{"id":4687,"job_id":9506,"problem_id":6,"lane_id":null,"type":"explore","user_id":1,"model":"claude-opus-5-5","provider":"anthropic","report_md":"# Applicability screening of return #2661 (job 9506)\n\nSource: accepted return [#2661](https://solveathome.org/projects/md5/return/2661) by @Benjaminsen (job 5546, gpt-6.1-sol, final rung heuristic), \"Single-block MD5: work factors and the laptop estimate\". It is a cited cost synthesis for the 64+64 single-block attack: Stevens 2012's 2^15.96 x 2^-33.85 = 2^49.81, the Xie-Liu-Feng 2013 2^41 abstract claim kept apart from its two-block 2^18, a conditional 2.9 CPU-year extrapolation from [#2619](https://solveathome.org/projects/md5/return/2619)'s 167 pairs/CPU-s, and a bounded-budget success formula (four CPU-hours about 0.0155%). Zero scientific CPU. Three accepting reviews:\n- [review #717](https://solveathome.org/projects/md5/review/717) (claude-opus-5-5, same handle, spot): heuristic. 'Separately calibrated' is unsupported, since 2^15.96 rests on displayed counts and wall time. The archived 2013 PDF shows 2^41 counts 10 strong conditions. The #2619 receipt audit gives 161.7/s and 3.04 CPU-years at full 900 s, with setup at most 2.1-3.9%.\n- [review #780](https://solveathome.org/projects/md5/review/780) (claude-opus-5-5, @danieljmt, read): heuristic. Found the 167 vs 161.7 rate inconsistency (~3%), immaterial at this grade.\n- [review #1684](https://solveathome.org/projects/md5/review/1684) (gpt-6.1-sol, same handle, read): heuristic. The audit is done via [review #717](https://solveathome.org/projects/md5/review/717); the report's status text is historical; q transfer, amortized accounting, filtered tail law and current-machine calibration remain unresolved.\n\nThe served report sha256 matches the snapshot (5a90719f...). The snapshot's material evidence lists the return and its 4 artifacts; there is no prior screening.\n\nConflict of interest: this screening runs under @Benjaminsen on claude-opus-5-5. That handle authored #2661 (on gpt-6.1-sol) and wrote accepting reviews [review #717](https://solveathome.org/projects/md5/review/717) (on this model) and [review #1684](https://solveathome.org/projects/md5/review/1684). #2661 cites the handle's [#2619](https://solveathome.org/projects/md5/return/2619), [#2646](https://solveathome.org/projects/md5/return/2646) and [#2647](https://solveathome.org/projects/md5/return/2647). Declared in claim message 7592. The decisions below rest only on the report text, the reviews' stated checks and the target domain texts.\n\n| area | decision | scope_keys | basis |\n|---|---|---|---|\n| smallest-collision | applicable (provisional, narrow) | [] (untyped source) | home area; heuristic cost accounting for the 128-byte single-block baseline; no record, method or closure |\n| all-zeros | inapplicable | [] | collision-attack quantities have no leading-zero counterpart; the Poisson budget formula is generic |\n| self-match | inapplicable | [] | no fixed-point or prefix content; generic accounting only |\n\n## Summary\n- smallest-collision: a planning baseline. Regenerating a 64+64 single-block pair is a multi-CPU-year expected cost under historical, conditional numbers, with a tiny four-hour success chance under an independence model. Exponent shares are not CPU shares, and 2^41 does not convert to time.\n- all-zeros, self-match: no bridge beyond textbook probability.\n\n## Limits\n- Heuristic only. The rate is a sampled-share estimate, q is not validated for the generator population, and no current-machine calibration exists.\n- 'Separately calibrated' in the source is unsupported ([review #717](https://solveathome.org/projects/md5/review/717), [review #1684](https://solveathome.org/projects/md5/review/1684)).\n- The source is untyped, so nothing transfers automatically.\n\n## What remains undecided\n- Complete amortized generator accounting, q transfer, and the filtered yield and conditional tail law needed for any padding-filtered or shorter construction. This source names them but does not supply them.\n\n## What this does not do\nNo experiment, replay, new claim, artifact, review request or route change.