feat(crypto): API for clearing internal caches

crypto/bip32.c

@@ -374,6 +374,13 @@ static CONFIDENTIAL struct {
   HDNode node;
 } private_ckd_cache[BIP32_CACHE_SIZE];
 
+void bip32_cache_clear(void) {
+  private_ckd_cache_root_set = false;
+  private_ckd_cache_index = 0;
+  memzero(&private_ckd_cache_root, sizeof(private_ckd_cache_root));
+  memzero(private_ckd_cache, sizeof(private_ckd_cache));
+}
+
 int hdnode_private_ckd_cached(HDNode *inout, const uint32_t *i, size_t i_count,
                               uint32_t *fingerprint) {
   if (i_count == 0) {

crypto/bip32.h

@@ -89,6 +89,7 @@ void hdnode_public_ckd_address_optimized(const curve_point *pub,
                                          int addrsize, int addrformat);
 
 #if USE_BIP32_CACHE
+void bip32_cache_clear(void);
 int hdnode_private_ckd_cached(HDNode *inout, const uint32_t *i, size_t i_count,
                               uint32_t *fingerprint);
 #endif

crypto/bip39.c

@@ -44,6 +44,11 @@ static CONFIDENTIAL struct {
   uint8_t seed[512 / 8];
 } bip39_cache[BIP39_CACHE_SIZE];
 
+void bip39_cache_clear(void) {
+  memzero(bip39_cache, sizeof(bip39_cache));
+  bip39_cache_index = 0;
+}
+
 #endif
 
 const char *mnemonic_generate(int strength) {

crypto/bip39.h

@@ -27,9 +27,15 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "options.h"
+
 #define BIP39_WORDS 2048
 #define BIP39_PBKDF2_ROUNDS 2048
 
+#if USE_BIP39_CACHE
+void bip39_cache_clear(void);
+#endif
+
 const char *mnemonic_generate(int strength);  // strength in bits
 const char *mnemonic_from_data(const uint8_t *data, int len);
 void mnemonic_clear(void);