updated as per the review comments

pkg/plugin/definition/signer.go

@@ -8,7 +8,6 @@ type Signer interface {
 	// The signature is created with the given timestamps: createdAt (signature creation time)
 	// and expiresAt (signature expiration time).
 	Sign(ctx context.Context, body []byte, privateKeyBase64 string, createdAt, expiresAt int64) (string, error)
-	Close() error // Close for releasing resources
 }
 
 // SignerProvider initializes a new signer instance with the given config.
@@ -16,9 +15,3 @@ type SignerProvider interface {
 	// New creates a new signer instance based on the provided config.
 	New(ctx context.Context, config map[string]string) (Signer, func() error, error)
 }
-
-// PrivateKeyManager is the interface for key management plugin.
-type PrivateKeyManager interface {
-	// PrivateKey retrieves the private key for the given subscriberID and keyID.
-	PrivateKey(ctx context.Context, subscriberID string, keyID string) (string, error)
-}