Merge pull request #4297 from gilles-peskine-arm/ecp-add-fix-202104

Fix ECP arithmetic bug and read of zero-padded negative number

library/bignum.c

@@ -470,6 +470,7 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t i, j, slen, n;
+    int sign = 1;
     mbedtls_mpi_uint d;
     mbedtls_mpi T;
     MPI_VALIDATE_RET( X != NULL );
@@ -480,6 +481,12 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
 
     mbedtls_mpi_init( &T );
 
+    if( s[0] == '-' )
+    {
+        ++s;
+        sign = -1;
+    }
+
     slen = strlen( s );
 
     if( radix == 16 )
@@ -494,12 +501,6 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
 
         for( i = slen, j = 0; i > 0; i--, j++ )
         {
-            if( i == 1 && s[i - 1] == '-' )
-            {
-                X->s = -1;
-                break;
-            }
-
             MBEDTLS_MPI_CHK( mpi_get_digit( &d, radix, s[i - 1] ) );
             X->p[j / ( 2 * ciL )] |= d << ( ( j % ( 2 * ciL ) ) << 2 );
         }
@@ -510,26 +511,15 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
 
         for( i = 0; i < slen; i++ )
         {
-            if( i == 0 && s[i] == '-' )
-            {
-                X->s = -1;
-                continue;
-            }
-
             MBEDTLS_MPI_CHK( mpi_get_digit( &d, radix, s[i] ) );
             MBEDTLS_MPI_CHK( mbedtls_mpi_mul_int( &T, X, radix ) );
-
+            MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( X, &T, d ) );
-            if( X->s == 1 )
-            {
-                MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( X, &T, d ) );
-            }
-            else
-            {
-                MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( X, &T, d ) );
-            }
         }
     }
 
+    if( sign < 0 && mbedtls_mpi_bitlen( X ) != 0 )
+        X->s = -1;
+
 cleanup:
 
     mbedtls_mpi_free( &T );

library/ecp.c

@@ -77,6 +77,8 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
 
+#include "ecp_invasive.h"
+
 #include <string.h>
 
 #if !defined(MBEDTLS_ECP_ALT)

library/ecp_curves.c

@@ -25,6 +25,8 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
 
+#include "ecp_invasive.h"
+
 #include <string.h>
 
 #if !defined(MBEDTLS_ECP_ALT)
@@ -1028,26 +1030,35 @@ static inline void sub32( uint32_t *dst, uint32_t src, signed char *carry )
     STORE32; i++;                               \
     cur = c > 0 ? c : 0; STORE32;               \
     cur = 0; while( ++i < MAX32 ) { STORE32; }  \
-    if( c < 0 ) fix_negative( N, c, bits );
+    if( c < 0 ) mbedtls_ecp_fix_negative( N, c, bits );
 
 /*
  * If the result is negative, we get it in the form
- * c * 2^(bits + 32) + N, with c negative and N positive shorter than 'bits'
+ * c * 2^bits + N, with c negative and N positive shorter than 'bits'
  */
-static inline void fix_negative( mbedtls_mpi *N, signed char c, size_t bits )
+MBEDTLS_STATIC_TESTABLE
+void mbedtls_ecp_fix_negative( mbedtls_mpi *N, signed char c, size_t bits )
 {
     size_t i;
 
-    /* Set N := N - 2^bits */
+    /* Set N := 2^bits - 1 - N. We know that 0 <= N < 2^bits, so
-    --N->p[0];
+     * set the absolute value to 0xfff...fff - N. There is no carry
+     * since we're subtracting from all-bits-one.  */
     for( i = 0; i <= bits / 8 / sizeof( mbedtls_mpi_uint ); i++ )
     {
         N->p[i] = ~(mbedtls_mpi_uint)0 - N->p[i];
     }
+    /* Add 1, taking care of the carry. */
+    i = 0;
+    do
+        ++N->p[i];
+    while( N->p[i++] == 0 && i <= bits / 8 / sizeof( mbedtls_mpi_uint ) );
+    /* Invert the sign.
+     * Now N = N0 - 2^bits where N0 is the initial value of N. */
     N->s = -1;
 
