Variable: jwksCache

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• const jwksCache: unique symbol

Symbol used to configure an externally persisted remote JWKS cache.

[!WARNING]
Only trusted application code must be allowed to write this cache; its keys are trusted for signature verification.

This option is intended for cloud computing runtimes that cannot keep an in memory cache between their code's invocations. The supplied writable object seeds the resolver's cache and is updated with jwks and uat after a successful fetch; persist it whenever uat changes. Using this in runtimes that can keep an in-memory cache between requests is not desirable.

When passed to createRemoteJWKSet this allows the passed in object to:

• Serve as an initial value for the JSON Web Key Set that the module would otherwise need to trigger an HTTP request for
• Have the JSON Web Key Set the function optionally ended up triggering an HTTP request for assigned to it as properties

The intended use pattern is:

• Before verifying with createRemoteJWKSet you pull the previously cached object from a low-latency key-value store offered by the cloud computing runtime it is executed on;
• Default to an empty object {} instead when there's no previously cached value;
• Pass it in as [jwksCache];
• Afterwards, update the key-value storage if the uat property of the object has changed.

Example

// Prerequisites
let url!: URL
let jwt!: string
let getPreviouslyCachedJWKS!: () => Promise<jose.ExportedJWKSCache>
let storeNewJWKScache!: (cache: jose.ExportedJWKSCache) => Promise<void>

// Load JSON Web Key Set cache
const jwksCache: jose.JWKSCacheInput = (await getPreviouslyCachedJWKS()) || {}
const { uat } = jwksCache

const JWKS = jose.createRemoteJWKSet(url, {
  [jose.jwksCache]: jwksCache,
})

// Use JSON Web Key Set cache
await jose.jwtVerify(jwt, JWKS)

if (uat !== jwksCache.uat) {
  // Update JSON Web Key Set cache
  await storeNewJWKScache(jwksCache)
}