Merge pull request #6621 from ronald-cron-arm/tls13-early-data-write
TLS 1.3: Add definition of mbedtls_ssl_{write,read}_early_datadiff --git a/library/bignum.c b/library/bignum.c
index ba03988..a68957a 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -968,17 +968,15 @@
carry = mbedtls_mpi_core_sub( X->p, A->p, B->p, n );
if( carry != 0 )
{
- /* Propagate the carry to the first nonzero limb of X. */
- for( ; n < X->n && X->p[n] == 0; n++ )
- --X->p[n];
- /* If we ran out of space for the carry, it means that the result
- * is negative. */
- if( n == X->n )
+ /* Propagate the carry through the rest of X. */
+ carry = mbedtls_mpi_core_sub_int( X->p + n, X->p + n, carry, X->n - n );
+
+ /* If we have further carry/borrow, the result is negative. */
+ if( carry != 0 )
{
ret = MBEDTLS_ERR_MPI_NEGATIVE_VALUE;
goto cleanup;
}
- --X->p[n];
}
/* X should always be positive as a result of unsigned subtractions. */
diff --git a/library/bignum_core.c b/library/bignum_core.c
index 34aecda..41d3239 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -590,6 +590,22 @@
/* BEGIN MERGE SLOT 3 */
+mbedtls_mpi_uint mbedtls_mpi_core_sub_int( mbedtls_mpi_uint *X,
+ const mbedtls_mpi_uint *A,
+ mbedtls_mpi_uint c, /* doubles as carry */
+ size_t limbs )
+{
+ for( size_t i = 0; i < limbs; i++ )
+ {
+ mbedtls_mpi_uint s = A[i];
+ mbedtls_mpi_uint t = s - c;
+ c = ( t > s );
+ X[i] = t;
+ }
+
+ return( c );
+}
+
/* END MERGE SLOT 3 */
/* BEGIN MERGE SLOT 4 */
diff --git a/library/bignum_core.h b/library/bignum_core.h
index ad04e08..d48e705 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -504,6 +504,23 @@
/* BEGIN MERGE SLOT 3 */
+/**
+ * \brief Subtract unsigned integer from known-size large unsigned integers.
+ * Return the borrow.
+ *
+ * \param[out] X The result of the subtraction.
+ * \param[in] A The left operand.
+ * \param b The unsigned scalar to subtract.
+ * \param limbs Number of limbs of \p X and \p A.
+ *
+ * \return 1 if `A < b`.
+ * 0 if `A >= b`.
+ */
+mbedtls_mpi_uint mbedtls_mpi_core_sub_int( mbedtls_mpi_uint *X,
+ const mbedtls_mpi_uint *A,
+ mbedtls_mpi_uint b,
+ size_t limbs );
+
/* END MERGE SLOT 3 */
/* BEGIN MERGE SLOT 4 */
diff --git a/scripts/mbedtls_dev/bignum_core.py b/scripts/mbedtls_dev/bignum_core.py
index 4910dae..b8e2a31 100644
--- a/scripts/mbedtls_dev/bignum_core.py
+++ b/scripts/mbedtls_dev/bignum_core.py
@@ -763,6 +763,37 @@
# BEGIN MERGE SLOT 3
+class BignumCoreSubInt(BignumCoreTarget, bignum_common.OperationCommon):
+ """Test cases for bignum core sub int."""
+ count = 0
+ symbol = "-"
+ test_function = "mpi_core_sub_int"
+ test_name = "mpi_core_sub_int"
+ input_style = "arch_split"
+
+ @property
+ def is_valid(self) -> bool:
+ # This is "sub int", so b is only one limb
+ if bignum_common.limbs_mpi(self.int_b, self.bits_in_limb) > 1:
+ return False
+ return True
+
+ # Overriding because we don't want leading zeros on b
+ @property
+ def arg_b(self) -> str:
+ return self.val_b
+
+ def result(self) -> List[str]:
+ result = self.int_a - self.int_b
+
+ borrow, result = divmod(result, self.limb_boundary)
+
+ # Borrow will be -1 if non-zero, but we want it to be 1 in the test data
+ return [
+ self.format_result(result),
+ str(-borrow)
+ ]
+
# END MERGE SLOT 3
# BEGIN MERGE SLOT 4
diff --git a/tests/suites/test_suite_bignum_core.function b/tests/suites/test_suite_bignum_core.function
index 612a7c6..d5bb420 100644
--- a/tests/suites/test_suite_bignum_core.function
+++ b/tests/suites/test_suite_bignum_core.function
@@ -1049,6 +1049,52 @@
/* BEGIN MERGE SLOT 3 */
+/* BEGIN_CASE */
+void mpi_core_sub_int( char * input_A, char * input_B,
+ char * input_X, int borrow )
+{
+ /* We are testing A - b, where A is an MPI and b is a scalar, expecting
+ * result X with borrow borrow. However, for ease of handling we encode b
+ * as a 1-limb MPI (B) in the .data file. */
+
+ mbedtls_mpi_uint *A = NULL;
+ mbedtls_mpi_uint *B = NULL;
+ mbedtls_mpi_uint *X = NULL;
+ mbedtls_mpi_uint *R = NULL;
+ size_t A_limbs, B_limbs, X_limbs;
+
+ TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &A, &A_limbs, input_A ) );
+ TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &B, &B_limbs, input_B ) );
+ TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &X, &X_limbs, input_X ) );
+
+ /* The MPI encoding of scalar b must be only 1 limb */
+ TEST_EQUAL( B_limbs, 1 );
+
+ /* The subtraction is fixed-width, so A and X must have the same number of limbs */
+ TEST_EQUAL( A_limbs, X_limbs );
+ size_t limbs = A_limbs;
+
+ ASSERT_ALLOC( R, limbs );
+
+#define TEST_COMPARE_CORE_MPIS( A, B, limbs ) \
+ ASSERT_COMPARE( A, (limbs) * sizeof(mbedtls_mpi_uint), B, (limbs) * sizeof(mbedtls_mpi_uint) )
+
+ /* 1. R = A - b. Result and borrow should be correct */
+ TEST_EQUAL( mbedtls_mpi_core_sub_int( R, A, B[0], limbs ), borrow );
+ TEST_COMPARE_CORE_MPIS( R, X, limbs );
+
+ /* 2. A = A - b. Result and borrow should be correct */
+ TEST_EQUAL( mbedtls_mpi_core_sub_int( A, A, B[0], limbs ), borrow );
+ TEST_COMPARE_CORE_MPIS( A, X, limbs );
+
+exit:
+ mbedtls_free( A );
+ mbedtls_free( B );
+ mbedtls_free( X );
+ mbedtls_free( R );
+}
+/* END_CASE */
+
/* END MERGE SLOT 3 */
/* BEGIN MERGE SLOT 4 */