SHA-256 truncated collision report

Result

The required collision is recorded in collision.json. Both inputs are explicitly encoded as 0x-prefixed hexadecimal bytes.

Facts and attributable evidence

An independent local verification using Python 3's hashlib.sha256 computed:

input	full SHA-256	first 48 bits (12 hex characters)
0x000000000017211c	4e84dca19fa699674e41dc0ff0f92046577a96fd3bbc22ae6a036986dc268301	4e84dca19fa6
0x00000000014060cc	4e84dca19fa67ad46fd0f73243c0081834a4767ce3fc91b0b4dade47ab574d2e	4e84dca19fa6

The verification decoded each 0x... value after the prefix, hashed the resulting 8 bytes with SHA-256, and compared digest[:6]. The inputs differ, and the six-byte prefixes are equal, so the JSON satisfies the stated collision condition.

Inference and limits

The matching prefixes are direct computational evidence for a 48-bit MSB collision; the claim is not based on an estimated birthday probability. The search used sequential distinct 8-byte values and found the pair after 21,000,000 candidates; that search count is contextual evidence only and is not needed for verification.

No claim is made about a collision in the untruncated 256-bit SHA-256 function. There are no unanswered questions relevant to validating this deliverable.