code exchange fixes

pkg/utils/hash.go

@@ -0,0 +1,30 @@
+package utils
+
+import (
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/base64"
+	"fmt"
+	"hash"
+
+	"gopkg.in/square/go-jose.v2"
+)
+
+func GetHashAlgorithm(sigAlgorithm jose.SignatureAlgorithm) (hash.Hash, error) {
+	switch sigAlgorithm {
+	case jose.RS256, jose.ES256, jose.PS256:
+		return sha256.New(), nil
+	case jose.RS384, jose.ES384, jose.PS384:
+		return sha512.New384(), nil
+	case jose.RS512, jose.ES512, jose.PS512:
+		return sha512.New(), nil
+	default:
+		return nil, fmt.Errorf("oidc: unsupported signing algorithm %q", sigAlgorithm)
+	}
+}
+
+func HashString(hash hash.Hash, s string) string {
+	hash.Write([]byte(s)) // hash documents that Write will never return an error
+	sum := hash.Sum(nil)[:hash.Size()/2]
+	return base64.RawURLEncoding.EncodeToString(sum)
+}