A Go library to retrieve RSA public keys from a JWKS (JSON Web Key Set) endpoint.
Using Go modules
go get github.com/guftall/go-jwks@v0.2.0
github.com/square/go-jose
- JWT librarygithub.com/patrickmn/go-cache
- default in-memory cache
GetEncryptionKey
returns *jose.JSONWebKey
for a given key id:
package main
import (
"github.com/guftall/go-jwks"
"github.com/square/go-jose"
"time"
"log"
)
func main() {
jwksSource := jwks.NewWebSource("https://www.googleapis.com/oauth2/v3/certs")
jwksClient := jwks.NewDefaultClient(
jwksSource,
time.Hour, // Refresh keys every 1 hour
12*time.Hour, // Expire keys after 12 hours
)
var jwk *jose.JSONWebKey
jwk, err := jwksClient.GetEncryptionKey("c6af7caa0895fd01e778dceaa7a7988347d8f25c")
if err != nil {
log.Fatal(err)
}
log.Printf("key: %v, alg: %v, use: %v", jwk.KeyID, jwk.Algorithm, jwk.Use)
}
Log:
2018/07/30 01:22:35 Fetchng JWKS from https://www.googleapis.com/oauth2/v3/certs
2018/07/30 01:22:36 key: c6af7caa0895fd01e778dceaa7a7988347d8f25c, alg: RS256, use: sig
There are two caching parameters:
refresh
- the key will be fetched from the source after this intervalttl
- if not used, the key will be deleted from cache
On the first request, the key is synchronously fetched from the key server and stored in the cache.
On the next request after refresh
interval, the key will be refreshed in the background (not affect response time).
Only 1 key refresh is executed at the same time.
If the key is not requested during ttl
interval, it will be removed from cache.
Default cache is github.com/patrickmn/go-cache
in-memory cache.
You can provide your own cache implementation, see cache.go
:
type Cache interface {
// Get an item from the cache and itsexpiration time.
// Returns the item or nil, and a bool indicating whether the key was found
GetWithExpiration(k string) (interface{}, time.Time, bool)
// Add an item to the cache, replacing any existing item.
Set(k string, x interface{})
}
and pass it to func NewClient(...)
Default source is WebSource
. You can provide your own implementation, see source.go
:
type JWKSSource interface {
JSONWebKeySet() (*jose.JSONWebKeySet, error)
}