-    /* Add |c| * 2^(bits + 32) to the absolute value. Since c and N are
+    /* Add |c| * 2^bits to the absolute value. Since c and N are
-    * negative, this adds c * 2^(bits + 32). */
+    * negative, this adds c * 2^bits. */
     mbedtls_mpi_uint msw = (mbedtls_mpi_uint) -c;
 #if defined(MBEDTLS_HAVE_INT64)
     if( bits == 224 )

library/ecp_invasive.h

@@ -0,0 +1,51 @@
+/**
+ * \file ecp_invasive.h
+ *
+ * \brief ECP module: interfaces for invasive testing only.
+ *
+ * The interfaces in this file are intended for testing purposes only.
+ * They SHOULD NOT be made available in library integrations except when
+ * building the library for testing.
+ */
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+#ifndef MBEDTLS_ECP_INVASIVE_H
+#define MBEDTLS_ECP_INVASIVE_H
+
+#include "common.h"
+#include "mbedtls/ecp.h"
+
+#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_ECP_C)
+
+#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) ||   \
+    defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
+/* Preconditions:
+ *   - bits is a multiple of 64 or is 224
+ *   - c is -1 or -2
+ *   - 0 <= N < 2^bits
+ *   - N has room for bits plus one limb
+ *
+ * Behavior:
+ * Set N to c * 2^bits + old_value_of_N.
+ */
+void mbedtls_ecp_fix_negative( mbedtls_mpi *N, signed char c, size_t bits );
+#endif
+
+#endif /* MBEDTLS_TEST_HOOKS && MBEDTLS_ECP_C */
+
+#endif /* MBEDTLS_ECP_INVASIVE_H */

tests/suites/test_suite_ecp.data

@@ -458,6 +458,14 @@ ECP point multiplication rng fail Curve25519
 depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
 ecp_test_mul_rng:MBEDTLS_ECP_DP_CURVE25519:"5AC99F33632E5A768DE7E81BF854C27C46E3FBF2ABBACD29EC4AFF517369C660"
 