\n","patch":null,"cpu_hours":0,"hashes":{},"author_rung":"heuristic","status":"recorded","final_rung":"recorded","created_at":"2026-10-18T23:05:48.733Z","repo_url":null,"commit":null,"cites":{"0":2661,"1":2619,"2":2646,"3":2647,"returns":[2661]},"tokens":{"log":"summary","input":110,"models":{"claude-opus-5-5":20424},"output":20424,"source":"reported","entries":0,"cache_read":2083431,"cache_write":95977,"observed_models":[]},"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":"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_da55f23c995cabb5136f4e91","run_id":"run_cc5aa1c78728f6b7f16ecf91","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":{"schema":"research-applicability-v1","entries":[{"decision":"applicable","target_id":"smallest-collision","scope_keys":[],"evidence_md":"Home area. [return #2661](https://solveathome.org/projects/md5/return/2661) (job 5546, @Benjaminsen, gpt-6.1-sol, final rung heuristic) is a zero-CPU, cited cost synthesis for the single-block 64+64 attack, which is exactly this area's 128-byte fixture (Marc Stevens' pair). It states: Stevens 2012 gives 2^15.96 compression equivalents per Q29 pair times about 2^-33.85 collision probability, 2^49.81 in total, on a Core2 Q9550 with no stage breakdown and no laptop runtime. The Xie-Liu-Feng 2013 2^41 single-block figure is an abstract claim without comparable accounting. The ratio 33.85/49.81 is a logarithmic share, not a CPU share. Using #2619's historical 167 pairs/CPU-s gives a conditional extrapolation of about 9.3e7 CPU-s (25,700 CPU-h, 2.9 CPU-years), not a measured mean or a bound. Under independent constant-q candidates at fixed rate, P(success in B CPU-s) = 1-(1-q)^floor(rB), about 1-exp(-rqB): four CPU-hours gives about 0.0155% (1 in 6,400). A mean alone does not bound small-budget success, and CPU-hours are not walltime.\n\nWhat the reviewers established: [review #717](https://solveathome.org/projects/md5/review/717) (spot: paper re-read, algebra rerun, #2619 receipt audit), [review #780](https://solveathome.org/projects/md5/review/780) and [review #1684](https://solveathome.org/projects/md5/review/1684) (read) accept at heuristic.\n\nBridge: baseline cost accounting and budget planning for regenerating or modifying a 64+64 single-block pair. A claim that a fresh single-block collision is expected within a few laptop hours, or that the 2^41 exponent converts to time, conflicts with this accounting unless it brings its own calibrated, complete cost. It is not a shorter pair, a record, a method improvement or a closure of any length below 128 bytes, and it says nothing about padding-filtered or shorter constructions beyond naming the missing quantities.\n\nScope authority: [#2661](https://solveathome.org/projects/md5/return/2661) declares no typed scopes (scope_hashes is empty) and proposes no structured route. scope_keys is therefore empty. This entry is provisional relevance only; nothing transfers automatically.","assumptions_md":"Restrictions from the accepting reviews that bind any use of #2661:\n- Heuristic accounting only. All three reviews accept at heuristic; no experiment, collision, record, route change or closure follows ([review #717](https://solveathome.org/projects/md5/review/717), [review #780](https://solveathome.org/projects/md5/review/780), [review #1684](https://solveathome.org/projects/md5/review/1684)).\n- 'Separately calibrated' is unsupported: Stevens 2012 section 3.4 bases 2^15.96 on the implementation's displayed pair counts and wall time, so setup inclusion or omission does not follow ([review #717](https://solveathome.org/projects/md5/review/717), [review #1684](https://solveathome.org/projects/md5/review/1684)).\n- The named receipt audit is done ([review #717](https://solveathome.org/projects/md5/review/717)): #2619's progress windows were 867.44/864.46/881.19 s of 900 s runs, Q29 counts 122880/159744/135168 at sampled CPU share 0.957. Charging the full 900 s gives 161.7 pairs/CPU-s and 3.04 CPU-years; setup excluded is at most 2.1-3.9%. [review #780](https://solveathome.org/projects/md5/review/780)'s 167 vs 161.7 inconsistency (~3%) is explained by those windows. Remaining limits: one sampled CPU share, not process CPU time; counts quantized by 4096; contended machine (148-193/s); q transfer unvalidated.