gojwtjwt-go

How to extract the claims from JWT token


I'm using the dgrijalva/jwt-go/ package.

I would like to extract the payload from the token, and I couldn't find a way to do it.


Example (taken from : https://jwt.io/):

for encoded:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ

I would like to extract the payload:

{
  "sub": "1234567890",
  "name": "John Doe",
  "admin": true
}

I will be grateful for an example (using golang).


Solution

  • Sample Code:

        func extractClaims(tokenStr string) (jwt.MapClaims, bool) {
            hmacSecretString := // Value
            hmacSecret := []byte(hmacSecretString)
            token, err := jwt.Parse(tokenStr, func(token *jwt.Token) (interface{}, error) {
                 // check token signing method etc
                 return hmacSecret, nil
            })
    
            if err != nil {
                return nil, false
            }
    
            if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
                return claims, true
            } else {
                log.Printf("Invalid JWT Token")
                return nil, false
            }
        }