1. JWTHelper:
2. public String generateToken(String payload, Key key) {
3.         return builderFactory
4.                 .createJwtBuilder()
5.                 .setPayload(payload)
6.                 .setHeaderParam("typ", "JWT")
7.                 .setHeaderParam("alg", signatureAlgorithm.getValue())
8.                 .signWith(key, signatureAlgorithm)
9.                 .compact();
10.     }
11.  
12. Caller statement: OAuthService
13. String strPrivateKey = encryptionUtilities.aesDecrypt(toolConfiguration.getPlatformPrivateKey(),
14.                     aesSecretKey);
15. PrivateKey privateKey = encryptionUtilities.string2PrivateKey(strPrivateKey);
16.             long startTime = System.currentTimeMillis();
17.             String accessToken = jwtHelper.generateToken(payload, privateKey, tokenExpirationInMilliSeconds);
18.             LOGGER.info("Time spend in getOauthToken jwtHelper.generateToken {}", System.currentTimeMillis() - startTime);
19.  
20.  
21. EncryptionUtil.java
22. public PrivateKey string2PrivateKey(String privateKeyString) {
23.         long startTime = System.currentTimeMillis();
24.         try {
25.             KeyFactory kf = KeyFactory.getInstance(ServiceConstants.RSA);
26.             PKCS8EncodedKeySpec keySpecPKCS8 = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(privateKeyString));
27.             PrivateKey privateKey = kf.generatePrivate(keySpecPKCS8);
28.             LOGGER.info("Time spend in string2PrivateKey {}", System.currentTimeMillis() - startTime);
29.             return privateKey;
30.         } catch (IllegalArgumentException | InvalidKeySpecException | NoSuchAlgorithmException e) {
31.             LOGGER.error(e.getMessage(), e);
32.             return null;
33.         }
34.     }
35.  
36.