The function decodes a JSON Web Token (JWT).
Synopsis
string jwtDecode(string jwt, string key [, string algorithm] [, bool ignoreSignature = false]); Parameters
| Parameter | Description |
| jwt | The JWT token. |
| key | The key, which was used to sign the JWT token. |
| algorithm | The optional parameter specifying the expected signing algorithm used to decode the JWT. Decoding will only work if these algorithms match. Possible values and the default value are the same as forjwtEncode(). Similarly, the use of "RSxxx" values means that the key must contain the public RSA key matching the private RSA key used for signing. |
| ignoreSignature | Decides if the signature is used or not. |
Description
The function returns the payload contained in the string "jwt", if it has been signed with "key", using the signing algorithm "HS256". If any problems are encountered (e.g.: invalid signature, wrong key, token not correctly encoded), an empty string is returned. The error details can be read with getLastError().
If the parameter "ignoreSignature" is set to "true", the the payload of the JWT token is also returned when key is wrong (or just an empty string). When this flag is set, it is not checked whether the JWT token contains valid information or has been manipulated, so the information in the payload cannot be trusted.
"algorithm":
Although the JWT header contains the name of the algorithm that was used for signing, this alone is not sufficient to securely determine the signing algorithm used, because attackers could modify this information and create a token signed with a different algorithm. For backwards compatibility, all the following combinations of parameters are valid:
- jwtDecode(jwt, key);
- jwtDecode(jwt, key, ignoreSignature);
- jwtDecode(jwt, key, algorithm);
- jwtDecode(jwt, key, algorithm, ignoreSignature);
For "RSxx" algorithms, a RSA public/private key pair is needed. These will normally be read from a file, e.g.:
string priKey, pubKey;fileToString(getPath(DATA_REL_PATH, "jwt_private_key.pem"), priKey);fileToString(getPath(DATA_REL_PATH, "jwt_public_key.pem"), pubKey);string jwt = jwtEncode(payloadToEncode, priKey, "RS256");string payload = jwtDecode(jwtToDecode, pubKey, "RS256");
CAUTION: In a production system, the private key must not be stored within the project directory structure.
FAQs
Signature verification failed, meaning the JWT verification failed, either because its signature is invalid, the key is invalid, the token is expired or it's been tampered with.
Is it possible to decrypt a JWT token? ›
By design, anyone can decode a JWT and read the contents of the header and payload sections. However, we need access to the secret key used to create the signature to verify a token's integrity.
What is the jwtDecode method? ›
jwtDecode() The function jsonDecode() decodes a JSON encoded string variable. The function encodes data into an JSON format string. The function decodes a JSON Web Token (JWT).
Is JWT secure enough? ›
It's important to remember that JWT safety depends greatly on how you use and validate tokens. Just because a JWT contains a cryptographic signature it doesn't automatically mean that it's valid, or that you should blindly trust it. Your APIs can become vulnerable to cyber-attacks unless you observe good practices.
Is JWT bad for authentication? ›
It's important to note that a JWT guarantees data ownership but not encryption. The reason is that the JWT can be seen by anyone who intercepts the token because it's serialized, not encrypted. It is strongly advised to use JWTs with HTTPS, a practice that extends to general web security.
How do I fix an invalid signature in JWT? ›
For Invalid JWT Signature, check if your service account key has expired. Go to your APIs & Services to add a new key if it has.
Can you decode a JWT without secret? ›
When decoding a JWT token, only the payload is decoded, which contains the actual data and is not encrypted. However, decoding the payload does not verify the token's signature. Without the secret key, you cannot verify the token's authenticity or prevent tampering.
Is JWT token hackable? ›
It is used literally everywhere: from sessions to token-based authentication in OAuth, to custom authentication of all shapes and forms. There is actually a pretty good reason for this wide adoption and that is, for the most part, security and resilience. However, just like any technology, JWT is not immune to hacking.
How to check if a JWT token is valid? ›
To verify JWT claims
- Decode the token and compare the exp claim to the current time.
- If your access token includes an aws. cognito. signin. user. admin claim, send a request to an API like GetUser. ...
- Present your access token in a request to the UserInfo endpoint. Your request returns an error if your token has expired.
Basics of JWT and How to Decode JWT tokens in node?
- Open an empty folder in vs code.
- Open terminal.
- Create a package.json by using “npm init”
- Include 'jsonwebtoken' in project by using “npm install jsonwebtoken”
- Create 'index.js' file.
- Import 'jsonwebtoken' in file: “const jwt = require('jsonwebtoken')”
Procedure
- Use OpenSSL to create a private key, where <user> is the name for your key identity. openssl genrsa -out <user>Private.pem.
- Create a public key. openssl rsa -in <user>Private.pem -pubout -out <user>Pub.pem.
- View the keys by listing the keys to ensure that they are created. ls -l.
@bsrour You don't “decode” a refresh token. Refresh tokens are just strings. You use refresh tokens to extend the lifetime of an OAuth access token. If either the access token or refresh token have expired, then the user will need to authorise your application again.
Is JWT obsolete? ›
In May 2023, Adobe announced the deprecation and end of life of Service Account (JWT) credentials. This means that any of your integrations or custom applications using a Service Account (JWT) credential will need to migrate to the new OAuth Server-to-Server credential before January 27, 2025.
Why avoid JWT? ›
JWTs which just store a simple session token are inefficient and less flexible than a regular session cookie, and don't gain you any advantage. The JWT specification itself is not trusted by security experts.
Which is better JWT or OAuth? ›
JWT is simple and easy to learn from the initial stage while OAuth is complex. OAuth uses both client-side and server-side storage while JWT must use only client-side storage. JWT has limited scope and use cases. OAuth is highly flexible and can be easily used in a wide range of situations.
What could cause a digital signature verification failure? ›
If it is showing the error of " one or more signatures need validation" (At the topmost area). Then you need to validate your signature in the reader itself by clicking on the signature > Signature Properties> Show Signature Certificate> Trust> Add to trusted certificates> Tick all the options and save your file.
How to verify signature in JWT token? ›
Verify JWT
- Download the public key for the keypair you have used to sign the hash from DigiCert® Software Trust Manager .
- Access jwt.io debugger.
- Paste your JWT token into the Encoded box.
- Paste the public key into the Verify Signature box.
The JWT signature is not being verified by the server. If the JWT is used to control access to the application, an attacker could take advantage of this vulnerability to forge a token and impersonate other users or even elevate privileges.
What should I do if my digital signature is not verified? ›
If the signature is not valid, you can take appropriate action, such as contacting the signer to request a new signature. You can also download a verification report for future reference by clicking on the 'Download Report' button in the Verify E-Sign dialog box.
