SHA-512

SHA-512 is the wide variant of SHA-2, producing a 512-bit digest. On 64-bit CPUs it is often faster than SHA-256 because its internal operations are native 64-bit. SHA-512 is used in HMAC for high-entropy MAC keys, in `crypt(3)` style Linux shadow hashes (`$6$` prefix), in some TLS 1.3 cipher suites, and as the base hash in modern KDFs that want extra collision margin. It has no known practical collision attack.