Add per-function override for AES

ChangeLog

@@ -4,9 +4,9 @@ mbed TLS ChangeLog (Sorted per branch, date)
 
 Features
   * Support for DTLS 1.0 and 1.2 (RFC 6347).
-  * Ability to override xxx_process() function from a md/sha module with
+  * Ability to override core functions from MDx, SHAx, AES and DES modules
-    custom implementation (eg hardware accelerated), complementing the ability
+    with custom implementation (eg hardware accelerated), complementing the
-    to override the whole module.
+    ability to override the whole module.
 
 API Changes
    * All public identifiers moved to the mbedtls_* or MBEDTLS_* namespace.

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

library/aes.c

@@ -481,6 +481,7 @@ void mbedtls_aes_free( mbedtls_aes_context *ctx )
 /*
  * AES key schedule (encryption)
  */
+#if !defined(MBEDTLS_AES_SETKEY_ENC_ALT)
 int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
                     unsigned int keysize )
 {
@@ -589,10 +590,12 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
 
     return( 0 );
 }
+#endif /* !MBEDTLS_AES_SETKEY_ENC_ALT */
 
 /*
  * AES key schedule (decryption)
  */
+#if !defined(MBEDTLS_AES_SETKEY_DEC_ALT)
 int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
                     unsigned int keysize )
 {
@@ -656,6 +659,7 @@ exit:
 
     return( ret );
 }
+#endif /* !MBEDTLS_AES_SETKEY_DEC_ALT */
 
 #define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)     \
 {                                               \
@@ -703,6 +707,120 @@ exit:
                  RT3[ ( Y0 >> 24 ) & 0xFF ];    \
 }
 
+/*
+ * AES-ECB block encryption
+ */
+#if !defined(MBEDTLS_AES_ENCRYPT_ALT)
+void mbedtls_aes_encrypt( mbedtls_aes_context *ctx,
+                          const unsigned char input[16],
+                          unsigned char output[16] )
+{
+    int i;
+    uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
+
+    RK = ctx->rk;
+
+    GET_UINT32_LE( X0, input,  0 ); X0 ^= *RK++;
+    GET_UINT32_LE( X1, input,  4 ); X1 ^= *RK++;
+    GET_UINT32_LE( X2, input,  8 ); X2 ^= *RK++;
+    GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++;
+
+    for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
+    {
+        AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
+        AES_FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
+    }
+
+    AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
+
+    X0 = *RK++ ^ \
+            ( (uint32_t) FSb[ ( Y0       ) & 0xFF ]       ) ^
+            ( (uint32_t) FSb[ ( Y1 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) FSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) FSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
+
+    X1 = *RK++ ^ \
+            ( (uint32_t) FSb[ ( Y1       ) & 0xFF ]       ) ^
+            ( (uint32_t) FSb[ ( Y2 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) FSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) FSb[ ( Y0 >> 24 ) & 0xFF ] << 24 );
+
+    X2 = *RK++ ^ \
+            ( (uint32_t) FSb[ ( Y2       ) & 0xFF ]       ) ^
+            ( (uint32_t) FSb[ ( Y3 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) FSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) FSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
+
+    X3 = *RK++ ^ \
+            ( (uint32_t) FSb[ ( Y3       ) & 0xFF ]       ) ^
+            ( (uint32_t) FSb[ ( Y0 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) FSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) FSb[ ( Y2 >> 24 ) & 0xFF ] << 24 );
+
+    PUT_UINT32_LE( X0, output,  0 );
+    PUT_UINT32_LE( X1, output,  4 );
+    PUT_UINT32_LE( X2, output,  8 );
+    PUT_UINT32_LE( X3, output, 12 );
+}
+#endif /* !MBEDTLS_AES_ENCRYPT_ALT */
+
+/*
+ * AES-ECB block decryption
+ */
+#if !defined(MBEDTLS_AES_DECRYPT_ALT)
+void mbedtls_aes_decrypt( mbedtls_aes_context *ctx,
+                          const unsigned char input[16],
+                          unsigned char output[16] )
+{
+    int i;
+    uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
+
+    RK = ctx->rk;
+
+    GET_UINT32_LE( X0, input,  0 ); X0 ^= *RK++;
+    GET_UINT32_LE( X1, input,  4 ); X1 ^= *RK++;
+    GET_UINT32_LE( X2, input,  8 ); X2 ^= *RK++;
+    GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++;
+
+    for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
+    {
+        AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
+        AES_RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
+    }
+
+    AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
+
+    X0 = *RK++ ^ \
+            ( (uint32_t) RSb[ ( Y0       ) & 0xFF ]       ) ^
+            ( (uint32_t) RSb[ ( Y3 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) RSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) RSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
+
+    X1 = *RK++ ^ \
+            ( (uint32_t) RSb[ ( Y1       ) & 0xFF ]       ) ^
+            ( (uint32_t) RSb[ ( Y0 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) RSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) RSb[ ( Y2 >> 24 ) & 0xFF ] << 24 );
+
+    X2 = *RK++ ^ \
+            ( (uint32_t) RSb[ ( Y2       ) & 0xFF ]       ) ^
+            ( (uint32_t) RSb[ ( Y1 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) RSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) RSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
+
+    X3 = *RK++ ^ \
+            ( (uint32_t) RSb[ ( Y3       ) & 0xFF ]       ) ^
+            ( (uint32_t) RSb[ ( Y2 >>  8 ) & 0xFF ] <<  8 ) ^
+            ( (uint32_t) RSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
+            ( (uint32_t) RSb[ ( Y0 >> 24 ) & 0xFF ] << 24 );
+
+    PUT_UINT32_LE( X0, output,  0 );
+    PUT_UINT32_LE( X1, output,  4 );
+    PUT_UINT32_LE( X2, output,  8 );
+    PUT_UINT32_LE( X3, output, 12 );
+}
+#endif /* !MBEDTLS_AES_DECRYPT_ALT */
+
 /*
  * AES-ECB block encryption/decryption
  */
@@ -711,9 +829,6 @@ int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
                     const unsigned char input[16],
                     unsigned char output[16] )
 {
-    int i;
-    uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
-
 #if defined(MBEDTLS_AESNI_C) && defined(MBEDTLS_HAVE_X86_64)
     if( mbedtls_aesni_supports( MBEDTLS_AESNI_AES ) )
         return( mbedtls_aesni_crypt_ecb( ctx, mode, input, output ) );
@@ -731,86 +846,10 @@ int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
     }
 #endif
 
