如何从 Flutter 中的 RSA 私钥生成令牌？

Question

Hi Guys I am really confused about so many things.All I know is that I have to generate a token at the end of the day.I am given some RSA private key which is some "XYZ............dsdsfm",(obviously I can't reveal it because of security issues),from there I have to generate some token which will serve as a header for authorisation of my API http request.

The problem is these internet related stuff of JsonWebKey and all that is not in my domain,but still I tried learning them but it is not very clear.I tried to implement some code which was written in Java by someone (and that guy knows only Java and not flutter),in flutter.

For Flutter implementation I tried two plugin in pub.dev...But I am not getting the proper output.

The first one was https://pub.dev/packages/jose>I tried what is similar in the example page of it as shown:

import 'dart:convert';
import 'dart:io';

import 'package:crypto_keys/crypto_keys.dart';
import 'package:jose/jose.dart';
import 'package:x509/x509.dart';

String pkey="XXXXXXXXXXXXXsfds";

void keyGenerator() async {
 //await example1();
  await example2();
//  await example3();
//  await example4();
//  await example5();
 // await example6();
//  await example7();
//  await example8();
}

// decode and verify a JWS
void example1() async {
  var encoded = pkey;

  // create a JsonWebSignature from the encoded string
  var jws = JsonWebSignature.fromCompactSerialization(encoded);

  // extract the payload
  var payload = jws.unverifiedPayload;

  print('content of jws: ${payload.stringContent}');
  print('protected parameters: ${payload.protectedHeader.toJson()}');

  // create a JsonWebKey for verifying the signature
  var jwk = JsonWebKey.fromJson({
    'kty': 'RSA',
    'alg': 'RS256',

  });
  var keyStore = JsonWebKeyStore()..addKey(jwk);

  // verify the signature
  var verified = await jws.verify(keyStore);
  print('signature verified: $verified');
}

// create a JWS
void example2() async {
  // create a builder
  var builder = JsonWebSignatureBuilder();

  // set the content
  builder.stringContent = 'It is me';

  // set some protected header
  builder.setProtectedHeader('createdAt', DateTime.now().toIso8601String());

  // add a key to sign, you can add multiple keys for different recipients
  builder.addRecipient(
      JsonWebKey.fromJson({
        'kty': 'RSA',
        'kid': pkey,
      }),
      algorithm: 'RS256');

  // build the jws
  var jws = builder.build();

  // output the compact serialization
  print('jws compact serialization: ${jws.toCompactSerialization()}');

  // output the json serialization
  print('jws json serialization: ${jws.toJson()}');
}

// decode and decrypt a JWE
void example3() async {
  var encoded = 'eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.'
      'UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm'
      '1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc'
      'HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF'
      'NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8'
      'rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv'
      '-B3oWh2TbqmScqXMR4gp_A.'
      'AxY8DCtDaGlsbGljb3RoZQ.'
      'KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.'
      '9hH0vgRfYgPnAHOd8stkvw';

  // create a JsonWebEncryption from the encoded string
  var jwe = JsonWebEncryption.fromCompactSerialization(encoded);

  // create a JsonWebKey for decrypting the signature
  var jwk = JsonWebKey.fromJson(
    {
      'kty': 'RSA',
      'n': 'sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl'
          'UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre'
          'cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_'
          '7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI'
          'Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU'
          '7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw',
      'e': 'AQAB',
      'd': 'VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq'
          '1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry'
          'nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_'
          '0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj'
          '-VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj'
          'T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ',
      'p': '9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68'
          'ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP'
          'krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM',
      'q': 'uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y'
          'BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN'
          '-3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0',
      'dp': 'w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv'
          'ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra'
          'Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs',
      'dq': 'o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff'
          '7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_'
          'odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU',
      'qi': 'eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC'
          'tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ'
          'B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo'
    },
  );
  var keyStore = JsonWebKeyStore()..addKey(jwk);

  // decrypt the payload
  var payload = await jwe.getPayload(keyStore);
  print('decrypted content: ${payload.stringContent}');
}

// create a JWE
void example4() async {
  // create a builder
  var builder = JsonWebEncryptionBuilder();

  // set the content
  builder.stringContent = 'This is my bigest secret';

  // set some protected header
  builder.setProtectedHeader('createdAt', DateTime.now().toIso8601String());

