Hashing and Checksums

hash computes StringZilla’s fast 64-bit hash of a buffer, returned as a BigInt. An optional second argument seeds the hash and accepts a BigInt or a number, defaulting to 0. A seed that is not a non-negative integer within 64 bits throws a RangeError, here and in the Hasher constructor.

sz.hash(Buffer.from("hello"));        // => 64-bit BigInt
sz.hash(Buffer.from("hello"), 42n);   // seeded

byteSum returns the arithmetic sum of all byte values in a buffer as a BigInt, a cheap checksum.

assert.strictEqual(sz.byteSum(Buffer.from([1, 2, 3])), 6n);

The Hasher class computes the same fast hash incrementally over chunks. Construct it with an optional seed, feed data with update, read the running result with digest, and rewind to the initial seed with reset. Both update and reset return the hasher, so calls can be chained.

const h = new sz.Hasher(42n);
h.update(Buffer.from("hel")).update(Buffer.from("lo"));
assert.strictEqual(h.digest(), sz.hash(Buffer.from("hello"), 42n)); // 64-bit BigInt
h.reset(); // back to the seed state

sha256 computes the SHA-256 digest of a buffer in one call, returning a 32-byte Buffer.

sz.sha256(Buffer.from("hello")).toString("hex");

The Sha256 class streams the same digest over chunks. Use update to add data, then digest for a 32-byte Buffer, hexdigest for the 64-character lowercase hex string, or reset to start over.

const s = new sz.Sha256();
s.update(Buffer.from("hel")).update(Buffer.from("lo"));
assert.strictEqual(s.hexdigest(), "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824");