Removed unused key field from njs_hmac_t.
diff --git a/src/njs_crypto.c b/src/njs_crypto.c
index 9a3d384..273eff1 100644
--- a/src/njs_crypto.c
+++ b/src/njs_crypto.c
@@ -36,7 +36,6 @@
 } njs_digest_t;
 
 typedef struct {
-    njs_str_t           key;
     u_char              opad[64];
 
     union {