Add per-function override for AES

include/mbedtls/aes.h

@@ -246,6 +246,32 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
                        unsigned char *output );
 #endif /* MBEDTLS_CIPHER_MODE_CTR */
 
+/**
+ * \brief           Internal AES block encryption function
+ *                  (Only exposed to allow overriding it,
+ *                  see MBEDTLS_AES_ENCRYPT_ALT)
+ *
+ * \param ctx       AES context
+ * \param input     Plaintext block
+ * \param output    Output (ciphertext) block
+ */
+void mbedtls_aes_encrypt( mbedtls_aes_context *ctx,
+                          const unsigned char input[16],
+                          unsigned char output[16] );
+
+/**
+ * \brief           Internal AES block decryption function
+ *                  (Only exposed to allow overriding it,
+ *                  see MBEDTLS_AES_DECRYPT_ALT)
+ *
+ * \param ctx       AES context
+ * \param input     Ciphertext block
+ * \param output    Output (plaintext) block
+ */
+void mbedtls_aes_decrypt( mbedtls_aes_context *ctx,
+                          const unsigned char input[16],
+                          unsigned char output[16] );
+
 #ifdef __cplusplus
 }
 #endif

include/mbedtls/config.h

@@ -241,6 +241,10 @@
  * of mbedtls_sha1_context, so your implementation of mbedtls_sha1_process must be compatible
  * with this definition.
  *
+ * Note: if you use the AES_xxx_ALT macros, then is is recommended to also set
+ * MBEDTLS_AES_ROM_TABLES in order to help the linker garbage-collect the AES
+ * tables.
+ *
  * Uncomment a macro to enable alternate implementation of the corresponding
  * function.
  */
@@ -254,6 +258,10 @@
 //#define MBEDTLS_DES_SETKEY_ALT
 //#define MBEDTLS_DES_CRYPT_ECB_ALT
 //#define MBEDTLS_DES3_CRYPT_ECB_ALT
+//#define MBEDTLS_AES_SETKEY_ENC_ALT
+//#define MBEDTLS_AES_SETKEY_DEC_ALT
+//#define MBEDTLS_AES_ENCRYPT_ALT
+//#define MBEDTLS_AES_DECRYPT_ALT
 
 /**
  * \def MBEDTLS_AES_ROM_TABLES