  // add a key to encrypt the Content Encryption Key
  var jwk = JsonWebKey.fromJson(
    {
      'kty': 'RSA',
      'n': 'sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl'
          'UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre'
          'cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_'
          '7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI'
          'Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU'
          '7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw',
      'e': 'AQAB',
      'd': 'VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq'
          '1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry'
          'nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_'
          '0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj'
          '-VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj'
          'T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ',
      'p': '9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68'
          'ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP'
          'krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM',
      'q': 'uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y'
          'BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN'
          '-3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0',
      'dp': 'w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv'
          'ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra'
          'Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs',
      'dq': 'o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff'
          '7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_'
          'odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU',
      'qi': 'eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC'
          'tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ'
          'B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo'
    },
  );
  builder.addRecipient(jwk, algorithm: 'RSA1_5');

  // set the content encryption algorithm to use
  builder.encryptionAlgorithm = 'A128CBC-HS256';

  // build the jws
  var jwe = builder.build();

  // output the compact serialization
  print('jwe compact serialization: ${jwe.toCompactSerialization()}');

  // output the json serialization
  print('jwe json serialization: ${jwe.toJson()}');
}

// decode and verify and validate a JWT
void example5() async {
  var encoded = 'eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.'
      'eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt'
      'cGxlLmNvbS9pc19yb290Ijp0cnVlfQ.'
      'dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk';

  // decode the jwt, note: this constructor can only be used for JWT inside JWS
  // structures
  var jwt = JsonWebToken.unverified(encoded);

  // output the claims
  print('claims: ${jwt.claims}');

  // create key store to verify the signature
  var keyStore = JsonWebKeyStore()
    ..addKey(JsonWebKey.fromJson({
      'kty': 'oct',
      'k':
      'AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow'
    }));

  var verified = await jwt.verify(keyStore);
  print('verified: $verified');

  // alternatively, create and verify the JsonWebToken together, this is also
  // applicable for JWT inside JWE
  jwt = await JsonWebToken.decodeAndVerify(encoded, keyStore);

  // validate the claims
  var violations = jwt.claims.validate(issuer: Uri.parse('alice'));
  print('violations: $violations');
}

// create a JWT
void example6() async {
  var claims = JsonWebTokenClaims.fromJson({
    'exp': Duration(hours: 4).inSeconds,
    'aud':"live-tv",
    'iat':DateTime.now().toString(),

  });

  // create a builder, decoding the JWT in a JWS, so using a
  // JsonWebSignatureBuilder
  var builder = JsonWebSignatureBuilder();

  // set the content
  builder.jsonContent = claims.toJson();

  // add a key to sign, can only add one for JWT
  builder.addRecipient(
      JsonWebKey.fromJson({
        'kty': 'RSA',
        'kid':pkey,
         }),

      algorithm: 'HS256');

  // build the jws
  var jws = builder.build();

  // output the compact serialization
  print('jwt compact serialization: ${jws.toCompactSerialization()}');
}

// create a JWT, sign with RS512
void example7() async {
  var claims = JsonWebTokenClaims.fromJson({
    'exp': Duration(hours: 4).inSeconds,
    'iss': 'alice',
  });

  // create a builder, decoding the JWT in a JWS, so using a
  // JsonWebSignatureBuilder
  var builder = JsonWebSignatureBuilder();

  // set the content
  builder.jsonContent = claims.toJson();

  // add a key to sign, can only add one for JWT
  var key = JsonWebKey.fromPem(File('example/jwtRS512.key').readAsStringSync());
  builder.addRecipient(key, algorithm: 'RS512');

  // build the jws
  var jws = builder.build();

  // output the compact serialization
  print('jwt compact serialization: ${jws.toCompactSerialization()}');
}

// generate a key for use with ES256 signing
void example8() async {
  var alg = JsonWebAlgorithm.getByName('ES256');

  var key = alg.generateRandomKey();
  print(JsonEncoder.withIndent(' ').convert(key));

  final hash = utf8.encode('TEST');

  var sig = key.sign(hash);
  final valid = key.verify(hash, sig);

  print('valid? $valid');
}

I tried each example at a time modifying each of those.Few of them said saying "Compact serialisation should have 3 parts",then I did a bit of research and realised that the token to be generated should have 3 parts.The other error in example 2 was that the JSONWebKey can't be signed.

There is another library I used and that was https://pub.dev/packages/corsac_jwt .

