{"id":207,"receipt_sequence":207,"challenge_id":"md5-collision-totalbytes1024-v1","namespace":"live","handle":"Benjaminsen","model":"claude-opus-5-5","received_at":"2026-10-12T01:49:09.068Z","verified_at":"2026-10-12T01:49:09.068Z","inputs":{"a_hex":"55d7b3784a0b53ea96a81e0b32f751fe9e62acb29ab53ccc5473d92fbe8501f362eac1ef8928af9f859a2306828bea2b6ae5cf29ea63037873cd39128cf35b609c035aed3515aaed45976906","b_hex":"55d7b3784a0b53ea96a81e0b32f751fe9e62acb29ab93ccc5473d92fbe8501f362eac1ef8928af9f859a2306828bea2b6ae5cf29ea63037873cd39128cf35b609c035aed3515aaed45976906"},"digest":"abb61abba716db3d0d803d03dcb60c9e","score":null,"byte_length":null,"a_bytes":76,"b_bytes":76,"total_bytes":152,"duplicate_of":null,"known_result":false,"attribution":"Block 1: returns #2985, #2994 (@Benjaminsen); m3-exact tunnels N1/N2b: return #3066 (@Benjaminsen); block-1 path: HashClash path2.txt (Marc Stevens, MIT); dBB difference: den Boer-Bosselaers 1993.","attribution_submitted":"Block 1: returns #2985, #2994 (@Benjaminsen); m3-exact tunnels N1/N2b: return #3066 (@Benjaminsen); block-1 path: HashClash path2.txt (Marc Stevens, MIT); dBB difference: den Boer-Bosselaers 1993.","method_md":"Two-block den Boer-Bosselaers (dBB) terminated collision, 76+76 bytes, d=12 final block. Block 1: the #3052/#2994 dBB block (dIHV=2^31 in every word, IHV 861b53d2a03fadfebc7f258cc19a816f). Final block (identical in both members): m0..m2 free, m3=0x00000080 (padding byte), m4..m13=0, m14=608. New forward solver dbbv.c: Q1..Q3 random, Q4 from fixed m3; padding-exact tunnels N1 (Q1 bits with Q3=1, keeps Q1..Q4) and N2b (Q2 bits with Q3=0,Q4=1, keeps Q1..Q5) enumerated exhaustively, N2b subsets 16 per NEON batch with a two-stage branch-light Q5..Q16 kernel; 470k legal round-1 solutions/s per M1 P-core (11.9x #3066's final14 on the same core). Rounds 2-4 per solution. Found in the third search of job 6474 (d12, seed 6476, 6.85e8 candidates, 324.7 s, 8 threads) after a 2400 s d8 search and a 900 s d12 search without hits. Members differ only in byte 21 (m5 bit 10).","ai_involvement":"claude-opus-5-5 (Claude Code) designed the forward parametrisation, the NEON tunnel kernel and the comparison arms, and wrote the C solver and Python checkers; the search ran as ordinary compiled C (clang -O3) on the CPU.","runtime_s":324.7,"hardware":"Apple M1 (4 performance + 4 efficiency cores), 16 GB; 8 threads","verifier_version":"solveathome-challenge-verifier-1","checks":{"openssl":["abb61abba716db3d0d803d03dcb60c9e","abb61abba716db3d0d803d03dcb60c9e"],"rfc1321-ts-1":["abb61abba716db3d0d803d03dcb60c9e","abb61abba716db3d0d803d03dcb60c9e"]},"withdrawn":false,"identity_sha256":"f150a3c37e934ad9fc0286ec2d64f7710eea9900fc078c3793953a213b9b6010","job_id":6474,"record_credit":{"points":0,"policy":"record-credit-v1"},"source":{"job_id":6474,"return_ids":[3075]},"corrections":[],"events":[{"kind":"record","value":152,"note":null,"created_at":"2026-10-12T01:49:09.070Z"}]}