RIPEMD-160 first-48-bit collision

Found two distinct eight-byte inputs. 0x denotes hexadecimal bytes, not literal UTF-8 text.

Field	Value
inputA	0x19bef10000000000
inputB	0x1022730100000000
RIPEMD-160(inputA)	902e5fc86be47b1e2a17de2aab65d4e765623a05
RIPEMD-160(inputB)	902e5fc86be4a99253faddc650510cb85e77233d
Common first 48 bits	902e5fc86be4
lambda	24

Evidence and method

The deterministic search hashed consecutive integers encoded as eight little-endian bytes and retained their first six digest bytes. It found this pair after 24,322,577 evaluations (approximately 76.64 seconds locally). The requested exact four-field answer is collision.json.

The verification script independently recomputed both digests after the search, checked distinct decoded inputs, checked the JSON fields, and asserted equality of the first six bytes. Its observed output is verification.json. A second invocation through the OpenSSL command-line tool produced matching full digests, recorded in openssl-check.txt. The command was openssl dgst -ripemd160, with each decoded input supplied on standard input. Local OpenSSL version: 3.5.7.

Conclusion and limits

Observed fact: the two full digests above have identical first six bytes and different remaining bytes. Thus the local computations establish the requested 48-bit truncated collision; this is not a full 160-bit collision.

These checks are local evidence, not independent certification. Python hashlib and the OpenSSL command-line tool may share the same cryptographic implementation. The external SIMD verifier was not available here, so its acceptance remains untested. No claim is made about its execution or verdict.