nearformfast-jwt
Fast JSON Web Token implementation.
Installation
Just run:
npm install fast-jwtUsage
createSigner
Create a signer function by calling createSigner and providing one or more of the following options:
key: A string or a buffer containing the secret forHS*algorithms or the PEM encoded private key forRS*,PS*,ES*andEdDSAalgorithms. If thekeyis a passphrase protected private key it must be an object (more details below). The key can also be a function accepting a Node style callback or a function returning a promise. This is the only mandatory option, which MUST NOT be provided if the token algorithm isnone.algorithm: The algorithm to use to sign the token. The default value is autodetected from the key, usingRS256for RSA private keys,HS256for plain secrets and the correspondingESorEdDSAalgorithms for EC or Ed* private keys.mutatePayload: If set totrue, the original payload will be modified in place (viaObject.assign) by the signing function. This is useful if you need a raw reference to the payload after claims have been applied to it but before it has been encoded into a token. Default isfalse.expiresIn: Time span (in milliseconds or text describing time) after which the token expires, added as theexpclaim in the payload as defined by the section 4.1.4 of RFC 7519. This will override any existing value in the claim.Eg:
60,"2 days","10h","7d". A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc), otherwise milliseconds unit is used by default ("120"is equal to"120ms"). For more info look into @lukeed/ms.notBefore: Time span (in milliseconds or text describing time) before the token is active, added as thenbfclaim in the payload as defined by the section 4.1.5 of RFC 7519. This will override any existing value in the claim.Eg:
60,"2 days","10h","7d". A numeric value is interpreted as a seconds count. If you use a string be sure you provide the time units (days, hours, etc), otherwise milliseconds unit is used by default ("120"is equal to"120ms"). For more info look into @lukeed/ms.jti: The token unique identifier, added as thejticlaim in the payload as defined by the section 4.1.7 of RFC 7519. This will override any existing value in the claim.aud: The token audience, added as theaudclaim in the payload as defined by the section 4.1.3 of RFC 7519. This claim identifies the recipients that the token is intended for. It must be a string or an array of strings. This will override any existing value in the claim.iss: The token issuer, added as theissclaim in the payload as defined by the section 4.1.1 of RFC 7519. It must be a string. This will override any existing value in the claim.sub: The token subject, added as thesubclaim in the payload as defined by the section 4.1.2 of RFC 7519. It must be a string. This will override any existing value in the claim.nonce: The token nonce, added as thenonceclaim in the payload. Thenoncevalue is used to associate a Client session with an ID Token. Note that this is a IANA JSON Web Token Claims Registry public claim registered by OpenID Connect (OIDC). It must be a string. This will override any existing value in the claim.kid: The token key id, added as thekidclaim in the header section (see section 4.1.4 of RFC 7515 and section 4.5 of RFC 7517). It must be a string.header: Additional claims to add to the header section. This will override thetypandkidclaims.noTimestamp: If set totrue, theiatclaim should not be added to the token. Default isfalse.clockTimestamp: The timestamp in milliseconds (like the output ofDate.now()) that should be used as the current time for all necessary time comparisons. Default is the system time.
The signer is a function which accepts a payload and returns the token.
The payload must be an object.
If the key option is a function, the signer will also accept a Node style callback and will return a promise, supporting therefore both callback and async/await styles.
