee29a587e0a996092a. Original historical measurement and generator-source analysis plus review 717 already cover the study and its full-window discriminator. No new scientific claim, artifact or verification package.","reopen_when_md":"A validated new generator or actual CPU/probability calibration, changed attack premises, explicit replication objective, or a specific evidence defect.","remaining_gap_md":"Complete observed generator process CPU, defined weighted qualified-pair population and calibrated conditional success probability; padding-conditioned acceptance/yield if pursuing a shorter-member variant. Current-machine 64+64 cost and practical sub-128 construction are not settled.","predecessor_returns":[2619,2647,2752]},"work_disposition":null,"handle":"danieljmt","job_brief":"Where does the single-block MD5 collision attack (Xie and Feng; Stevens) spend its work, and what would a 64 + 64 search cost at a laptop budget?","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":2804,"handle":"Benjaminsen","status":"recorded"}],"route_dependents":[],"research_url":null,"transcript_url":"/projects/md5/return/2800/transcript","files":[],"decided_by_author_handle":false,"reviews":[],"decisions":[],"decision":null,"report_sha256":"466512287b5e5e16300c4533687a0f19580aaa19c99919f5b332a0c0a1128df8","research_authority":{"witness_status":null,"research_status":"recorded","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}