1 files changed, 20 insertions, 0 deletions
diff --git a/internal/util/crypto.go b/internal/util/crypto.go
new file mode 100644
index 0000000..2a29628
--- /dev/null
+++ b/internal/util/crypto.go
@@ -0,0 +1,20 @@
+package util
+
+import (
+	"crypto"
+	"crypto/ed25519"
+	"fmt"
+
+	"git.sigsum.org/sigsum-go/pkg/hex"
+)
+
+func SignerFromHex(s string) (crypto.Signer, error) {
+	b, err := hex.Deserialize(s)
+	if err != nil {
+		return nil, fmt.Errorf("util: parse key: %v", err)
+	}
+	if len(b) != ed25519.PrivateKeySize {
+		return nil, fmt.Errorf("util: invalid private key size %d", len(b))
+	}
+	return ed25519.PrivateKey(b), nil
+}