If the key is a passphrase protected private key, the algorithm option must be provided and must be either a RS* or ES* encoded key and the key option must be an object with the following structure:
{
key: '<YOUR_RSA_ENCRYPTED_PRIVATE_KEY>',
passphrase: '<PASSPHRASE_THAT_WAS_USED_TO_ENCRYPT_THE_PRIVATE_KEY>'
}Example
const { createSigner } = require('fast-jwt')
// Sync style
const signSync = createSigner({ key: 'secret' })
const token = signSync({ a: 1, b: 2, c: 3 })
// => eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9.mIcxteEVjbh2MnKQ3EQlojZojGSyA_guqRBYHQURcfnCSSBTT2OShF8lo9_ogjAv-5oECgmCur_cDWB7x3X53g
// Callback style
const signWithCallback = createSigner({ key: (callback) => callback(null, 'secret') })
signWithCallback({ a: 1, b: 2, c: 3 }, (err, token) => {
// token === eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9.mIcxteEVjbh2MnKQ3EQlojZojGSyA_guqRBYHQURcfnCSSBTT2OShF8lo9_ogjAv-5oECgmCur_cDWB7x3X53g
})
// Promise style - Note that the key function style and the signer function style are unrelated
async function test() {
const signWithPromise = createSigner({ key: async () => 'secret' })
const token = await signWithPromise({ a: 1, b: 2, c: 3 })
// => eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9.mIcxteEVjbh2MnKQ3EQlojZojGSyA_guqRBYHQURcfnCSSBTT2OShF8lo9_ogjAv-5oECgmCur_cDWB7x3X53g
}
// Using password protected private key - in this case you MUST provide the algorithm as well
const signSync = createSigner({
algorithm: '<ANY_RS*_OR_ES*_ALGORITHM>',
key: {
key: '<YOUR_RSA_ENCRYPTED_PRIVATE_KEY>',
passphrase: '<PASSPHRASE_THAT_WAS_USED_TO_ENCRYPT_THE_PRIVATE_KEY>'
})
const token = signSync({ a: 1, b: 2, c: 3 })createDecoder
Create a decoder function by calling createDecoder and providing one or more of the following options:
complete: Return an object with the decoded header, payload, signature and input (the token part before the signature), instead of just the content of the payload. Default isfalse.checkTyp: When validating the decoded header, setting this option forces the check of thetypproperty against this value. Example:checkTyp: 'JWT'. Default isundefined.
The decoder is a function which accepts a token (as Buffer or string) and returns the payload or the sections of the token.
Examples
const { createDecoder } = require('fast-jwt')
const token =
'eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9.mIcxteEVjbh2MnKQ3EQlojZojGSyA_guqRBYHQURcfnCSSBTT2OShF8lo9_ogjAv-5oECgmCur_cDWB7x3X53g'
// Standard decoder
const decode = createDecoder()
const payload = decode(token)
// => { a: 1, b: 2, c: 3, iat: 1579521212 }
// Complete decoder
const decodeComplete = createDecoder({ complete: true })
const sections = decodeComplete(token)
/* =>
{
header: { alg: 'HS512', typ: 'JWT' },
payload: { a: 1, b: 2, c: 3, iat: 1579521212 },
signature: 'mIcxteEVjbh2MnKQ3EQlojZojGSyA/guqRBYHQURcfnCSSBTT2OShF8lo9/ogjAv+5oECgmCur/cDWB7x3X53g==',
input: 'eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9'
}
*/createVerifier
Create a verifier function by calling createVerifier and providing one or more of the following options:
key: A string or a buffer containing the secret forHS*algorithms or the PEM encoded public key forRS*,PS*,ES*andEdDSAalgorithms. The key can also be a function accepting a Node style callback or a function returning a promise. This is the only mandatory option, which MUST NOT be provided if the token algorithm isnone.algorithms: List of strings with the names of the allowed algorithms. By default, all algorithms are accepted.complete: Return an object with the decoded header, payload, signature and input (the token part before the signature), instead of just the content of the payload. Default isfalse.cache: A positive number specifying the size of the verified tokens cache (using LRU strategy). Setting totrueis equivalent to provide the size1000. When enabled, as you can see in the benchmarks section below, performances dramatically improve. By default the cache is disabled.cacheTTL: The maximum time to live of a cache entry (in milliseconds). If the token has a earlier expiration or the verifier has a shortermaxAge, the earlier takes