Add bignum_new.c starting with MPI_CORE(montmul) for Montgomery multiplication
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index ad0e599..cfa5e46 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -2016,6 +2016,7 @@
* library/bignum_core.c
* library/bignum_mod.c
* library/bignum_mod_raw.c
+ * library/bignum_new.c
* Caller: library/dhm.c
* library/ecp.c
* library/ecdsa.c
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 378cfb4..7e28df0 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -21,6 +21,7 @@
bignum_core.c
bignum_mod.c
bignum_mod_raw.c
+ bignum_new.c
camellia.c
ccm.c
chacha20.c
diff --git a/library/Makefile b/library/Makefile
index 85cea6b..041b5af 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -86,6 +86,7 @@
bignum_core.o \
bignum_mod.o \
bignum_mod_raw.o \
+ bignum_new.o \
camellia.o \
ccm.o \
chacha20.o \
diff --git a/library/bignum_core.h b/library/bignum_core.h
index 1e159a7..62d0151 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -172,8 +172,107 @@
*
* \return c The carry at the end of the operation.
*/
-mbedtls_mpi_uint mbedtls_mpi_core_mla( mbedtls_mpi_uint *d, size_t d_len ,
+mbedtls_mpi_uint mbedtls_mpi_core_mla( mbedtls_mpi_uint *d, size_t d_len,
const mbedtls_mpi_uint *s, size_t s_len,
mbedtls_mpi_uint b );
+#define MPI_CORE(func) mbedtls_mpi_core_ ## func ## _minimal
+
+/** Montgomery multiplication: X = A * B * R^-1 mod N (HAC 14.36)
+ *
+ * \param[out] X The destination MPI, as a big endian array of length \p n.
+ * On successful completion, X contains the result of
+ * the multiplication A * B * R^-1 mod N where
+ * R = (2^ciL)^n.
+ * \param[in] A Big endian presentation of first operand.
+ * Must have exactly \p n limbs.
+ * \param[in] B Big endian presentation of second operand.
+ * \param[in] B_len The number of limbs in \p B.
+ * \param[in] N Big endian presentation of the modulus.
+ * This must be odd and have exactly \p n limbs.
+ * \param[in] n The number of limbs in \p X, \p A, \p N.
+ * \param mm The Montgomery constant for \p N: -N^-1 mod 2^ciL.
+ * This can be calculated by `mpi_montg_init()`.
+ * \param[in,out] T Temporary storage of size at least 2*n+1 limbs.
+ * Its initial content is unused and
+ * its final content is indeterminate.
+ */
+void MPI_CORE(montmul)( mbedtls_mpi_uint *X,
+ const mbedtls_mpi_uint *A,
+ const mbedtls_mpi_uint *B, size_t B_len,
+ const mbedtls_mpi_uint *N, size_t n,
+ mbedtls_mpi_uint mm, mbedtls_mpi_uint *T );
+
+/**
+ * \brief Perform a known-size multiply accumulate operation
+ *
+ * Add \p b * \p s to \p d.
+ *
+ * \param[in,out] d The pointer to the (little-endian) array
+ * representing the bignum to accumulate onto.
+ * \param d_len The number of limbs of \p d. This must be
+ * at least \p s_len.
+ * \param[in] s The pointer to the (little-endian) array
+ * representing the bignum to multiply with.
+ * This may be the same as \p d. Otherwise,
+ * it must be disjoint from \p d.
+ * \param s_len The number of limbs of \p s.
+ * \param b A scalar to multiply with.
+ *
+ * \return c The carry at the end of the operation.
+ */
+mbedtls_mpi_uint MPI_CORE(mla)( mbedtls_mpi_uint *d, size_t d_len ,
+ const mbedtls_mpi_uint *s, size_t s_len,
+ mbedtls_mpi_uint b );
+
+/**
+ * \brief Subtract two known-size large unsigned integers, returning the borrow.
+ *
+ * Calculate l - r where l and r have the same size.
+ * This function operates modulo (2^ciL)^n and returns the carry
+ * (1 if there was a wraparound, i.e. if `l < r`, and 0 otherwise).
+ *
+ * d may be aliased to l or r.
+ *
+ * \param[out] d The result of the subtraction.
+ * \param[in] l The left operand.
+ * \param[in] r The right operand.
+ * \param n Number of limbs of \p d, \p l and \p r.
+ *
+ * \return 1 if `l < r`.
+ * 0 if `l >= r`.
+ */
+mbedtls_mpi_uint MPI_CORE(sub)( mbedtls_mpi_uint *d,
+ const mbedtls_mpi_uint *l,
+ const mbedtls_mpi_uint *r,
+ size_t n );
+
+/**
+ * \brief Constant-time conditional addition of two known-size large unsigned
+ * integers, returning the carry.
