# rsa-compat.js

JavaScript RSA utils that work on Windows, Mac, and Linux with or without C compiler

In order to provide a module that "just works" everywhere, we mix and match methods
from `node.js` core, `ursa`, `forge`, and others.

(in the future we'd like to provide the same API to the browser)

Examples
--------

Generate an RSA Keypair:

```javascript
var PromiseA = require('bluebird');
var RSA = PromiseA.promisify(require('rsa-compat').RSA);

var bitlen = 1024;
var exp = 65537;
var options = { public: true, pem: true, internal: true };

RSA.generateKeypair(bitlen, exp, options).then(function (keypair) {
  console.log(keypair);
});
```

`console.log(keypair)`:
```javascript
// http://crypto.stackexchange.com/questions/6593/what-data-is-saved-in-rsa-private-key

{ publicKeyPem: '/*base64 pem-encoded string*/'
, privateKeyPem: '/*base64 pem-encoded string*/'
, privateKeyJwk: {
    kty: "RSA"
  , n: '/*base64 modulus n = pq*/'
  , e: '/*base64 exponent (usually 65537)*/'
  , d: '/*base64 private exponent (d = e^−1 (mod ϕ(n))/'
  , p: '/*base64 first prime*/'
  , q: /*base64 second prime*/
  , dp: /*base64 first exponent for Chinese remainder theorem (dP = d (mod p−1))*/
  , dq: /*base64 Second exponent, used for CRT (dQ = d (mod q−1))/
  , qi: /*base64 Coefficient, used for CRT (qinv = q^−1 (mod p))*/
  }
, publicKeyJwk: {
    kty: "RSA"
  , n: /*base64 modulus n = pq*/
  , e: /base64 exponent (usually 65537)*/
  }
, _ursa: /*undefined or intermediate ursa object*/
, _forge: /*undefined or intermediate forge object*/
}

// NOTE: this object is JSON safe as _ursa and _forge will be ignored
```


API
---

* `RSA.generateKeypair(bitlen, exp, options, cb)`
* `RSA.importPemPrivateKey(privatePem)`

### RSA.generateKeypair(bitlen, exp, options, cb)

Create a private keypair and export it as PEM, JWK, and/or internal formats

```javascript
RSA.generateKeypair(null, null, null, function (keypair) { /*...*/ });

RSA.generateKeypair(1024, 65537, { pem: false, public: false, internal: false }, function (keypair) { /*...*/ });
```

`bitlen`: *1024* (default), 2048, or 4096

`exp`: *65537* (default)

`options`:
```javascript
{ public: false       // export public keys
, pem: false          // export pems
, jwk: true           // export jwks
, internal: false     // preserve internal intermediate formats (_ursa, _forge)
, thumbprint: false   // JWK sha256 thumbprint
, fingerprint: false  // NOT IMPLEMENTED (RSA key fingerprint)
}
```

### RSA.import(keypair, options, cb)

Import a private key or public key as PEM, JWK, and/or internal formats

`rsa`:
```javascript
{ publicKeyPem: '...'
, privateKeyPem: '...'
, privateKeyJwk: { /*...*/ }
, publicKeyJwk: { /*...*/ }
, _ursa: '[Object object]'
, _forge: '[Object object]'
}
```

`options`:
```
// same as above, except the following are also added
{ private: true   // export private key
                  // (as opposed to using a private key
                  // solely to export the public key)
}
```

### Other

(the code is there, but they aren't exposed yet)

* `toStandardB64(certbuf.toString('base64'))`
* `thumbprint(publicPem)`
* `generateCsr(privateKeyPem, ['example.com'])`

```
    cert = toStandardB64(certbuf.toString('base64'))
    cert=cert.match(/.{1,64}/g).join('\n');
    return '-----BEGIN CERTIFICATE-----\n'+cert+'\n-----END CERTIFICATE-----';
```