keypair is a a RSA PEM key generator written in javascript. keypair implements a lot of cryptographic primitives on its own or by borrowing from other libraries where possible, including node-forge. An issue was discovered where this library was generating identical RSA keys used in SSH. This would mean that the library is generating identical P, Q (and thus N) values which, in practical terms, is impossible with RSA-2048 keys. Generating identical values, repeatedly, usually indicates an issue with poor random number generation, or, poor handling of CSPRNG output. Issue 1: Poor random number generation (`GHSL-2021-1012`). The library does not rely entirely on a platform provided CSPRNG, rather, it uses it's own counter-based CMAC approach. Where things go wrong is seeding the CMAC implementation with "true" random data in the function `defaultSeedFile`. In order to seed the AES-CMAC generator, the library will take two different approaches depending on the JavaScript execution environment. In a browser, the library will use [`window.crypto.getRandomValues()`](https://github.com/juliangruber/keypair/blob/87c62f255baa12c1ec4f98a91600f82af80be6db/index.js#L971). However, in a nodeJS execution environment, the `window` object is not defined, so it goes down a much less secure solution, also of which has a bug in it. It does look like the library tries to use node's CSPRNG when possible unfortunately, it looks like the `crypto` object is null because a variable was declared with…

Affected: npm: keypair

## Description and Impact

A bug in the pseudo-random number generator used by [keypair](https://github.com/juliangruber/keypair) versions up to and including 1.0.3 could allow for weak RSA key generation. This could enable an attacker to decrypt confidential messages or gain authorized access to an account belonging to the victim. We recommend replacing any RSA keys that were generated using keypair version 1.0.3 or earlier.

## Fix

* The [bug](https://github.com/juliangruber/keypair/blob/87c62f255baa12c1ec4f98a91600f82af80be6db/index.js#L1008) in the pseudo-random number generator is fixed in commit [`9596418`](https://github.com/juliangruber/keypair/commit/9596418d3363d3e757676c0b6a8f2d35a9d1cb18). * If the crypto module is available, it is used instead of the pseudo-random number generator. Also fixed in [`9596418`](https://github.com/juliangruber/keypair/commit/9596418d3363d3e757676c0b6a8f2d35a9d1cb18)

## Additional Details

The specific [line](https://github.com/juliangruber/keypair/blob/87c62f255baa12c1ec4f98a91600f82af80be6db/index.js#L1008) with the flaw is:

```javascript b.putByte(String.fromCharCode(next & 0xFF)) ```

The [definition](https://github.com/juliangruber/keypair/blob/87c62f255baa12c1ec4f98a91600f82af80be6db/index.js#L350-L352) of `putByte` is

```javascript util.ByteBuffer.prototype.putByte = function(b) { this.data += String.fromCharCode(b); }; ```

Simplified, this is `String.fromCharCode(String.fromCharCode(next & 0xFF))`. This results in most…