precedence. The default is600000, which is 10 minutes.errorCacheTTL: A number or functionfunction (tokenError) => numberthat represents the maximum time to live of a cache error entry (in milliseconds). Example: thekeyfunction fails or does not return a secret or public key. By default errors are not cached, theerrorCacheTTLdefault value is-1.allowedJti: A string, a regular expression, an array of strings or an array of regular expressions containing allowed values for the id claim (jti). By default, all values are accepted.allowedAud: A string, a regular expression, an array of strings or an array of regular expressions containing allowed values for the audience claim (aud). By default, all values are accepted.allowedIss: A string, a regular expression, an array of strings or an array of regular expressions containing allowed values for the issuer claim (iss). By default, all values are accepted.allowedSub: A string, a regular expression, an array of strings or an array of regular expressions containing allowed values for the subject claim (sub). By default, all values are accepted.allowedNonce: A string, a regular expression, an array of strings or an array of regular expressions containing allowed values for the nonce claim (nonce). By default, all values are accepted.requiredClaims: An array of strings containing which claims should exist in the token. By default, no claim is marked as required.ignoreExpiration: Do not validate the expiration of the token. Default isfalse.ignoreNotBefore: Do not validate the activation of the token. Default isfalse.maxAge: The maximum allowed age (in milliseconds) for tokens to still be valid. By default this is not checked.clockTimestamp: The timestamp in milliseconds (like the output ofDate.now()) that should be used as the current time for all necessary time comparisons. Default is the system time.clockTolerance: Timespan in milliseconds is the tolerance to apply to the current timestamp when performing time comparisons. Default is0.cacheKeyBuilder: The function that will be used to create the cache's key for each token. To mitigate the risk of leaking sensitive information and generate collisions, a hashing function is used by default.
The verifier is a function which accepts a token (as Buffer or string) and returns the payload or the sections of the token.
If the key option is a function, the signer will also accept a Node style callback and will return a promise, supporting therefore both callback and async/await styles.
Examples
const { createVerifier, TOKEN_ERROR_CODES } = require('fast-jwt')
const token =
'eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9.mIcxteEVjbh2MnKQ3EQlojZojGSyA_guqRBYHQURcfnCSSBTT2OShF8lo9_ogjAv-5oECgmCur_cDWB7x3X53g'
// Sync style
const verifySync = createVerifier({ key: 'secret' })
const payload = verifySync(token)
// => { a: 1, b: 2, c: 3, iat: 1579521212 }
// Callback style with complete return
const verifyWithCallback = createVerifier({ key: callback => callback(null, 'secret'), complete: true })
verifyWithCallback(token, (err, sections) => {
/*
sections === {
header: { alg: 'HS512', typ: 'JWT' },
payload: { a: 1, b: 2, c: 3, iat: 1579521212 },
signature: 'mIcxteEVjbh2MnKQ3EQlojZojGSyA/guqRBYHQURcfnCSSBTT2OShF8lo9/ogjAv+5oECgmCur/cDWB7x3X53g==',
input: 'eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhIjoxLCJiIjoyLCJjIjozLCJpYXQiOjE1Nzk1MjEyMTJ9'
}
*/
})
// Promise style - Note that the key function style and the verifier function style are unrelated
async function test() {
const verifyWithPromise = createVerifier({ key: async () => 'secret' })
const payload = await verifyWithPromise(token)
// => { a: 1, b: 2, c: 3, iat: 1579521212 }
}
// custom errorCacheTTL verifier
const verifier = createVerifier({
key: 'secret',
cache: true,
errorCacheTTL: tokenError => {
// customize the ttl based on the error code
if (tokenError.code === TOKEN_ERROR_CODES.invalidKey) {
return 1000
}
return 2000
}
})Creating a certificate
Many different algorithms are supported and appropriate certificates can be created through various external applications. Here is one example to create RSA certificates with openssl.
