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chore: parse jwks in config initialisation
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,152 @@ | ||
| package conf | ||
|
|
||
| import ( | ||
| "crypto/ecdsa" | ||
| "crypto/ed25519" | ||
| "crypto/rsa" | ||
| "crypto/x509" | ||
| "encoding/base64" | ||
| "encoding/json" | ||
| "fmt" | ||
|
|
||
| "github.com/lestrrat-go/jwx/v2/jwk" | ||
| ) | ||
|
|
||
| type JwtKeysDecoder map[string]JwkInfo | ||
|
|
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| type JwkInfo struct { | ||
| PublicKey jwk.Key `json:"public_key"` | ||
| PrivateKey jwk.Key `json:"private_key"` | ||
| } | ||
|
|
||
| type KeyInfo struct { | ||
| Type string `json:"type"` | ||
| PrivateKey string `json:"private_key"` | ||
| InUse bool `json:"in_use"` | ||
| } | ||
|
|
||
| // Decode implements the Decoder interface | ||
| // which transforms the keys stored as der binary strings into jwks | ||
| func (j *JwtKeysDecoder) Decode(value string) error { | ||
| data := map[string]KeyInfo{} | ||
| if err := json.Unmarshal([]byte(value), &data); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| config := JwtKeysDecoder{} | ||
| for kid, key := range data { | ||
| // all private keys should be stored as der binary strings in base64 | ||
| derBytes, err := base64.StdEncoding.DecodeString(key.PrivateKey) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| var privKey any | ||
| if key.Type == "hmac" { | ||
| privKey = derBytes | ||
| } else { | ||
| // assume key is asymmetric | ||
| privKey, err = x509.ParsePKCS8PrivateKey(derBytes) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| } | ||
| alg := getAlg(privKey) | ||
| if alg == "" { | ||
| return fmt.Errorf("unsupported key alg: %v", kid) | ||
| } | ||
|
|
||
| privJwk, err := jwk.FromRaw(privKey) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| // Set kid, alg and use claims for private key | ||
| if err := privJwk.Set(jwk.KeyIDKey, kid); err != nil { | ||
| return err | ||
| } | ||
| if err := privJwk.Set(jwk.AlgorithmKey, alg); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| switch key.InUse { | ||
| case true: | ||
| // only the key that's in use should be used for encryption | ||
| if err := privJwk.Set(jwk.KeyUsageKey, "enc"); err != nil { | ||
| return err | ||
| } | ||
| default: | ||
| if err := privJwk.Set(jwk.KeyUsageKey, "sig"); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
||
| pubJwk, err := jwk.PublicKeyOf(privJwk) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| // public keys are always used for signature verification only | ||
| if err := pubJwk.Set(jwk.KeyUsageKey, "sig"); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| config[kid] = JwkInfo{ | ||
| PublicKey: pubJwk, | ||
| PrivateKey: privJwk, | ||
| } | ||
| } | ||
| *j = config | ||
| return nil | ||
| } | ||
|
|
||
| func (j *JwtKeysDecoder) Validate() error { | ||
| // Validate performs _minimal_ checks if the data stored in the key are valid. | ||
| // By minimal, we mean that it does not check if the key is valid for use in | ||
| // cryptographic operations. For example, it does not check if an RSA key's | ||
| // `e` field is a valid exponent, or if the `n` field is a valid modulus. | ||
| // Instead, it checks for things such as the _presence_ of some required fields, | ||
| // or if certain keys' values are of particular length. | ||
| // | ||
| // Note that depending on th underlying key type, use of this method requires | ||
| // that multiple fields in the key are properly populated. For example, an EC | ||
| // key's "x", "y" fields cannot be validated unless the "crv" field is populated first. | ||
| for _, key := range *j { | ||
| if err := key.PrivateKey.Validate(); err != nil { | ||
| return err | ||
| } | ||
| if err := key.PublicKey.Validate(); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func getAlg(key any) string { | ||
| var alg string | ||
| switch p := key.(type) { | ||
| case []byte: | ||
| alg = "HS256" | ||
| case *ecdsa.PrivateKey: | ||
| switch p.Curve.Params().Name { | ||
| case "P-256": | ||
| alg = "ES256" | ||
| case "P-384": | ||
| alg = "ES384" | ||
| case "P-521": | ||
| alg = "ES512" | ||
| } | ||
| case *rsa.PrivateKey: | ||
| switch p.N.BitLen() { | ||
| case 2048: | ||
| alg = "RS256" | ||
| case 4096: | ||
| alg = "RS512" | ||
| } | ||
| case *ed25519.PrivateKey: | ||
| // Ed25519 is still experimental based on https://github.com/lestrrat-go/jwx/tree/develop/v2/jwk#supported-key-types | ||
| alg = "EdDSA" | ||
| default: | ||
| return "" | ||
| } | ||
| return alg | ||
| } |