The code is below:

import 'package:corsac_jwt/corsac_jwt.dart';
//  ..setClaim('13', {'userId': 'xxxx'})

String pkey="sdfdsfdsfds";

void tokenGenerator() {

  var builder = new JWTBuilder();
  var token = builder
    ..audience="live-tv"
    ..issuedAt= new DateTime.now()
    ..expiresAt = new DateTime.now().add(new Duration(minutes: 3))

    ..getToken(); // returns token without signature

 var signer = new JWTRsaSha256Signer(privateKey: pkey);

  var signedToken = builder.getSignedToken(signer);
  print("token");
      print(signedToken); // prints encoded JWT
  var stringToken = signedToken.toString();

  var decodedToken = new JWT.parse(stringToken);
  // Verify signature:
  print(decodedToken.verify(signer)); // true

  // Validate claims:
//  var validator = new JWTValidator() ;// uses DateTime.now() by default
//   // set claims you wish to validate
//  Set<String> errors = validator.validate(decodedToken);
//  print(errors); // (empty list)
}

But here I got the error invalid private key.If I changed it to public,I got invalid public key as well.

I honestly am I a very chaotic situation mentally with time running out to implement.My team mates are know only one thing I know only flutter only.

By the way the Java code we are trying to implement in flutter is given below.Basically what it does is it takes a StringKey,converts to a PrivateKey and then the token

import android.util.Log;

import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Date;
import java.util.concurrent.TimeUnit;


public class RSAKeyGenerator {
    private static PrivateKey getPrivateKey() throws GeneralSecurityException {
        String pKey = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
        KeyFactory kf = KeyFactory.getInstance("RSA");
        byte[] decode;
        decode = android.util.Base64.decode(pKey, android.util.Base64.DEFAULT);
        PKCS8EncodedKeySpec keySpecPKCS8 = new PKCS8EncodedKeySpec(decode);
        return kf.generatePrivate(keySpecPKCS8);
    }
    public static String getJwtToken() {
        final long VALIDITY_MS = TimeUnit.MINUTES.toMillis(60);
        long nowMillis = System.currentTimeMillis();
        Date now = new Date(nowMillis);
        Date exp = new Date(nowMillis + VALIDITY_MS);
        PrivateKey privateKey = null;
        try {
            privateKey = getPrivateKey();
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }
        String jws = Jwts.builder()
                .claim("version", "13")
                .claim("user_id", "xxxxxxxxxxxxxxxxxxx")
                .setIssuedAt(now)
                .setExpiration(exp)
                .signWith(privateKey, SignatureAlgorithm.RS256)
                .setAudience("live-tv")
                .compact();
        Log.d("111__", jws);
        SpUtil.Companion.getInstance().putString(J_TOKEN, jws);
        return jws;
    }
}

Answer 1

After hours of research,trial and errors and consulting my team mates I have arrived at the final conclusion.This works.The mistake I was doing was the RSA key I was passing it as a string like key="xxxxxxxxxxxx",but it should be in the format below

Hope this helps someone

import 'package:dart_jsonwebtoken/dart_jsonwebtoken.dart';

String token;

String dartJsonWebTokenGenerator() {
  Duration delay = new Duration(minutes: 300);
  final jwt = JWT(
    payload: {
      'version': '13',
      'user_id': 'xxxxxxxxxxxxxxxxx',
    },
    audience: 'live-tv',
  );

