diff --git a/pkg/plugin/implementation/signer/signer.go b/pkg/plugin/implementation/signer/signer.go
index c1f2af9..90bc6a4 100644
--- a/pkg/plugin/implementation/signer/signer.go
+++ b/pkg/plugin/implementation/signer/signer.go
@@ -48,11 +48,12 @@ func generateSignature(signingString []byte, privateKeyBase64 string) ([]byte, e
 		return nil, fmt.Errorf("error decoding private key: %w", err)
 	}
 
-	if len(privateKeyBytes) != ed25519.PrivateKeySize {
-		return nil, errors.New("invalid private key length")
+	if len(privateKeyBytes) != ed25519.SeedSize {
+		return nil, errors.New("invalid seed length")
 	}
 
-	privateKey := ed25519.PrivateKey(privateKeyBytes)
+	// Generate the private key from the seed
+	privateKey := ed25519.NewKeyFromSeed(privateKeyBytes)
 	return ed25519.Sign(privateKey, signingString), nil
 }
 
diff --git a/pkg/plugin/implementation/signer/signer_test.go b/pkg/plugin/implementation/signer/signer_test.go
index 6a25da1..ebcbbb6 100644
--- a/pkg/plugin/implementation/signer/signer_test.go
+++ b/pkg/plugin/implementation/signer/signer_test.go
@@ -12,7 +12,7 @@ import (
 // generateTestKeys generates a test private and public key pair in base64 encoding.
 func generateTestKeys() (string, string) {
 	publicKey, privateKey, _ := ed25519.GenerateKey(nil)
-	return base64.StdEncoding.EncodeToString(privateKey), base64.StdEncoding.EncodeToString(publicKey)
+	return base64.StdEncoding.EncodeToString(privateKey.Seed()), base64.StdEncoding.EncodeToString(publicKey)
 }
 
 // TestSignSuccess tests the Sign method with valid inputs to ensure it produces a valid signature.
@@ -82,7 +82,7 @@ func TestSignFailure(t *testing.T) {
 			privateKey:      base64.StdEncoding.EncodeToString([]byte("short_key")),
 			createdAt:       time.Now().Unix(),
 			expiresAt:       time.Now().Unix() + 3600,
-			expectErrString: "invalid private key length",
+			expectErrString: "invalid seed length",
 		},
 	}