How to create RSA key in Dart?

Question

I am trying to create an RSA key using Dart. The problem seems to be related to SecureRandom initiation. Unfortunately, the documentation is vague or does not exist. (He literally says that he uses a "File" or "URL", none of which work). Does anyone know how this should work?

Includes:

import 'package:cipher/cipher.dart';
import 'package:bignum/bignum.dart';

Relevant code (taken from an example that I found that should have worked):

var rsapars = new RSAKeyGeneratorParameters(new BigInteger("65537"), 4096, 12);
var params = new ParametersWithRandom(rsapars, new SecureRandom());

var keyGenerator = new KeyGenerator("RSA")
  ..init( params );

var keyPair = keyGenerator.generateKeyPair();

Answer 1

From some unit tests, I gathered some information on how this might work. Perhaps this will help you overcome this obstacle.

import 'package:cipher/cipher.dart';
import 'package:bignum/bignum.dart';
import "package:cipher/impl/base.dart";
import "package:cipher/random/secure_random_base.dart";

main() {
  initCipher();
  var rnd = new FixedSecureRandom();
  var rsapars = new RSAKeyGeneratorParameters(new BigInteger("65537"), 4096, 12);
  var params = new ParametersWithRandom(rsapars, rnd);

  var keyGenerator = new KeyGenerator("RSA")
    ..init( params );