+ *
+ * Functionally equivalent to
+ *
+ * ```
+ * if( cond )
+ * d += r;
+ * return carry;
+ * ```
+ *
+ * \param[in,out] d The pointer to the (little-endian) array
+ * representing the bignum to accumulate onto.
+ * \param[in] r The pointer to the (little-endian) array
+ * representing the bignum to conditionally add
+ * to \p d. This must be disjoint from \p d.
+ * \param n Number of limbs of \p d and \p r.
+ * \param cond Condition bit dictating whether addition should
+ * happen or not. This must be \c 0 or \c 1.
+ *
+ * \return 1 if `d + cond*r >= (2^{ciL})^n`, 0 otherwise.
+ */
+mbedtls_mpi_uint MPI_CORE(add_if)( mbedtls_mpi_uint *d,
+ const mbedtls_mpi_uint *r,
+ size_t n,
+ unsigned cond );
+
#endif /* MBEDTLS_BIGNUM_CORE_H */
diff --git a/library/bignum_new.c b/library/bignum_new.c
new file mode 100644
index 0000000..29c1212
--- /dev/null
+++ b/library/bignum_new.c
@@ -0,0 +1,126 @@
+/*
+ * Multi-precision integer library
+ *
+ * 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.
+ */
+
+#include "common.h"
+
+#if defined(MBEDTLS_BIGNUM_C)
+
+#include "mbedtls/bignum.h"
+#include "bignum_core.h"
+#include "bn_mul.h"
+
+#include <string.h>
+
+void MPI_CORE(montmul)( mbedtls_mpi_uint *X,
+ const mbedtls_mpi_uint *A,
+ const mbedtls_mpi_uint *B,
+ size_t B_len,
+ const mbedtls_mpi_uint *N,
+ size_t n,
+ mbedtls_mpi_uint mm,
+ mbedtls_mpi_uint *T )
+{
+ memset( T, 0, (2*n+1)*ciL );
+
+ for( size_t i = 0; i < n; i++, T++ )
+ {
+ mbedtls_mpi_uint u0, u1;
+ /* T = (T + u0*B + u1*N) / 2^biL */
+ u0 = A[i];
+ u1 = ( T[0] + u0 * B[0] ) * mm;
+
+ (void) MPI_CORE(mla)( T, n + 2, B, B_len, u0 );
+ (void) MPI_CORE(mla)( T, n + 2, N, n, u1 );
+ }
+
+ mbedtls_mpi_uint carry, borrow, fixup;
+
+ carry = T[n];
+ borrow = MPI_CORE(sub)( X, T, N, n );
+ fixup = carry < borrow;
+ (void) MPI_CORE(add_if)( X, N, n, fixup );
+}
+
+mbedtls_mpi_uint MPI_CORE(mla)( mbedtls_mpi_uint *d, size_t d_len,
+ const mbedtls_mpi_uint *s, size_t s_len,
+ mbedtls_mpi_uint b )
+{
+ mbedtls_mpi_uint c = 0; /* carry */
+ if( d_len < s_len )
+ s_len = d_len;
+ size_t excess_len = d_len - s_len;
+ size_t steps_x8 = s_len / 8;
+ size_t steps_x1 = s_len & 7;
+
+ while( steps_x8-- )
+ {
+ MULADDC_X8_INIT
+ MULADDC_X8_CORE
+ MULADDC_X8_STOP
+ }
+
+ while( steps_x1-- )
+ {
+ MULADDC_X1_INIT
+ MULADDC_X1_CORE
+ MULADDC_X1_STOP
+ }
+
+ while( excess_len-- )
+ {
+ *d += c; c = ( *d < c ); d++;
+ }
+
+ return( c );
+}
+
+mbedtls_mpi_uint MPI_CORE(sub)( mbedtls_mpi_uint *d,
+ const mbedtls_mpi_uint *l,
+ const mbedtls_mpi_uint *r,
+ size_t n )
+{
+ mbedtls_mpi_uint c = 0, t, z;
+
+ for( size_t i = 0; i < n; i++ )
+ {
+ z = ( l[i] < c ); t = l[i] - c;
+ c = ( t < r[i] ) + z; d[i] = t - r[i];
+ }
+
+ return( c );
+}
+
+mbedtls_mpi_uint MPI_CORE(add_if)( mbedtls_mpi_uint *d,
+ const mbedtls_mpi_uint *r,
+ size_t n,
+ unsigned cond )
+{
+ mbedtls_mpi_uint c = 0, t;
+ for( size_t i = 0; i < n; i++ )
+ {
+ mbedtls_mpi_uint add = cond * r[i];
+ t = c;
+ t += d[i]; c = ( t < d[i] );
+ t += add; c += ( t < add );
+ d[i] = t;
+ }
+ return( c );
+}
+
+#endif /* MBEDTLS_BIGNUM_C */