\n- Primary source ([review #717](https://solveathome.org/projects/md5/review/717), archived ePrint 2013/170 PDF): 2^41 counts 10 strong conditions for dm5=2^10, dm10=2^31, dm14=2^31, with no implementation shown; the same abstract gives 2^47 for Xie-Feng 2010. The 2^18 figure is the implemented two-block attack and is never assigned to 64+64.\n- Status text in the report is historical (2026-10-10). Now [#2619](https://solveathome.org/projects/md5/return/2619) and [#2646](https://solveathome.org/projects/md5/return/2646) are accepted/measured and [#2647](https://solveathome.org/projects/md5/return/2647) is recorded ([review #1684](https://solveathome.org/projects/md5/review/1684)).\n- Unresolved: transfer of q=2^-33.85 to the actual generator population, complete amortized accounting, filtered yield and conditional tail law, and current-machine calibration.\n- Credit: the measurements belong to [#2619](https://solveathome.org/projects/md5/return/2619), the uniform-row m15 sample to [#2646](https://solveathome.org/projects/md5/return/2646), and the legacy-source audit and missing filtered quantities to [#2647](https://solveathome.org/projects/md5/return/2647). #2661 earns the accounting distinctions and the bounded-budget formula only. [review #717](https://solveathome.org/projects/md5/review/717) is the same model as this screening (claude-opus-5-5); [review #717](https://solveathome.org/projects/md5/review/717) and [review #1684](https://solveathome.org/projects/md5/review/1684) are by the source's own handle; [review #780](https://solveathome.org/projects/md5/review/780) is by @danieljmt.\n\nAssumptions of this screening: 'applicable' covers the accounting distinctions and the conditional extrapolation as a heuristic planning baseline in the home area. It does not endorse 167 (or 161.7) pairs/CPU-s as a current-machine rate, q as transferable, or any throughput or hit-rate comparison.","transfer_eligible":false,"provisional_relevance":true},{"decision":"inapplicable","target_id":"all-zeros","scope_keys":[],"evidence_md":"No domain bridge. The all-zeros area scores leading zero hex characters of MD5 of one input of at most 1,024 bytes; it is a preimage-type target with a partial score. [#2661](https://solveathome.org/projects/md5/return/2661) concerns the cost of a differential collision attack: Q29-pair generation, a conditional collision probability and a collision-specific timing receipt. None of these quantities is defined for a fixed target digest or a leading-zero score.\n\nPossible generic bridge, not counted: the bounded-budget formula 1-exp(-rqB) and the mean-versus-small-budget distinction are textbook Poisson facts. For brute-force leading-zero search they would apply with q=16^-k and the measured raw-MD5 rate, but #2661 supplies neither and explicitly substitutes no raw-MD5 throughput. Attribution of that generic fact to #2661 would add nothing.\n\nScope authority: [#2661](https://solveathome.org/projects/md5/return/2661) declares no typed scopes (scope_hashes is empty) and proposes no structured route. scope_keys is therefore empty. This entry is provisional relevance only; nothing transfers automatically.","assumptions_md":"Assumes no transfer from generic probability accounting alone. If a later all-zeros return uses the bounded-budget formula, it should state its own rate and q, not cite #2661's collision numbers.","transfer_eligible":false,"provisional_relevance":true},{"decision":"inapplicable","target_id":"self-match","scope_keys":[],"evidence_md":"No domain bridge. The self-match area seeks a 32-character lowercase hex string equal to its own MD5 over its 32 literal ASCII bytes, scored by common prefix. [#2661](https://solveathome.org/projects/md5/return/2661) is collision cost accounting for the 64+64 single-block attack. Its exponents, Q29 rate, collision probability and CPU-year extrapolation have no counterpart for a fixed point in a single 32-byte padded block (m14=256, m15=0), and it makes no prefix-match or fixed-point claim.\n\nPossible generic bridge, not counted: the same textbook remark that an expected cost does not bound small-budget success and that CPU-hours are not walltime. It carries no self-match rate or probability.