Nonce XORing with wider integer types.

src/vfp.c

@@ -54,7 +54,8 @@ struct ece_crypto {
 	unsigned		magic;
 #define ECE_CRYPTO_MAGIC	0xe7f66e91
 	unsigned char		cek[AES128_KEYLEN];
-	unsigned char		prenonce[NONCE_LEN];
+	uint64_t		prenonce_lo;
+	uint32_t		prenonce_hi;
 };
 
 struct ece {
@@ -104,7 +105,7 @@ decrypt_init(struct ece *ece, struct vfp_ctx *ctx)
 {
 	size_t len;
 	uint8_t idlen, *key, hdr[HDR_PREFIX_LEN], id[ID_LEN], prk[SHA256_LEN],
-		cek[SHA256_LEN];
+		cek[SHA256_LEN], prenonce[NONCE_LEN];
 	char errmsg[ERRMSG_LEN];
 	enum vfp_status vp;
 
@@ -159,9 +160,12 @@ decrypt_init(struct ece *ece, struct vfp_ctx *ctx)
 	if (vp == VFP_ERROR)
 		return (vp);
 	if (derive_cek(prk, cek, errmsg) != 0
-	    || derive_prenonce(prk, ece->crypto->prenonce, errmsg) != 0)
+	    || derive_prenonce(prk, prenonce, errmsg) != 0)
 		return (VERR_DEC(ctx, "%s", errmsg));
 
+	ece->crypto->prenonce_hi = vbe32dec(prenonce);
+	ece->crypto->prenonce_lo = vbe64dec(prenonce + 4);
+
 	memcpy(ece->crypto->cek, cek, AES128_KEYLEN);
 	return (VFP_OK);
 }
@@ -183,36 +187,19 @@ seq_inc(struct ece *ece)
 static inline void
 nonce_xor_seq(struct ece *ece, uint8_t *nonce)
 {
-	uint8_t seq[NONCE_LEN];
-
-	CHECK_OBJ_NOTNULL(ece, ECE_MAGIC);
-	CHECK_OBJ_NOTNULL(ece->crypto, ECE_CRYPTO_MAGIC);
-
-	vbe32enc(seq, ece->seq_hi);
-	vbe64enc(seq + 4, ece->seq_lo);
-	for (int i = 0; i < NONCE_LEN; i++)
-		nonce[i] = ece->crypto->prenonce[i] ^ seq[i];
-}
-
-#if 0
-static inline void
-nonce_xor_seq(struct ece *ece, uint8_t *nonce)
-{
-	uint32_t *nonce_hi, *prenonce_hi;
-	uint64_t *nonce_lo, *prenonce_lo;
+	uint32_t nonce_hi;
+	uint64_t nonce_lo;
 
 	CHECK_OBJ_NOTNULL(ece, ECE_MAGIC);
 	CHECK_OBJ_NOTNULL(ece->crypto, ECE_CRYPTO_MAGIC);
+	AN(nonce);
 
-	nonce_hi = (uint32_t *)nonce;
-	prenonce_hi = (uint32_t *)ece->crypto->prenonce;
-	nonce_lo = (uint64_t *)(nonce + 4);
-	prenonce_lo = (uint64_t *)(ece->crypto->prenonce + 4);
+	nonce_hi = ece->crypto->prenonce_hi ^ ece->seq_hi;
+	nonce_lo = ece->crypto->prenonce_lo ^ ece->seq_lo;
 
-	*nonce_hi = *prenonce_hi ^ ece->seq_hi;
-	*nonce_lo = *prenonce_lo ^ ece->seq_lo;
+	vbe32enc(nonce, nonce_hi);
+	vbe64enc(nonce + 4, nonce_lo);
 }
-#endif
 
 static enum vfp_status
 decrypt(struct ece *ece, struct vfp_ctx *ctx, unsigned char *plaintext,