Sort-of-working, large (4096-bit) RSA keys broken.

Snapshot of mostly but not entirely working code to include the extra
ModExpA7 key components in the keystore.  Need to investigate whether
a more compact representation is practical for these components, as
the current one bloats the key object so much that a bare 4096-bit key
won't fit in a single hash block, and there may not be enough room for
PKCS #11 attributes even for smaller keys.

If more compact representation not possible or insufficient, the other
option is to double the size of a keystore object, making it two flash
subsectors for a total of 8192 octets.  Which would of course halve
the number of keys we can store and require a bunch of little tweaks
all through the ks code (particularly flash erase), so definitely
worth trying for a more compact representation first.

1 files changed, 12 insertions, 2 deletions

diff --git a/hal.h b/hal.h
index b7eae72..f7a7522 100644
--- a/hal.h
+++ b/hal.h
@@ -479,8 +479,6 @@ extern hal_error_t hal_rsa_private_key_to_der(const hal_rsa_key_t * const key,
 extern hal_error_t hal_rsa_private_key_to_der_extra(const hal_rsa_key_t * const key,
                                                     uint8_t *der, size_t *der_len, const size_t der_max);
 
-extern size_t hal_rsa_private_key_to_der_len(const hal_rsa_key_t * const key);
-
 extern hal_error_t hal_rsa_private_key_from_der(hal_rsa_key_t **key,
                                                 void *keybuf, const size_t keybuf_len,
                                                 const uint8_t * const der, const size_t der_len);
@@ -496,6 +494,18 @@ extern hal_error_t hal_rsa_public_key_from_der(hal_rsa_key_t **key,
 
 extern int hal_rsa_key_needs_saving(const hal_rsa_key_t * const key);
 
+static inline size_t hal_rsa_private_key_to_der_len(const hal_rsa_key_t * const key)
+{
+  size_t len = 0;
+  return hal_rsa_private_key_to_der(key, NULL, &len, 0) == HAL_OK ? len : 0;
+}
+
+static inline size_t hal_rsa_private_key_to_der_extra_len(const hal_rsa_key_t * const key)
+{
+  size_t len = 0;
+  return hal_rsa_private_key_to_der_extra(key, NULL, &len, 0) == HAL_OK ? len : 0;
+}
+
 /*
  * ECDSA.
  */