sha3: Make sure state and rate input buffers are 8-byte aligned

Both buffers are accessed directly by casting to `uint64_t`.  On platforms
that don't allow unaligned accesses this could cause a SIGBUS.  The
reorder should avoid extra padding between the two buffers.

Fixes: 5ff88c9622 ("xof: Implemented SHAKE128 and SHAKE256 Extended Output Functions")
Fixes: 83c1883d0b ("Use word-aligned XOR in sha3_absorb()")

src/libstrongswan/plugins/sha3/sha3_keccak.c

@@ -59,18 +59,18 @@ struct private_sha3_keccak_t {
 	/**
 	 * Internal state of 1600 bits as defined by FIPS-202
 	 */
-	uint8_t state[KECCAK_STATE_SIZE];
+	uint8_t state[KECCAK_STATE_SIZE] __attribute__((aligned(8)));
+
+	/**
+	 * Rate input buffer
+	 */
+	uint8_t rate_buffer[KECCAK_MAX_RATE] __attribute__((aligned(8)));
 
 	/**
 	 * Rate in bytes
 	 */
 	u_int rate;
 
-	/**
-	 * Rate input buffer
-	 */
-	uint8_t rate_buffer[KECCAK_MAX_RATE];
-
 	/**
 	 * Index pointing to the current position in the rate buffer
 	 */