171 lines
4.9 KiB
Markdown
171 lines
4.9 KiB
Markdown
# rsa-compat.js
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JavaScript RSA utils that work on Windows, Mac, and Linux with or without C compiler
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In order to provide a module that "just works" everywhere, we mix and match methods
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from `node.js` core, `ursa`, `forge`, and others.
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This is useful for **certbot** and **letsencrypt**.
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(in the future we'd like to provide the same API to the browser)
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Examples
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--------
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Generate an RSA Keypair:
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```javascript
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var RSA = require('rsa-compat').RSA;
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var bitlen = 1024;
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var exp = 65537;
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var options = { public: true, pem: true, internal: true };
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RSA.generateKeypair(bitlen, exp, options, function (err, keypair) {
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console.log(keypair);
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});
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```
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Here's what the object might look like:
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`console.log(keypair)`:
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```javascript
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{ publicKeyPem: '-----BEGIN RSA PUBLIC KEY-----\n/*base64 pem-encoded string*/'
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, privateKeyPem: '-----BEGIN RSA PRIVATE KEY-----\n/*base64 pem-encoded string*/'
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, privateKeyJwk: {
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kty: "RSA"
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, n: '/*base64 modulus n = pq*/'
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, e: '/*base64 exponent (usually 65537)*/'
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, d: '/*base64 private exponent (d = e^−1 (mod ϕ(n))/'
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, p: '/*base64 first prime*/'
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, q: '/*base64 second prime*/'
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, dp: '/*base64 first exponent for Chinese remainder theorem (dP = d (mod p−1))*/'
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, dq: '/*base64 Second exponent, used for CRT (dQ = d (mod q−1))/'
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, qi: '/*base64 Coefficient, used for CRT (qinv = q^−1 (mod p))*/'
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}
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, publicKeyJwk: {
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kty: "RSA"
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, n: '/*base64 modulus n = pq*/'
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, e: '/*base64 exponent (usually 65537)*/'
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}
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, _ursa: '/*undefined or intermediate ursa object*/'
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, _ursaPublic: '/*undefined or intermediate ursa object*/'
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, _forge: '/*undefined or intermediate forge object*/'
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, _forgePublic: '/*undefined or intermediate forge object*/'
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}
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```
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NOTE: this object is JSON safe as _ursa and _forge will be ignored
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See http://crypto.stackexchange.com/questions/6593/what-data-is-saved-in-rsa-private-key to learn a little more about the meaning of the specific fields in the JWK.
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API
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---
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* `RSA.generateKeypair(bitlen, exp, options, cb)`
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* `RSA.exportPrivatePem(keypair)`
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* `RSA.exportPublicPem(keypair)`
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* `RSA.exportPrivateJwk(keypair)`
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* `RSA.exportPublicJwk(keypair)`
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* `RSA.signJws(keypair, payload, nonce)`
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* `RSA.generateCsrPem(keypair, names)`
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* `RSA.generateCsrDerWeb64(keypair, names)`
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`keypair` can be any object with any of these keys `publicKeyPem, privateKeyPem, publicKeyJwk, privateKeyJwk`
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### RSA.generateKeypair(bitlen, exp, options, cb)
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Create a private keypair and export it as PEM, JWK, and/or internal formats
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```javascript
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RSA.generateKeypair(null, null, null, function (keypair) { /*...*/ });
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RSA.generateKeypair(1024, 65537, { pem: false, public: false, internal: false }, function (keypair) { /*...*/ });
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```
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`bitlen`: *1024* (default), 2048, or 4096
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`exp`: *65537* (default)
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`options`:
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```javascript
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{ public: false // export public keys
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, pem: false // export pems
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, jwk: true // export jwks
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, internal: false // preserve internal intermediate formats (_ursa, _forge)
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, thumbprint: false // JWK sha256 thumbprint
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, fingerprint: false // NOT IMPLEMENTED (RSA key fingerprint)
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}
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```
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### RSA.export*(keypair)
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You put in an object like `{ privateKeyPem: '...' }` or `{ publicKeyJwk: {} }`
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and you get back the keys in the format you requested.
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Note:
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* Private keys **can** be used to export both private and public keys
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* Public keys can **NOT** be used to generate private keys
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Example:
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```javascript
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var keypair = { privateKeyPem: '...' };
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keypair.publicKeyJwk = RSA.exportPublicJwk(keypair);
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console.log(keypair);
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```
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### RSA.signJws(keypair, payload, nonce)
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Generates a signature in JWS format (necessary for **certbot**/**letsencrypt**).
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```javascript
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var message = "Hello, World!"
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var nonce = crypto.randomBytes(16).toString('hex');
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var jws = RSA.signJws(keypair, message, nonce);
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console.log(jws);
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```
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The result looks like this:
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```javascript
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{ "header": {
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"alg": "RS256",
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"jwk": {
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"kty": "RSA",
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"n": "AMJubTfOtAarnJytLE8fhNsEI8wnpjRvBXGK/Kp0675J10ORzxyMLqzIZF3tcrUkKBrtdc79u4X0GocDUgukpfkY+2UPUS/GxehUYbYrJYWOLkoJWzxn7wfoo9X1JgvBMY6wHQnTKvnzZdkom2FMhGxkLaEUGDSfsNznTTZNBBg9",
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"e": "AQAB"
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}
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},
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"protected": "eyJub25jZSI6IjhlZjU2MjRmNWVjOWQzZWYifQ",
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"payload": "JLzF1NBNCV3kfbJ5sFaFyX94fJuL2H-IzaoBN-ciiHk",
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"signature": "Wb2al5SDyh5gjmkV79MK9m3sfNBBPjntSKor-34BBoGwr6n8qEnBmqB1Y4zbo-5rmvsoPmJsnRlP_hRiUY86zSAQyfbisTGrGBl0IQ7ditpkfYVm0rBWJ8WnYNqYNp8K3qcD7NW72tsy-XoWEjNlz4lWJeRdEG2Nt4CJgnREH4Y"
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}
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```
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### RSA.generateCsr*(keypair, names)
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You can generate the CSR in human-readable or binary / base64 formats:
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`RSA.generateCsrPem(keypair, names)`:
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```javascript
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var pem = RSA.generateCsrPem(keypair, [ 'example.com', 'www.example.com' ]);
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console.log(pem);
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```
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web-safe base64 for **certbot**/**letsencrypt**:
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`RSA.generateCsrDerWeb64(keypair, names)`:
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```javascript
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var web64 = RSA.generateCsrDerWeb64(keypair, [ 'example.com', 'www.example.com' ]);
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console.log(web64);
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```
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