use of device key with AES-GCM and add way to avoid malloc for tag

Author: JacobBarthelmeh

wolfcrypt/src/port/xilinx/xil-aesgcm.c

@@ -135,7 +135,9 @@ int wc_AesGcmSetKey_ex(Aes* aes, const byte* key, word32 len, word32 kup)
     aes->xKeySize =
             len == AES_128_KEY_SIZE ? XSECURE_AES_KEY_SIZE_128 :
                                       XSECURE_AES_KEY_SIZE_256;
-    XMEMCPY(aes->keyInit, key, len);
+    if (key != NULL) {
+        XMEMCPY(aes->keyInit, key, len);
+    }
 
     return 0;
 }
@@ -478,7 +480,12 @@ int  wc_AesGcmSetKey_ex(Aes* aes, const byte* key, word32 len, word32 kup)
 {
     XCsuDma_Config* con;
 
-    if (aes == NULL || key == NULL) {
+    if (aes == NULL) {
+        return BAD_FUNC_ARG;
+    }
+
+    if (kup == XSECURE_CSU_AES_KEY_SRC_KUP && key == NULL) {
+        WOLFSSL_MSG("Expecting key buffer passed in if using KUP");
         return BAD_FUNC_ARG;
     }
 
@@ -501,7 +508,9 @@ int  wc_AesGcmSetKey_ex(Aes* aes, const byte* key, word32 len, word32 kup)
 
     aes->keylen = len;
     aes->kup    = kup;
-    XMEMCPY((byte*)(aes->keyInit), key, len);
+    if (key != NULL) {
+        XMEMCPY((byte*)(aes->keyInit), key, len);
+    }
 
     return 0;
 }
@@ -538,18 +547,26 @@ int  wc_AesGcmEncrypt(Aes* aes, byte* out,
             return BAD_FUNC_ARG;
         }
 
+    #ifndef NO_WOLFSSL_XILINX_TAG_MALLOC
         tmp = (byte*)XMALLOC(sz + AES_GCM_AUTH_SZ, aes->heap,
             DYNAMIC_TYPE_TMP_BUFFER);
         if (tmp == NULL) {
             return MEMORY_E;
         }
+    #else
+        /* if NO_WOLFSSL_XILINX_TAG_MALLOC is defined than it is assumed that
+         * out buffer is large enough to hold both the cipher out and tag */
+        tmp = out;
+    #endif
 
         XSecure_AesInitialize(&(aes->xilAes), &(aes->dma), aes->kup, (word32*)iv,
             aes->keyInit);
         XSecure_AesEncryptData(&(aes->xilAes), tmp, in, sz);
-        XMEMCPY(out, tmp, sz);
         XMEMCPY(authTag, tmp + sz, authTagSz);
+    #ifndef NO_WOLFSSL_XILINX_TAG_MALLOC
+        XMEMCPY(out, tmp, sz);
         XFREE(tmp, aes->heap, DYNAMIC_TYPE_TMP_BUFFER);
+    #endif
     }
 
     /* handle completing tag with any additional data */

wolfssl/wolfcrypt/aes.h

@@ -85,10 +85,14 @@ WOLFSSL_LOCAL void GHASH(Gcm* gcm, const byte* a, word32 aSz, const byte* c,
 #ifdef WOLFSSL_XILINX_CRYPT_VERSAL
 #include <wolfssl/wolfcrypt/port/xilinx/xil-versal-glue.h>
 #include <xsecure_aesclient.h>
-#define WOLFSSL_XILINX_AES_KEY_SRC XSECURE_AES_USER_KEY_0
+#if !defined(WOLFSSL_XILINX_AES_KEY_SRC)
+    #define WOLFSSL_XILINX_AES_KEY_SRC XSECURE_AES_USER_KEY_0
+#endif
 #else /* versal */
 #include <xsecure_aes.h>
-#define WOLFSSL_XILINX_AES_KEY_SRC XSECURE_CSU_AES_KEY_SRC_KUP
+#if !defined(WOLFSSL_XILINX_AES_KEY_SRC)
+    #define WOLFSSL_XILINX_AES_KEY_SRC XSECURE_CSU_AES_KEY_SRC_KUP
+#endif
 #endif /* !versal */
 #endif /* WOLFSSL_XILINX_CRYPT */
 

wolfssl/wolfcrypt/settings.h

@@ -1844,7 +1844,10 @@ extern void uITRON4_free(void *p) ;
     #if !defined(WOLFSSL_XILINX_CRYPT_VERSAL)
         #define NO_DEV_RANDOM
     #endif
+    #undef  NO_WOLFSSL_DIR
     #define NO_WOLFSSL_DIR
+
+    #undef  HAVE_AESGCM
     #define HAVE_AESGCM
 #endif