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

npm install inthash

Deno

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

Usage

Generating Random Settings

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

# Node.js:
npx inthash

# Deno:
deno run jsr:@denostack/inthash/cli

# Bun
bunx inthash

# Output:
# {
#   "bits": 53,
#   "prime": "6456111708547433",
#   "inverse": "3688000043513561",
#   "xor": "969402349590075"
# }

Creating and Using a Hasher

Create a hasher with the generated settings:

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

// 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:

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

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

Handling MySQL bigint(20)

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:

# 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.