Add 3DS hashing support (#298)

include/rc_hash.h

@@ -123,6 +123,28 @@ RC_BEGIN_C_DECLS
   RC_EXPORT void RC_CCONV rc_hash_init_default_cdreader(void);
   RC_EXPORT void RC_CCONV rc_hash_init_custom_cdreader(struct rc_hash_cdreader* reader);
 
+  /* specifies a function called to obtain a 3DS CIA decryption normal key.
+   * this key would be derived from slot0x3DKeyX and the common key specified by the passed index.
+   * the normal key should be written in big endian format
+   * returns non-zero on success, or zero on failure.
+   */
+  typedef int (RC_CCONV *rc_hash_3ds_get_cia_normal_key_func)(uint8_t common_key_index, uint8_t out_normal_key[16]);
+  RC_EXPORT void RC_CCONV rc_hash_init_3ds_get_cia_normal_key_func(rc_hash_3ds_get_cia_normal_key_func func);
+
+  /* specifies a function called to obtain 3DS NCCH decryption normal keys.
+   * the primary key will always use slot0x2CKeyX and the passed primary KeyY.
+   * the secondary key will use the KeyX slot passed
+   * the secondary KeyY will be identical to the primary keyY if the passed program id is NULL
+   * if the program id is not null, then the secondary KeyY will be obtained with "seed crypto"
+   * with "seed crypto" the 8 byte program id can be used to obtain a 16 byte "seed" within the seeddb.bin firmware file
+   * the primary KeyY then the seed will then be hashed with SHA256, and the upper 16 bytes of the digest will be the secondary KeyY used
+   * the normal keys should be written in big endian format
+   * returns non-zero on success, or zero on failure.
+   */
+  typedef int (RC_CCONV *rc_hash_3ds_get_ncch_normal_keys_func)(uint8_t primary_key_y[16], uint8_t secondary_key_x_slot, uint8_t* optional_program_id,
+                                                                uint8_t out_primary_key[16], uint8_t out_secondary_key[16]);
+  RC_EXPORT void RC_CCONV rc_hash_init_3ds_get_ncch_normal_keys_func(rc_hash_3ds_get_ncch_normal_keys_func func);
+
   /* ===================================================== */
 
 RC_END_C_DECLS