Move encrypt cache to stack

This avoids claiming a large amount of RAM when using libwolfboot from the app.

Author: danielinux

src/libwolfboot.c

@@ -1339,12 +1339,13 @@ int wolfBoot_fallback_is_possible(void)
 #endif
 
 
-
 #ifdef NVM_FLASH_WRITEONCE
 #define ENCRYPT_CACHE NVM_CACHE
 #else
+#ifdef WOLFBOOT_SMALL_STACK
 static uint8_t ENCRYPT_CACHE[NVM_CACHE_SIZE] __attribute__((aligned(32)));
 #endif
+#endif
 
 #if defined(EXT_ENCRYPTED) && defined(MMU)
 static uint8_t ENCRYPT_KEY[ENCRYPT_KEY_SIZE + ENCRYPT_NONCE_SIZE];
@@ -1356,6 +1357,11 @@ static int RAMFUNCTION hal_set_key(const uint8_t *k, const uint8_t *nonce)
     int ret = 0;
     int sel_sec = 0;
     uint32_t trailer_relative_off = 4;
+
+#if !defined(WOLFBOOT_SMALL_STACK) && !defined(NVM_FLASH_WRITEONCE)
+    uint8_t ENCRYPT_CACHE[NVM_CACHE_SIZE] __attribute__((aligned(32)));
+#endif
+
 #ifdef MMU
     XMEMCPY(ENCRYPT_KEY, k, ENCRYPT_KEY_SIZE);
     XMEMCPY(ENCRYPT_KEY + ENCRYPT_KEY_SIZE, nonce, ENCRYPT_NONCE_SIZE);
@@ -1692,6 +1698,9 @@ int RAMFUNCTION ext_flash_encrypt_write(uintptr_t address, const uint8_t *data,
     int sz = len, i, step;
     uint8_t part;
     uint32_t iv_counter = 0;
+#if defined(EXT_ENCRYPTED) && !defined(WOLFBOOT_SMALL_STACK) && !defined(NVM_FLASH_WRITEONCE)
+    uint8_t ENCRYPT_CACHE[NVM_CACHE_SIZE] __attribute__((aligned(32)));
+#endif
 
     row_offset = address & (ENCRYPT_BLOCK_SIZE - 1);
     if (row_offset != 0) {