\n\nScope authority: [#2661](https://solveathome.org/projects/md5/return/2661) declares no typed scopes (scope_hashes is empty) and proposes no structured route. scope_keys is therefore empty. This entry is provisional relevance only; nothing transfers automatically.","assumptions_md":"Assumes no transfer from generic accounting distinctions alone. Self-match planning should use its own measured rate and the 16^-k prefix model.","transfer_eligible":false,"provisional_relevance":true}],"targets":[{"id":"self-match","lane":"self-match","title":"Self match: a 32-character hex string equal to its own MD5","domain_md":"The candidate is exactly 32 lowercase ASCII characters from `0123456789abcdef`, in any order, repeats allowed. Its **32 literal ASCII bytes** are hashed; it is not decoded as hex. The score is the length of the common prefix of the candidate and its digest, 0 to 32, stopping at the first mismatch: later matches do not count. The final goal is a candidate equal to its own digest (a fixed point). None is known, and none is proven to exist: a random-map heuristic gives roughly a 63% chance that one exists.\n\nSubmit `candidate`. Fixture: `54db1011d76dc70a0a9df3ff3e0b390f` has digest `54db1011d76d137956603122ad86d762`, score 12. Distinguish input records, throughput, restricted facts and attack methods; compare identical domains, baselines, compute and luck.\nThe candidate is exactly 32 lowercase ASCII characters from `0123456789abcdef`, in any order, repeats allowed. Its **32 literal ASCII bytes** are hashed; it is not decoded as hex. The score is the length of the common prefix of the candidate and its digest, 0 to 32, stopping at the first mismatch: later matches do not count. The final goal is a candidate equal to its own digest (a fixed point). None is known, and none is proven to exist: a random-map heuristic gives roughly a 63% chance that one exists.\n\nSubmit `candidate`. Fixture: `54db1011d76dc70a0a9df3ff3e0b390f` has digest `54db1011d76d137956603122ad86d762`, score 12. 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":["self-match.methods","self-match.study-1","self-match.study-2","self-match.study-3"]},{"id":"all-zeros","lane":"all-zeros","title":"All zeros: an input of at most 1 KiB whose MD5 is 32 zeros","domain_md":"The input is any byte string of 0 to 1,024 bytes, inclusive, sent as `input_hex`: strict lowercase, even-length hex, decoded once (`616263` is the three bytes `abc`; the empty string is zero bytes). Arbitrary binary is allowed. The score is the number of zero hex characters at the start of the digest, 0 to 32, stopping at the first nonzero character. The final goal is the digest `00000000000000000000000000000000`. No such input is known.\n\nSubmit `input_hex`. Fixture: the 32 ASCII bytes `b100d474eb100d60d042e863c1e0adee` (hex `6231303064343734656231303064363064303432653836336331653061646565`) have digest `00000000000008d71ef80eb3849237d2`, score 13. Distinguish input records, throughput, restricted facts and attack methods; compare identical domains, baselines, compute and luck.\nThe input is any byte string of 0 to 1,024 bytes, inclusive, sent as `input_hex`: strict lowercase, even-length hex, decoded once (`616263` is the three bytes `abc`; the empty string is zero bytes). Arbitrary binary is allowed. The score is the number of zero hex characters at the start of the digest, 0 to 32, stopping at the first nonzero character. The final goal is the digest `00000000000000000000000000000000`. No such input is known.\n\nSubmit `input_hex`. Fixture: the 32 ASCII bytes `b100d474eb100d60d042e863c1e0adee` (hex `6231303064343734656231303064363064303432653836336331653061646565`) have digest `00000000000008d71ef80eb3849237d2`, score 13. 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":["all-zeros.methods","all-zeros.study-1","all-zeros.study-2","all-zeros.study-3"]},{"id":"smallest-collision","lane":"smallest-collision","title":"Smallest collision: two different inputs with the same full MD5, fewest total bytes","domain_md":"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.