String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkJhZWxkdW5nIFVzZXIiLCJpYXQiOjE1MTYyMzkwMjJ9.qH7Zj_m3kY69kxhaQXTa-ivIpytKXXjZc1ZSmapZnGE";
String[] chunks = token.split("\\.");
Base64.Decoder decoder = Base64.getUrlDecoder();
String header = new String(decoder.decode(chunks[0]));
String payload = new String(decoder.decode(chunks[1]));
System.out.println(header);
//{"alg":"HS256","typ":"JWT"}
System.out.println(payload);
//{"sub":"1234567890","name":"Baeldung User","iat":1516239022}
<dependency>
<groupId>io.jsonwebtoken</groupId>
<artifactId>jjwt</artifactId>
<version>0.7.0</version>
</dependency>
// Configuring Signature Algorithm and Key Specification
SignatureAlgorithm sa = HS256;
SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getBytes(), sa.getJcaName());
// Performing the Verification
String tokenWithoutSignature = chunks[0] + "." + chunks[1];
String signature = chunks[2];
DefaultJwtSignatureValidator validator = new DefaultJwtSignatureValidator(sa, secretKeySpec);
if (!validator.isValid(tokenWithoutSignature, signature)) {
throw new Exception("Could not verify JWT token integrity!");
}