  var keyPair = keyGenerator.generateKeyPair();
  print(keyPair);
}

class FixedSecureRandom extends SecureRandomBase {

  var _next = 0;
  var _values = [
    75,88,182,94,166,69,30,196,252,236,154,103,237,207,120,199,211,4,22,27,126,204,106,203,29,26,93,69,154,89,194,120,140,155,95,9,64,242,227,83,56,85,12,16,62,129,190,211,18,121,169,203,212,163,187,187,117,124,170,12,112,111,19,133,191,117,36,123,231,153,177,155,230,155,239,249,210,79,203,82,120,30,148,199,232,132,132,145,101,186,136,89,156,85,204,18,126,249,24,109,220,42,173,181,237,186,244,78,234,51,210,164,2,109,69,15,127,94,62,219,166,17,26,136,33,23,40,228,117,210,195,135,171,254,220,250,159,123,135,190,59,253,31,116,4,130,214,100,108,131,98,215,162,43,73,131,200,193,196,25,254,124,111,12,43,190,57,235,182,46,245,103,14,156,248,6,118,46,90,156,161,92,36,232,192,27,4,79,164,239,33,7,234,134,251,201,183,101,130,16,53,156,159,128,31,114,102,189,93,146,195,240,218,69,200,116,38,100,150,240,83,115,112,26,45,227,187,192,209,78,26,103,205,244,16,222,206,14,44,137,122,90,242,71,18,100,66,54,129,102,204,6,184,67,183,150,113,49,19,39,46,106,155,228,196,172,176,135,28,190,112,244,165,186,8,34,215,198,40,10,137,192,232,115,29,235,232,156,228,111,19,89,114,179,117,98,132,58,185,89,156,198,29,45,146,137,41,250,115,13,199,244,160,255,117,54,88,218,216,139,160,190,127,123,126,254,25,43,124,25,74,41,139,14,191,198,187,212,165,180,77,29,144,169,231,133,47,196,243,254,75,150,175,157,166,54,201,243,112,124,33,125,99,173,107,23,250,204,103,213,56,34,64,50,191,114,45,96,31,33,110,236,211,218,134,80,241,191,124,222,44,145,251,193,30,123,162,41,177,216,208,15,99,198,118,251,82,98,12,60,176,75,25,79,65,45,137,64,17,193,160,121,112,152,249,117,230,118,99,250,66,78,91,9,143,8,108,119,122,27,173,51,28,26,1,146,254,44,31,61,62,99,210,108,192,152,182,249,229,137,201,204,145,160,158,243,0,28,183,47,70,254,173,148,176,222,163,153,84,84,219,73,236,5,141,84,95,183,145,100,96,116,181,35,161,116,168,247,224,235,222,61,179,49,152,119,210,227,244,110,144,87,198,188,203,171,236,93,116,85,21,120,211,255,137,223,28,80,173,206,165,86,229,147,17,194,96,32,48,219,203,162,41,249,221,51,219,130,233,63,208,8,35,103,215,76,230,91,108,153,122,215,220,113,37,81,56,164,80,29,39,14,115,82,137,182,74,123,88,213,156,210,254,45,118,57,158,109,238,114,101,234,187,5,67,172,175,222,242,161,212,62,5,233,205,72,5,204,103,163,67,128,76,14,170,7,42,136,114,115,220,215,182,201,45,42,160,12,113,61,221,240,168,179,89,26,18,225,127,243,110,85,127,16,176,76,206,169,250,188,244,54,185,97,18,132,147,64,151,228,23,222,145,152,151,33,115,231,19,237,52,30,141,20,198,7,148,81,162,245,23,237,98,237,3,27,233,253,93,75,205,201,23,201,187,72,124,38,85,87,217,86,103,112,39,101,199,99,247,129,230,100,5,30,202,105,150,172,39,254,116,147,168,133,30,225,26,34,57,64,88,40,19,147,46,108,222,96,207,136,168,253,131,107,227,179,60,31,154,146,2,162,33,36,158,17,251,184,68,33,95,234,45,141,217,173,114,140,199,224,128,54,244,69,209,144,187,193,89,188,87,208,209,246,37,133,165,74,110,224,222,254,159,31,154,90,72,208,52,109,218,41,185,185,177,248,180,172,227,111,167,51,31,184,234,184,132,157,212,17,154,9,191,193,131,100,197,105,129,55,25,146,97,127,171,7,246,79,93,181,42,214,244,64,141,203,19,170,117,28,43,92,172,129,244,142,247,69,144,34,8,241,17,239,81,56,18,248,150,48,167,252,17,73,189,154,34,169,34,146,94,14,80,185,86,25,130,90,87,166,188,89,99,10,36,28,214,15,109,187,206,166,224,118,186,9,189,121,155,6,100,4,251,197,66,225,69,154,215,130,238,45,103,44,35,56,86,60,101,229,51,172,240,140,148,144,133,46,197,44,227,62,124,251,74,125,176,228,95,187,64,172,152,89,11,62,248,79,223,81,49,16,210,148,14,110,69,217,242,79,45,134,151,12,227,204,5,68,216,86,134,237,247,216,252,162,117,210,183,33,232,216,17,152,124,224,224,162,16,51,157,124,163,33,233,217,155,94,242,176,23,36,238,139,206,34,82,159,98,96,177,163,212,150,
  ];

  String get algorithmName => "Fixed";

  void seed(CipherParameters params) {
  }

  int nextUint8() {
    if( _next>=_values.length ) {
      _next = 0;
    }
    return _values[_next++];
  }
}

Answer 2

In the end, you can use dart.js and the jsencrypt.js JS library (from Tom Wu).

class Rsa
{
  JsObject encryptObj;

  Rsa()
  {
    encryptObj = new JsObject(context['JSEncrypt']);
    encryptObj['default_key_size'] = 1024;
    encryptObj.callMethod('getKey');
  }

  String get publicKey => encryptObj.callMethod('getPublicKey');
  String get privateKey => encryptObj.callMethod('getPrivateKey');

  set publicKey(String key)
  {
    encryptObj.callMethod('setPrivateKey',[key]);
  }

  set privateKey(String key)
  {
    encryptObj.callMethod('setPublicKey',[key]);
  }

  String encrypt(String plainText) => encryptObj.callMethod('encrypt',[plainText]);
  String decrypt(String cipherText) => encryptObj.callMethod('decrypt',[cipherText]);
}