88 lines
3.3 KiB
Handlebars
88 lines
3.3 KiB
Handlebars
# bigint-utils
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Some extra functions to work with modular arithmetics along with secure random numbers and probable prime (Miller-Rabin primality test) generation/testing using native JS (stage 3) implementation of BigInt. It can be used with Node.js (>=10.4.0) and [Web Browsers supporting BigInt](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt#Browser_compatibility).
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_The operations supported on BigInts are not constant time. BigInt can be therefore **[unsuitable for use in cryptography](https://www.chosenplaintext.ca/articles/beginners-guide-constant-time-cryptography.html)**_
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Many platforms provide native support for cryptography, such as [webcrypto](https://w3c.github.io/webcrypto/Overview.html) or [node crypto](https://nodejs.org/dist/latest/docs/api/crypto.html).
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## Installation
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bigint-utils is distributed as both an ES6 and a CJS module.
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The ES6 module is built for any [web browser supporting BigInt](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt#Browser_compatibility). The module only uses native javascript implementations and no polyfills had been applied.
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The CJS module is built as a standard node module.
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bigint-utils can be imported to your project with `npm`:
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```bash
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npm install bigint-utils
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```
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For web browsers, you can also [download the bundle from GitHub](https://raw.githubusercontent.com/juanelas/bigint-utils/master/dist/bigint-utils-latest.browser.mod.min.js).
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## Usage example
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With node js:
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```javascript
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const bigintUtils = require('bigint-utils');
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// Stage 3 BigInts with value 666 can be declared as BigInt('666')
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// or the shorter new no-so-linter-friendly syntax 666n
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let a = BigInt('5');
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let b = BigInt('2');
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let n = BigInt('19');
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console.log(bigintModArith.modPow(a, b, n)); // prints 6
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console.log(bigintModArith.modInv(BigInt('2'), BigInt('5'))); // prints 3
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console.log(bigintModArith.modInv(BigInt('3'), BigInt('5'))); // prints 2
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// Generation of a probable prime of 2048 bits
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const prime = await bigintUtils.prime(2048);
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// Testing if a prime is a probable prime (Miller-Rabin)
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if ( await bigintUtils.isProbablyPrime(prime) )
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// code if is prime
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// Get a cryptographically secure random number between 1 and 2**256 bits.
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const rnd = bigintUtils.randBetween(BigInt(2)**256);
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```
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From a browser, you can just load the module in a html page as:
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```html
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<script type="module">
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import * as bigintUtils from 'bigint-utils-latest.browser.mod.min.js';
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let a = BigInt('5');
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let b = BigInt('2');
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let n = BigInt('19');
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console.log(bigintModArith.modPow(a, b, n)); // prints 6
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console.log(bigintModArith.modInv(BigInt('2'), BigInt('5'))); // prints 3
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console.log(bigintModArith.modInv(BigInt('3'), BigInt('5'))); // prints 2
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(async function () {
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// Generation of a probable prime of 2018 bits
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const p = await bigintSecrets.prime(2048);
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// Testing if a prime is a probable prime (Miller-Rabin)
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const isPrime = await bigintSecrets.isProbablyPrime(p);
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alert(p.toString() + '\nIs prime?\n' + isPrime);
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// Get a cryptographically secure random number between 1 and 2**256 bits.
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const rnd = await bigintSecrets.randBetween(BigInt(2)**256);
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alert(rnd);
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})();
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</script>
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```
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# bigint-utils JS Doc
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{{>main}}
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* * *
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