+ECP point muladd secp256r1 #1
+depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+ecp_muladd:MBEDTLS_ECP_DP_SECP256R1:"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e0e1ff20e1ffe120e1e1e173287170a761308491683e345cacaebb500c96e1a7bbd37772968b2c951f0579":"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1ffffffff20e120e1e1e1e13a4e135157317b79d4ecf329fed4f9eb00dc67dbddae33faca8b6d8a0255b5ce":"04fab65e09aa5dd948320f86246be1d3fc571e7f799d9005170ed5cc868b67598431a668f96aa9fd0b0eb15f0edf4c7fe1be2885eadcb57e3db4fdd093585d3fa6"
+
+ECP point muladd secp256r1 #2
+depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+ecp_muladd:MBEDTLS_ECP_DP_SECP256R1:"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1ffffffff20e120e1e1e1e13a4e135157317b79d4ecf329fed4f9eb00dc67dbddae33faca8b6d8a0255b5ce":"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e0e1ff20e1ffe120e1e1e173287170a761308491683e345cacaebb500c96e1a7bbd37772968b2c951f0579":"04fab65e09aa5dd948320f86246be1d3fc571e7f799d9005170ed5cc868b67598431a668f96aa9fd0b0eb15f0edf4c7fe1be2885eadcb57e3db4fdd093585d3fa6"
+
 ECP test vectors Curve448 (RFC 7748 6.2, after decodeUCoordinate)
 depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
 ecp_test_vec_x:MBEDTLS_ECP_DP_CURVE448:"eb7298a5c0d8c29a1dab27f1a6826300917389449741a974f5bac9d98dc298d46555bce8bae89eeed400584bb046cf75579f51d125498f98":"a01fc432e5807f17530d1288da125b0cd453d941726436c8bbd9c5222c3da7fa639ce03db8d23b274a0721a1aed5227de6e3b731ccf7089b":"ad997351b6106f36b0d1091b929c4c37213e0d2b97e85ebb20c127691d0dad8f1d8175b0723745e639a3cb7044290b99e0e2a0c27a6a301c":"0936f37bc6c1bd07ae3dec7ab5dc06a73ca13242fb343efc72b9d82730b445f3d4b0bd077162a46dcfec6f9b590bfcbcf520cdb029a8b73e":"9d874a5137509a449ad5853040241c5236395435c36424fd560b0cb62b281d285275a740ce32a22dd1740f4aa9161cec95ccc61a18f4ff07"
@@ -508,3 +516,127 @@ ecp_muladd_restart:MBEDTLS_ECP_DP_SECP256R1:"CB28E0999B9C7715FD0A80D8E47A7707971
 ECP restartable muladd secp256r1 max_ops=250
 depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
 ecp_muladd_restart:MBEDTLS_ECP_DP_SECP256R1:"CB28E0999B9C7715FD0A80D8E47A77079716CBBF917DD72E97566EA1C066957C":"2B57C0235FB7489768D058FF4911C20FDBE71E3699D91339AFBB903EE17255DC":"C3875E57C85038A0D60370A87505200DC8317C8C534948BEA6559C7C18E6D4CE":"3B4E49C4FDBFC006FF993C81A50EAE221149076D6EC09DDD9FB3B787F85B6483":"2442A5CC0ECD015FA3CA31DC8E2BBC70BF42D60CBCA20085E0822CB04235E970":"6FC98BD7E50211A4A27102FA3549DF79EBCB4BF246B80945CDDFE7D509BBFD7D":250:4:64
+
+ECP fix_negative: 0, -1, 224
+fix_negative:"00":-1:224
+
+ECP fix_negative: 1, -1, 224
+fix_negative:"01":-1:224
+
+ECP fix_negative: 2^32-1, -1, 224
+fix_negative:"ffffffff":-1:224
+
+ECP fix_negative: 2^32, -1, 224
+fix_negative:"0100000000":-1:224
+
+ECP fix_negative: 2^64-1, -1, 224
+fix_negative:"ffffffffffffffff":-1:224
+
+ECP fix_negative: 2^64, -1, 224
+fix_negative:"010000000000000000":-1:224
+
+ECP fix_negative: 2^128-1, -1, 224
+fix_negative:"ffffffffffffffffffffffffffffffff":-1:224
+
+ECP fix_negative: 2^128, -1, 224
+fix_negative:"0100000000000000000000000000000000":-1:224
+
+ECP fix_negative: 2^128+1, -1, 224
+fix_negative:"0100000000000000000000000000000001":-1:224
+
+ECP fix_negative: 2^224-1, -1, 224
+fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-1:224
+
+ECP fix_negative: 0, -2, 224
+fix_negative:"00":-2:224
+
+ECP fix_negative: 1, -2, 224
+fix_negative:"01":-2:224
+
+ECP fix_negative: 2^32-1, -2, 224
+fix_negative:"ffffffff":-2:224
+
+ECP fix_negative: 2^32, -2, 224
+fix_negative:"0100000000":-2:224
+
+ECP fix_negative: 2^64-1, -2, 224
+fix_negative:"ffffffffffffffff":-2:224
+
+ECP fix_negative: 2^64, -2, 224
+fix_negative:"010000000000000000":-2:224
+
+ECP fix_negative: 2^128-1, -2, 224
+fix_negative:"ffffffffffffffffffffffffffffffff":-2:224
+
+ECP fix_negative: 2^128, -2, 224
+fix_negative:"0100000000000000000000000000000000":-2:224
+
+ECP fix_negative: 2^128+1, -2, 224
+fix_negative:"0100000000000000000000000000000001":-2:224
+
+ECP fix_negative: 2^224-1, -2, 224
+fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-2:224
+
+ECP fix_negative: 0, -1, 256
+fix_negative:"00":-1:256
+
+ECP fix_negative: 1, -1, 256
+fix_negative:"01":-1:256
+
+ECP fix_negative: 2^32-1, -1, 256
+fix_negative:"ffffffff":-1:256
+
+ECP fix_negative: 2^32, -1, 256
+fix_negative:"0100000000":-1:256
+
+ECP fix_negative: 2^64-1, -1, 256
+fix_negative:"ffffffffffffffff":-1:256
+
+ECP fix_negative: 2^64, -1, 256
+fix_negative:"010000000000000000":-1:256
+
+ECP fix_negative: 2^128-1, -1, 256
+fix_negative:"ffffffffffffffffffffffffffffffff":-1:256
+
+ECP fix_negative: 2^128, -1, 256
+fix_negative:"0100000000000000000000000000000000":-1:256
+
+ECP fix_negative: 2^128+1, -1, 256
+fix_negative:"0100000000000000000000000000000001":-1:256
+
+ECP fix_negative: 2^256-1, -1, 256
+fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-1:256
+
+ECP fix_negative: 0, -2, 256
+fix_negative:"00":-2:256
+
+ECP fix_negative: 1, -2, 256
+fix_negative:"01":-2:256
+
+ECP fix_negative: 2^32-1, -2, 256
+fix_negative:"ffffffff":-2:256
+
+ECP fix_negative: 2^32, -2, 256
+fix_negative:"0100000000":-2:256
+
+ECP fix_negative: 2^64-1, -2, 256
+fix_negative:"ffffffffffffffff":-2:256
+
+ECP fix_negative: 2^64, -2, 256
+fix_negative:"010000000000000000":-2:256
+
+ECP fix_negative: 2^128-1, -2, 256
+fix_negative:"ffffffffffffffffffffffffffffffff":-2:256
+
+ECP fix_negative: 2^128, -2, 256
+fix_negative:"0100000000000000000000000000000000":-2:256
+
+ECP fix_negative: 2^128+1, -2, 256
+fix_negative:"0100000000000000000000000000000001":-2:256
+
+ECP fix_negative: 2^256-1, -2, 256
+fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-2:256
+
+# The first call to fix_negative in the test case of issue #4296.
+ECP fix_negative: #4296.1
+fix_negative:"8A4DD4C8B42C5EAED15FE4F4579F4CE513EC90A94010BF000000000000000000":-1:256

tests/suites/test_suite_ecp.function

@@ -1,6 +1,15 @@
 /* BEGIN_HEADER */
 #include "mbedtls/ecp.h"
 
