Top JWT(JSON Web Token) frequently asked interview questions.
Q: What is need for JWT?
A :- JWT stands for JSON Web Token
- It is pronounced as JAWT
- It is Open Standard - RFC7519
- JWT makes it possible to communicate securely between two bodies
- JWT is used for Authorization
Understanding the need for JSON Web Token(JWT)
Q: What are the advantages of JWT?
A :Advantages of JWT Authorization
- JWT is self contained. It is a value token. So during each validation the Gmail server does not needs to fetch the information corresponding to it.
- It is digitally signed so if any one modifies it the server will know about it
- It is most suitable for Microservices Architecture
- It has other advantages like specifying the expiration time.
Q: What is the structure of JWT?
A : A JWT consists of 3 parts -
- Header
- Payload
- Signature
Q: What is expiration date of JWT?
A : Expiration Time - This the time for which we want the generated JWT to be valid for. This will be in milliseconds. Suppose we want the JWT to be valid for 5 hours, then we will specify this value as 18000000Q: How do we specify expiration date of JWT?
A :
private String doGenerateToken(Map<String, Object> claims, String subject) {
return Jwts.builder().setClaims(claims).setSubject(subject).setIssuedAt(new Date(System.currentTimeMillis()))
.setExpiration(new Date(System.currentTimeMillis() + jwtExpirationInMs)).signWith(SignatureAlgorithm.HS512, secret).compact();
}
See Also
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