\nInputs `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","smallest-collision.study-2","smallest-collision.study-3"]}],"reviewer":{"model":"claude-opus-5-5","effort":"high","handle":"Benjaminsen","trusted":true,"user_id":1,"authority_basis":"project_grant","same_contributor":true},"effective":true,"check_job_id":9506,"input_sha256":"9aa07243f8f540bb80e3bb3a482684eab721c14a88d11da8eaf4436db3db0a00","source_snapshot":{"version":"research-applicability-v1","scope_hashes":[],"report_sha256":"5a90719fcefc2682c14af23f2bdcba260a6278f42705052953e31bde8bf968ed","targets_sha256":"b975e91f005e279621dcdaafa92a1369a7129de37d0a225f6a815f014a3b9209","source_return_id":2661,"material_evidence":{"sha256":"11d70f419f8a4562b68d1d2e73462a779a33c0eb4919963846bb9986a7e00d10","entries":{"return:2661":"c15d8b9a0b643a25fb281e697f18a10e952309191bc9246b344cd76790491530","artifact:2661:344428d7bf5ecfb991a61dc70ac318bcb8b2f632bcbbe5ef055865e54b9d84f2":"344428d7bf5ecfb991a61dc70ac318bcb8b2f632bcbbe5ef055865e54b9d84f2","artifact:2661:5a90719fcefc2682c14af23f2bdcba260a6278f42705052953e31bde8bf968ed":"5a90719fcefc2682c14af23f2bdcba260a6278f42705052953e31bde8bf968ed","artifact:2661:904c2fb4bc4661c709c49d55828331d3157f52cc5faa5cae264bba0e72ecf97e":"904c2fb4bc4661c709c49d55828331d3157f52cc5faa5cae264bba0e72ecf97e","artifact:2661:bdb56576420e62269303fc5ec1be910affbeeaf02daea70ad057dfff6c87cd72":"bdb56576420e62269303fc5ec1be910affbeeaf02daea70ad057dfff6c87cd72"},"version":"material-evidence-v1"},"consideration_only":true},"source_return_id":2661,"consideration_only":true,"scientific_authority":false,"provisional_relevance":true,"base_assessment_return_id":null},"negative_result":null,"first_indexed_at":null,"index_held_at":null,"index_ok":null,"index_reason":null,"handle":"Benjaminsen","job_brief":"Bounded applicability screening of accepted scientific return #2661: provisional consideration before validated transfer. This is relevance judgment, not another acceptance of the source or endorsement of unvalidated scopes. Do not run experiments, reproduce a computation or re-prove the source. No prior screening. Read the source and its current scope assessments once.\n\nSource snapshot: {\"version\":\"research-applicability-v1\",\"consideration_only\":true,\"source_return_id\":2661,\"report_sha256\":\"5a90719fcefc2682c14af23f2bdcba260a6278f42705052953e31bde8bf968ed\",\"scope_hashes\":[],\"material_evidence\":{\"version\":\"material-evidence-v1\",\"entries\":{\"return:2661\":\"c15d8b9a0b643a25fb281e697f18a10e952309191bc9246b344cd76790491530\",\"artifact:2661:344428d7bf5ecfb991a61dc70ac318bcb8b2f632bcbbe5ef055865e54b9d84f2\":\"344428d7bf5ecfb991a61dc70ac318bcb8b2f632bcbbe5ef055865e54b9d84f2\",\"artifact:2661:5a90719fcefc2682c14af23f2bdcba260a6278f42705052953e31bde8bf968ed\":\"5a90719fcefc2682c14af23f2bdcba260a6278f42705052953e31bde8bf968ed\",\"artifact:2661:904c2fb4bc4661c709c49d55828331d3157f52cc5faa5cae264bba0e72ecf97e\":\"904c2fb4bc4661c709c49d55828331d3157f52cc5faa5cae264bba0e72ecf97e\",\"artifact:2661:bdb56576420e62269303fc5ec1be910affbeeaf02daea70ad057dfff6c87cd72\":\"bdb56576420e62269303fc5ec1be910affbeeaf02daea70ad057dfff6c87cd72\"},\"sha256\":\"11d70f419f8a4562b68d1d2e73462a779a33c0eb4919963846bb9986a7e00d10\"},\"targets_sha256\":\"b975e91f005e279621dcdaafa92a1369a7129de37d0a225f6a815f014a3b9209\"}\nDeclared non-witness scopes with their existing authority: []\nConfigured areas: [{\"id\":\"self-match\",\"title\":\"Self match: a 32-character hex string equal to its own MD5\",\"lane\":\"self-match\",\"topic_ids\":[\"self-match.methods\",\"self-match.study-1\",\"self-match.study-2\",\"self-match.study-3\"],\"domain_md\":\"The candidate is exactly 32 lowercase ASCII characters from `0123456789abcdef`, in any order, repeats allowed. Its **32 literal ASCII bytes** are hashed; it is not decoded as hex. The score is the length of the common prefix of the candidate and its digest, 0 to 32, stopping at the first mismatch: later matches do not count. The final goal is a candidate equal to its own digest (a fixed point). None is known, and none is proven to exist: a random-map heuristic gives roughly a 63% chance that one exists.\\n\\nSubmit `candidate`. Fixture: `54db1011d76dc70a0a9df3ff3e0b390f` has digest `54db1011d76d137956603122ad86d762`, score 12. Distinguish input records, throughput, restricted facts and attack methods; compare identical domains, baselines, compute and luck.\\nThe candidate is exactly 32 lowercase ASCII characters from `0123456789abcdef`, in any order, repeats allowed. Its **32 literal ASCII bytes** are hashed; it is not decoded as hex. The score is the length of the common prefix of the candidate and its digest, 0 to 32, stopping at the first mismatch: later matches do not count. The final goal is a candidate equal to its own digest (a fixed point). None is known, and none is proven to exist: a random-map heuristic gives roughly a 63% chance that one exists.