+#include "ecp_invasive.h"
+
+#if defined(MBEDTLS_TEST_HOOKS) &&                  \
+    ( defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) ||  \
+      defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) ||  \
+      defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) )
+#define HAVE_FIX_NEGATIVE
+#endif
+
 #define ECP_PF_UNKNOWN     -1
 
 #define ECP_PT_RESET( x )           \
@@ -752,6 +761,52 @@ exit:
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
+void ecp_muladd( int id,
+                 data_t *u1_bin, data_t *P1_bin,
+                 data_t *u2_bin, data_t *P2_bin,
+                 data_t *expected_result )
+{
+    /* Compute R = u1 * P1 + u2 * P2 */
+    mbedtls_ecp_group grp;
+    mbedtls_ecp_point P1, P2, R;
+    mbedtls_mpi u1, u2;
+    uint8_t actual_result[MBEDTLS_ECP_MAX_PT_LEN];
+    size_t len;
+
+    mbedtls_ecp_group_init( &grp );
+    mbedtls_ecp_point_init( &P1 );
+    mbedtls_ecp_point_init( &P2 );
+    mbedtls_ecp_point_init( &R );
+    mbedtls_mpi_init( &u1 );
+    mbedtls_mpi_init( &u2 );
+
+    TEST_EQUAL( 0, mbedtls_ecp_group_load( &grp, id ) );
+    TEST_EQUAL( 0, mbedtls_mpi_read_binary( &u1, u1_bin->x, u1_bin->len ) );
+    TEST_EQUAL( 0, mbedtls_mpi_read_binary( &u2, u2_bin->x, u2_bin->len ) );
+    TEST_EQUAL( 0, mbedtls_ecp_point_read_binary( &grp, &P1,
+                                                  P1_bin->x, P1_bin->len ) );
+    TEST_EQUAL( 0, mbedtls_ecp_point_read_binary( &grp, &P2,
+                                                  P2_bin->x, P2_bin->len ) );
+
+    TEST_EQUAL( 0, mbedtls_ecp_muladd( &grp, &R, &u1, &P1, &u2, &P2 ) );
+    TEST_EQUAL( 0, mbedtls_ecp_point_write_binary(
+                    &grp, &R, MBEDTLS_ECP_PF_UNCOMPRESSED,
+                    &len, actual_result, sizeof( actual_result ) ) );
+
+    ASSERT_COMPARE( expected_result->x, expected_result->len,
+                    actual_result, len );
+
+exit:
+    mbedtls_ecp_group_free( &grp );
+    mbedtls_ecp_point_free( &P1 );
+    mbedtls_ecp_point_free( &P2 );
+    mbedtls_ecp_point_free( &R );
+    mbedtls_mpi_free( &u1 );
+    mbedtls_mpi_free( &u2 );
+}
+/* END_CASE */
+
 /* BEGIN_CASE */
 void ecp_fast_mod( int id, char * N_str )
 {
@@ -1152,6 +1207,36 @@ exit:
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:HAVE_FIX_NEGATIVE */
+void fix_negative( data_t *N_bin, int c, int bits )
+{
+    mbedtls_mpi C, M, N;
+
+    mbedtls_mpi_init( &C );
+    mbedtls_mpi_init( &M );
+    mbedtls_mpi_init( &N );
+
+    /* C = - c * 2^bits (positive since c is negative) */
+    TEST_EQUAL( 0, mbedtls_mpi_lset( &C, -c ) );
+    TEST_EQUAL( 0, mbedtls_mpi_shift_l( &C, bits ) );
+
+    TEST_EQUAL( 0, mbedtls_mpi_read_binary( &N, N_bin->x, N_bin->len ) );
+    TEST_EQUAL( 0, mbedtls_mpi_grow( &N, C.n ) );
+
+    /* M = N - C = - ( C - N ) (expected result of fix_negative) */
+    TEST_EQUAL( 0, mbedtls_mpi_sub_mpi( &M, &N, &C ) );
+
+    mbedtls_ecp_fix_negative( &N, c, bits );
+
+    TEST_EQUAL( 0, mbedtls_mpi_cmp_mpi( &N, &M ) );
+
+exit:
+    mbedtls_mpi_free( &C );
+    mbedtls_mpi_free( &M );
+    mbedtls_mpi_free( &N );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
 void ecp_selftest(  )
 {

tests/suites/test_suite_mpi.data

@@ -10,21 +10,39 @@ mpi_null:
 Base test mpi_read_write_string #1
 mpi_read_write_string:10:"128":10:"128":100:0:0
 