PRIVATE_PEM="./jwt-private.pem"
PUBLIC_PEM="./jwt-public.pem"
ssh-keygen -t rsa -b 2048 -m PEM -f "$PRIVATE_PEM" -q -N ""
openssl rsa -in "$PRIVATE_PEM" -pubout -outform PEM -out "$PUBLIC_PEM" 2>/dev/null
rm "$PRIVATE_PEM.pub"Algorithms supported
This is the lisf of currently supported algorithms:
| Name | Description |
|---|---|
none |
Empty algorithm - The token signature section will be empty |
HS256 |
HMAC using SHA-256 hash algorithm |
HS384 |
HMAC using SHA-384 hash algorithm |
HS512 |
HMAC using SHA-512 hash algorithm |
ES256 |
ECDSA using P-256 curve and SHA-256 hash algorithm |
ES384 |
ECDSA using P-384 curve and SHA-384 hash algorithm |
ES512 |
ECDSA using P-521 curve and SHA-512 hash algorithm |
RS256 |
RSASSA-PKCS1-v1_5 using SHA-256 hash algorithm |
RS384 |
RSASSA-PKCS1-v1_5 using SHA-384 hash algorithm |
RS512 |
RSASSA-PKCS1-v1_5 using SHA-512 hash algorithm |
PS256 |
RSASSA-PSS using SHA-256 hash algorithm |
PS384 |
RSASSA-PSS using SHA-384 hash algorithm |
PS512 |
RSASSA-PSS using SHA-512 hash algorithm |
EdDSA |
EdDSA tokens using Ed25519 or Ed448 keys, only supported on Node.js 12+ |
Caching
fast-jwt supports caching of verified tokens.
The cache layer, powered by mnemonist, is a LRU cache which dimension is controlled by the user, as described in the options list.
When caching is enabled, verified tokens are always stored in cache. If the verification fails once, the error is cached as well for the time set by errorCacheTTL and the operation is not retried.
For verified tokens, caching considers the time sensitive claims of the token (iat, nbf and exp) and make sure the verification is retried after a token becomes valid or after a token becomes expired.
Performances improvements varies by uses cases and by the type of the operation performed and the algorithm used.
The default cacheKeyBuilder is a function that hashes the token. This provides a good level of protection against sensitive information leaks, but it also has a significant performance impact (almost 10x slower, as it's a CPU bound operation). If you are using caching and you are not concerned about potential information leaks you can use the identity function as cacheKeyBuilder to improve them.
For a detailed discussion about it, take a look at this issue.
Note: Errors are not cached by default, to change this behaviour use the
errorCacheTTLoption.
Token Error Codes
Error codes exported by TOKEN_ERROR_CODES.
Error Handling
When using the verifier, errors can occur due to various reasons such as an expired token, an invalid signature, or a malformed token. fast-jwt throws a TokenError when such issues are encountered. You can catch this error and inspect its code property to determine the specific cause of the error. The possible values for the code property are listed in the TOKEN_ERROR_CODES object (see the "Token Error Codes" section above for more details).
const { createVerifier, createSigner, TOKEN_ERROR_CODES } = require('fast-jwt')
// Example 1: Handling an expired token
const sign = createSigner({ key: 'secret', expiresIn: '1ms' }) // Token expires almost immediately
const verify = createVerifier({ key: 'secret' })
const expiredToken = sign({ foo: 'bar' })
// Wait for a moment to ensure the token expires
setTimeout(() => {
try {
verify(expiredToken)
} catch (err) {
if (err.code === TOKEN_ERROR_CODES.expired) {
console.error('Token verification failed because the token has expired.')
// Handle expired token error (e.g., prompt user to re-authenticate)
} else {
console.error('An unexpected error occurred:', err.message)
}
}
}, 100); // Wait 100ms, which is longer than the token's 1ms validity
// Example 2: Handling an invalid signature (e.g., wrong secret)
const correctSigner = createSigner({ key: 'correct-secret' })
const verifierWithWrongKey = createVerifier({ key: 'wrong-secret' })
const tokenSignedWithCorrectKey = correctSigner({ data: 'payload' })
try {
verifierWithWrongKey(tokenSignedWithCorrectKey)
} catch (err) {
if (err.code === TOKEN_ERROR_CODES.invalidSignature) {
console.error('Token verification failed due to an invalid signature. This might be due to a key mismatch.')
// Handle invalid signature error
} else {
console.error('An unexpected error occurred:', err.message)
}
}JWKS
JWKS is supported via get-jwks. Check out the documentation for integration examples.
Benchmarks
See benchmarks
Contributing
See CONTRIBUTING.md
License
Licensed under the Apache-2.0 license.