-    RK = ctx->rk;
+    if( mode == MBEDTLS_AES_ENCRYPT )
-
+        mbedtls_aes_encrypt( ctx, input, output );
-    GET_UINT32_LE( X0, input,  0 ); X0 ^= *RK++;
+    else
-    GET_UINT32_LE( X1, input,  4 ); X1 ^= *RK++;
+        mbedtls_aes_decrypt( ctx, input, output );
-    GET_UINT32_LE( X2, input,  8 ); X2 ^= *RK++;
-    GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++;
-
-    if( mode == MBEDTLS_AES_DECRYPT )
-    {
-        for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
-        {
-            AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
-            AES_RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
-        }
-
-        AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
-
-        X0 = *RK++ ^ \
-                ( (uint32_t) RSb[ ( Y0       ) & 0xFF ]       ) ^
-                ( (uint32_t) RSb[ ( Y3 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) RSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) RSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
-
-        X1 = *RK++ ^ \
-                ( (uint32_t) RSb[ ( Y1       ) & 0xFF ]       ) ^
-                ( (uint32_t) RSb[ ( Y0 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) RSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) RSb[ ( Y2 >> 24 ) & 0xFF ] << 24 );
-
-        X2 = *RK++ ^ \
-                ( (uint32_t) RSb[ ( Y2       ) & 0xFF ]       ) ^
-                ( (uint32_t) RSb[ ( Y1 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) RSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) RSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
-
-        X3 = *RK++ ^ \
-                ( (uint32_t) RSb[ ( Y3       ) & 0xFF ]       ) ^
-                ( (uint32_t) RSb[ ( Y2 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) RSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) RSb[ ( Y0 >> 24 ) & 0xFF ] << 24 );
-    }
-    else /* MBEDTLS_AES_ENCRYPT */
-    {
-        for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
-        {
-            AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
-            AES_FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
-        }
-
-        AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
-
-        X0 = *RK++ ^ \
-                ( (uint32_t) FSb[ ( Y0       ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( Y1 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
-
-        X1 = *RK++ ^ \
-                ( (uint32_t) FSb[ ( Y1       ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( Y2 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( Y0 >> 24 ) & 0xFF ] << 24 );
-
-        X2 = *RK++ ^ \
-                ( (uint32_t) FSb[ ( Y2       ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( Y3 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
-
-        X3 = *RK++ ^ \
-                ( (uint32_t) FSb[ ( Y3       ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( Y0 >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( Y2 >> 24 ) & 0xFF ] << 24 );
-    }
-
-    PUT_UINT32_LE( X0, output,  0 );
-    PUT_UINT32_LE( X1, output,  4 );
-    PUT_UINT32_LE( X2, output,  8 );
-    PUT_UINT32_LE( X3, output, 12 );
 
     return( 0 );
 }