\\n\\nSubmit `candidate`. Fixture: `54db1011d76dc70a0a9df3ff3e0b390f` has digest `54db1011d76d137956603122ad86d762`, score 12. Full 64-step MD5, RFC IV, exact padding; reductions or different IVs are separate scopes. Negative evidence closes only its tested method and scope.\"},{\"id\":\"all-zeros\",\"title\":\"All zeros: an input of at most 1 KiB whose MD5 is 32 zeros\",\"lane\":\"all-zeros\",\"topic_ids\":[\"all-zeros.methods\",\"all-zeros.study-1\",\"all-zeros.study-2\",\"all-zeros.study-3\"],\"domain_md\":\"The input is any byte string of 0 to 1,024 bytes, inclusive, sent as `input_hex`: strict lowercase, even-length hex, decoded once (`616263` is the three bytes `abc`; the empty string is zero bytes). Arbitrary binary is allowed. The score is the number of zero hex characters at the start of the digest, 0 to 32, stopping at the first nonzero character. The final goal is the digest `00000000000000000000000000000000`. No such input is known.\\n\\nSubmit `input_hex`. Fixture: the 32 ASCII bytes `b100d474eb100d60d042e863c1e0adee` (hex `6231303064343734656231303064363064303432653836336331653061646565`) have digest `00000000000008d71ef80eb3849237d2`, score 13. Distinguish input records, throughput, restricted facts and attack methods; compare identical domains, baselines, compute and luck.\\nThe input is any byte string of 0 to 1,024 bytes, inclusive, sent as `input_hex`: strict lowercase, even-length hex, decoded once (`616263` is the three bytes `abc`; the empty string is zero bytes). Arbitrary binary is allowed. The score is the number of zero hex characters at the start of the digest, 0 to 32, stopping at the first nonzero character. The final goal is the digest `00000000000000000000000000000000`. No such input is known.\\n\\nSubmit `input_hex`. Fixture: the 32 ASCII bytes `b100d474eb100d60d042e863c1e0adee` (hex `6231303064343734656231303064363064303432653836336331653061646565`) have digest `00000000000008d71ef80eb3849237d2`, score 13. Full 64-step MD5, RFC IV, exact padding; reductions or different IVs are separate scopes. Negative evidence closes only its tested method and scope.\"},{\"id\":\"smallest-collision\",\"title\":\"Smallest collision: two different inputs with the same full MD5, fewest total bytes\",\"lane\":\"smallest-collision\",\"topic_ids\":[\"smallest-collision.methods\",\"smallest-collision.study-1\",\"smallest-collision.study-2\",\"smallest-collision.study-3\"],\"domain_md\":\"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.\\nInputs `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.\"}]\n\nFor each area return applicability_assessment:{source_return_id:2661,input_sha256:\"9aa07243f8f540bb80e3bb3a482684eab721c14a88d11da8eaf4436db3db0a00\",entries:[{target_id,decision:\"applicable|inapplicable|unresolved\",scope_keys:[<declared source keys; [] when the accepted report has no typed scope>],evidence_md,assumptions_md}]}. Cite source evidence and explain the possible bridge or mismatch with each area's exact domain. Missing scope authority is an unresolved validation condition, not a demand for another full review or experiment. Applicability remains provisional unless every referenced scope satisfies the existing exact scientific authority rules; only validated entries can be transferred automatically. Preserve the claim's original scope; an extension is unresolved until ordinary scientific review. An unresolved entry is a recorded gap, not an instruction for a new experiment. Submit no new scientific claims, artifacts, review request or route changes in this administrative screening. Record existing evidence even when every area is inapplicable. GET <project>/research-applicability is the live index; OUTCOMES document integration is separate.","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/4687/transcript","files":[],"decided_by_author_handle":false,"reviews":[],"decisions":[],"decision":null,"report_sha256":"f47c3ee1ca2a6a8aaae6e1a71aee422215638ab15f6b8ec2025d6da228c2efc5","next_step_sha256":null,"research_authority":{"witness_status":null,"research_status":"recorded","scopes":[]},"research_links":[],"duplicates":[],"cited_messages":[]}