// Sign it (default with HS256 algorithm)
  token = jwt.sign(PrivateKey('''-----BEGIN RSA PRIVATE KEY-----
                      xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx7
                      wIxAoKDcHD7mv2R//I0QncGzT1I7cccrhIUB1gXH9wWdTXrafhACXrJ2Drfjg/YN
                      9q4TiKH1k2+zTfdU1IDxd6OX2cPNkwn/vpZeZ1pZqVoimRRJbJg8RhXYvZgd6Nfj
                      Zdw6LY3Zzm3XbLbTUmbVM5ARDweksnr6cg7HmR2OQ5j5UFuhRyIUTSCDbAmDeyHS
                      xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx70YmgZPR
                      PIncbKBjLzQe5RB/szyswCAiLxfk7rCrUhPpvdJ4fnDgdXQE26t/CBFb8fpOHtiL
                      1FtxgURmX/Nh+OhO7pPvK4X7g2GarMdQ3Y6288/STQu/d8yEQDwcro6X9ribay46
                      Ss69AGJxGJbazUI9fNMETLpR6kIHKli7G7gtTFVY02YPKpqgYs1HFbIgV++gHTaw
                      XLU3PqroxKkhTuI8JCei1pphS/PAc3S/o0mPxTYLfiojYG/6IDd8WsGonwwk2hqd
                      e3ad0S56JZNN812vshc8NFMbEU2UzA7L0INf6X+GAhoZojUjZciKwAN/iF9YV0cU
                      XorRDXcXrXn7hpqAzDq/jMQO78jr2MyaY/dfiSVp6sTS8gNMCuz0g3I7gSkCAwEA
                      AQKCAgEAiPWqK/qdrFYR4unJwU9ouonlMWGl0BAndIUEcjIt4cPCVwtfuL+aE98q
                      J8MJYINVTgaJ7VbnKnSkARQkuUYWCLhYF8z9hq+h3Ce2QPJMhwC1GCT3MFGMQQRD
                      wP/U8q99k9xljOAckw6TnxjTFJCoFUQrbA9QcXb9ypSMvvorMDGzR+5X99IMsGFj
                      elwJJS4v7fV3oWZsoMcfAcuFlrAETNPjkaX0CmaIru/CaMupq7YQUa6CmMhwQwUJ
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                      Yvj0JmozTlXCCQMCggEBAOqzcuIdix5kvU871T0m1vpMXYIA5+0NolqW/PNQYzQj
                      f55Kwyzlx6BNBKxCvgCoo9YYKRWKq0wN1H0CUvOFxBwu4h/XJqDtc6yM58UYImTG
                      ZWFVJI4GvB0jdTw3F4LMOnEgl2zMQB17Yf7p2WUIFpUowQC5ZEvFa16cYMKRCoPz
                      4RH1p83eDEok2XQSHlZH1hZHG6YlBlMiBPW0904xICnm8dT73jTijaNKrlV5E9FQ
                      IS0tl3Gc6aVEdd/r89ArHYByjRdLN3IXzy8BOLGFtT8/+PB7egdUPEejTNiIGKWo
                      hvWVp6wEyjdOh+zI1X4L1oVXqxBVajTSFk0qxqW2V2MCggEAJK4KK1lJybthiI/7
                      GQ1CAzQon6m+fg+CSIE0jVgbIw/rumFjxM/l4Dct8759FKZ4lkkKKCSXV5QMClQc
                      xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxW
                      Qq/prxwXr/TUer7SzQXcfcMYdsjwougGeG6yYLZrT/FuOURoHDztEyOqZUeDU2zJ
                      Zdv6UGZfIsdHhcgGaE8B2l3ujkxIU6bGy3JRLETF80B9brHvIeKchpqom037LFuY
                      X7EKORMbp9R3jJ5eFG9TmTcCzXBtW6Aa2yH2RZzDNZ/1d+xhxEQzZVnyCEz/RhUI
                      Dd6EDQKCAQEAmpjDpt/xAH85F9UAvDw2RT9CJN016Dcf524nhppADlsHuBvk/lEJ
                      MrUoy9NW1pY+/UqC3XavKPS/L+z0+QX2zN2xA2o0PrLKjDFwhapFFX59zyRHZOpY
                      xRTTJ2vep8ChCl1+gSL1ZLYeMcyV72/peC0VHMYBo8uR0wtMzTy+4XYmni7jbr7B
                      96DYQBWjOBAvnBMQylr/FImHHNYsRKwlVJSUXUfe8ZT92T7bIOAVRr3ybJDofeTv
                      Hna+8lW5DzknQLGz8FESX6wBRCQY1Q6O+e/IqZecJPG+ly2g88yJ96zP4TrH7I5n
                      KREohbcwsctYbhL2UlcBE3QDTqdLnGJEowKCAQBwlBtw/BD5cefTcUB90XtuUpLG
                      xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                      moP4L4wBlad2aZYKnkZ87RZIa09wyf5hnPXQkQAHMRYxuaxvQUq/bSDO6JUbrGMp
                      J2LQgCreNAF7MsIDU2ijVHJNWp9m6LC1Osb1iMp/fZDy+hkAAHP5xDfDedwKmXLV
                      2kSdWPZebq1iIRyJ+BlbXAEgDMkp+k6mebq+kyH4+3odWvw8bRkmD/g1t/bS
                      -----END RSA PRIVATE KEY-----'''),
      algorithm: JWTAlgorithm.RS256, expiresIn: delay);
  print('Signed token: $token\n');
  return token;
}