inthash

inthash is a versatile library for generating integer hash values in Javascript
and Typescript using Knuth's multiplicative method. With a user-friendly
interface, this library allows you to obfuscate predictable numbers, making it
ideal for scenarios like 'Auto Increment' values in databases. inthash supports
number, string, bigint.

Installation

Node.js

``bash
npm install inthash
`

Deno

`ts
import { Hasher } from "https://deno.land/x/inthash/mod.ts";
`

Usage

$3

Run the following command to generate random settings for your hasher:

`bash


Node.js:

npx inthash

Deno:

deno run jsr:@denostack/inthash/cli

Bun

bunx inthash

Output:

{

"bits": 53,

"prime": "6456111708547433",

"inverse": "3688000043513561",

"xor": "969402349590075"

}

`

$3

Create a hasher with the generated settings:

`ts
const hasher = new Hasher({
bits: 53, // Javascript, Number.MAX_SAFE_INTEGER
prime: "6456111708547433", // Random Prime
inverse: "3688000043513561", // Modular Inverse
xor: "969402349590075", // Random n-bit xor mask
});

const encoded = hasher.encode(100); // result: 6432533451586367
const decoded = hasher.decode(encoded); // result: 100
`

!diagram

`ts
// You can obfuscate predictable numbers like 'Auto Increment'!
hasher.encode(0); // 969402349590075
hasher.encode(1); // 6085136369434450
hasher.encode(2); // 4132187376469225
hasher.encode(3); // 2180123214014976

hasher.encode(Number.MAX_SAFE_INTEGER - 3); // 2024647471942759
hasher.encode(Number.MAX_SAFE_INTEGER - 2); // 6827076040726014
hasher.encode(Number.MAX_SAFE_INTEGER - 1); // 4875011878271765
hasher.encode(Number.MAX_SAFE_INTEGER); // 2922062885306540
`

inthash also supports string and bigint values:

`ts
// String input and output
const encoded = hasher.encode("100"); // "6432533451586367"
const decoded = hasher.decode(encoded); // "100"
`

`ts
// BigInt input and output
const encoded = hasher.encode(100n); // 6432533451586367n
const decoded = hasher.decode(encoded); // 100n
`

$3

To work with bigint(20) in MySQL, you need to handle 64-bit values. The old
version of IntHash supported up to 53-bit values
(Number.MAX_SAFE_INTEGER === 2**53 - 1). From v3 onwards, n-bit values are
supported:

`bash


Node.js:

npx inthash -b64

Deno:

deno run https://deno.land/x/inthash/cli.ts -b64

Output:

{

"bits": 64,

"prime": "16131139598801670337",

"inverse": "14287487925114175297",

"xor": "8502035541264656686"

}

``

See also

- optimus A PHP implementation of
Knuth's multiplicative hashing method. inthash is inspired by and ported from
this library.