+Base test mpi_read_write_string #1 (Leading 0)
+mpi_read_write_string:10:"0128":10:"128":100:0:0
+
 Base test mpi_read_write_string #2
 mpi_read_write_string:10:"128":16:"80":100:0:0
 
-Base test mpi_read_write_string #3 (Read zero)
+Base test mpi_read_write_string #3 (Read zero decimal)
 mpi_read_write_string:10:"0":10:"0":100:0:0
 
-Base test mpi_read_write_string #3 (Negative decimal) [#1]
+Base test mpi_read_write_string #3 (Read zero hex)
+mpi_read_write_string:16:"0":16:"00":100:0:0
+
+Base test mpi_read_write_string #3 (Read minus zero decimal)
+mpi_read_write_string:10:"-0":10:"0":100:0:0
+
+Base test mpi_read_write_string #3 (Read minus zero hex)
+mpi_read_write_string:16:"-0":16:"00":100:0:0
+
+Base test mpi_read_write_string #3 (Negative decimal)
 mpi_read_write_string:10:"-23":10:"-23":100:0:0
 
-Base test mpi_read_write_string #3 (Negative hex)
+Base test mpi_read_write_string #3 (Negative decimal, leading 0)
+mpi_read_write_string:10:"-023":10:"-23":100:0:0
+
+Base test mpi_read_write_string #3 (Negative hex -> decimal)
 mpi_read_write_string:16:"-20":10:"-32":100:0:0
 
-Base test mpi_read_write_string #3 (Negative decimal) [#2]
+Base test mpi_read_write_string #3 (Negative hex)
 mpi_read_write_string:16:"-23":16:"-23":100:0:0
 
+Base test mpi_read_write_string #3 (Negative hex, leading 0)
+mpi_read_write_string:16:"-023":16:"-23":100:0:0
+
 Base test mpi_read_write_string #4 (Buffer just fits)
 mpi_read_write_string:16:"-4":4:"-10":4:0:0
 
@@ -49,12 +67,18 @@ mpi_read_write_string:10:"29":15:"1e":100:0:0
 Test mpi_read_write_string #7
 mpi_read_write_string:10:"56125680981752282334141896320372489490613963693556392520816017892111350604111697682705498319512049040516698827829292076808006940873974979584527073481012636016353913462376755556720019831187364993587901952757307830896531678727717924":16:"0941379d00fed1491fe15df284dfde4a142f68aa8d412023195cee66883e6290ffe703f4ea5963bf212713cee46b107c09182b5edcd955adac418bf4918e2889af48e1099d513830cec85c26ac1e158b52620e33ba8692f893efbb2f958b4424":200:0:0
 
-Test mpi_read_write_string #8 (Empty MPI -> hex)
+Test mpi_read_write_string #8 (Empty MPI hex -> hex)
 mpi_read_write_string:16:"":16:"00":4:0:0
 
-Test mpi_read_write_string #9 (Empty MPI -> dec)
+Test mpi_read_write_string #9 (Empty MPI hex -> dec)
 mpi_read_write_string:16:"":10:"0":4:0:0
 
+Test mpi_read_write_string #8 (Empty MPI dec -> hex)
+mpi_read_write_string:10:"":16:"00":4:0:0
+
+Test mpi_read_write_string #9 (Empty MPI dec -> dec)
+mpi_read_write_string:10:"":10:"0":4:0:0
+
 Test mpi_write_string #10 (Negative hex with odd number of digits)
 mpi_read_write_string:16:"-1":16:"":3:0:MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL
 

visualc/VS2010/mbedTLS.vcxproj

@@ -250,6 +250,7 @@
     <ClInclude Include="..\..\tests\include\test\drivers\test_driver.h" />
     <ClInclude Include="..\..\library\check_crypto_config.h" />
     <ClInclude Include="..\..\library\common.h" />
+    <ClInclude Include="..\..\library\ecp_invasive.h" />
     <ClInclude Include="..\..\library\mps_common.h" />
     <ClInclude Include="..\..\library\mps_error.h" />
     <ClInclude Include="..\..\library\mps_reader.h" />