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https://github.com/Mbed-TLS/mbedtls.git
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Add bignum_new.c starting with MPI_CORE(montmul) for Montgomery multiplication
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
This commit is contained in:
Hanno Becker
Tom Cosgrove
parent
82d3f1e824
commit
71f4b0dda6
@ -2016,6 +2016,7 @@
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* library/bignum_core.c
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* library/bignum_mod.c
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* library/bignum_mod_raw.c
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* library/bignum_new.c
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* Caller: library/dhm.c
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* library/ecp.c
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* library/ecdsa.c
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@ -21,6 +21,7 @@ set(src_crypto
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bignum_core.c
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bignum_mod.c
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bignum_mod_raw.c
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bignum_new.c
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camellia.c
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ccm.c
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chacha20.c
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@ -86,6 +86,7 @@ OBJS_CRYPTO= \
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bignum_core.o \
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bignum_mod.o \
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bignum_mod_raw.o \
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bignum_new.o \
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camellia.o \
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ccm.o \
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chacha20.o \
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@ -172,8 +172,107 @@ int mbedtls_mpi_core_write_be( const mbedtls_mpi_uint *A,
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*
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* \return c The carry at the end of the operation.
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*/
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mbedtls_mpi_uint mbedtls_mpi_core_mla( mbedtls_mpi_uint *d, size_t d_len ,
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mbedtls_mpi_uint mbedtls_mpi_core_mla( mbedtls_mpi_uint *d, size_t d_len,
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const mbedtls_mpi_uint *s, size_t s_len,
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mbedtls_mpi_uint b );
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#define MPI_CORE(func) mbedtls_mpi_core_ ## func ## _minimal
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/** Montgomery multiplication: X = A * B * R^-1 mod N (HAC 14.36)
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*
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* \param[out] X The destination MPI, as a big endian array of length \p n.
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* On successful completion, X contains the result of
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* the multiplication A * B * R^-1 mod N where
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* R = (2^ciL)^n.
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* \param[in] A Big endian presentation of first operand.
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* Must have exactly \p n limbs.
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* \param[in] B Big endian presentation of second operand.
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* \param[in] B_len The number of limbs in \p B.
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* \param[in] N Big endian presentation of the modulus.
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* This must be odd and have exactly \p n limbs.
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* \param[in] n The number of limbs in \p X, \p A, \p N.
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* \param mm The Montgomery constant for \p N: -N^-1 mod 2^ciL.
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* This can be calculated by `mpi_montg_init()`.
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* \param[in,out] T Temporary storage of size at least 2*n+1 limbs.
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* Its initial content is unused and
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* its final content is indeterminate.
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*/
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void MPI_CORE(montmul)( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_uint *B, size_t B_len,
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const mbedtls_mpi_uint *N, size_t n,
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mbedtls_mpi_uint mm, mbedtls_mpi_uint *T );
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/**
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* \brief Perform a known-size multiply accumulate operation
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*
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* Add \p b * \p s to \p d.
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*
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* \param[in,out] d The pointer to the (little-endian) array
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* representing the bignum to accumulate onto.
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* \param d_len The number of limbs of \p d. This must be
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* at least \p s_len.
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* \param[in] s The pointer to the (little-endian) array
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* representing the bignum to multiply with.
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* This may be the same as \p d. Otherwise,
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* it must be disjoint from \p d.
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* \param s_len The number of limbs of \p s.
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* \param b A scalar to multiply with.
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*
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* \return c The carry at the end of the operation.
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*/
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mbedtls_mpi_uint MPI_CORE(mla)( mbedtls_mpi_uint *d, size_t d_len ,
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const mbedtls_mpi_uint *s, size_t s_len,
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mbedtls_mpi_uint b );
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/**
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* \brief Subtract two known-size large unsigned integers, returning the borrow.
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*
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* Calculate l - r where l and r have the same size.
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* This function operates modulo (2^ciL)^n and returns the carry
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* (1 if there was a wraparound, i.e. if `l < r`, and 0 otherwise).
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*
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* d may be aliased to l or r.
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*
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* \param[out] d The result of the subtraction.
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* \param[in] l The left operand.
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* \param[in] r The right operand.
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* \param n Number of limbs of \p d, \p l and \p r.
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*
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* \return 1 if `l < r`.
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* 0 if `l >= r`.
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*/
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mbedtls_mpi_uint MPI_CORE(sub)( mbedtls_mpi_uint *d,
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const mbedtls_mpi_uint *l,
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const mbedtls_mpi_uint *r,
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size_t n );
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/**
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* \brief Constant-time conditional addition of two known-size large unsigned
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* integers, returning the carry.
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*
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* Functionally equivalent to
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*
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* ```
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* if( cond )
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* d += r;
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* return carry;
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* ```
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*
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* \param[in,out] d The pointer to the (little-endian) array
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* representing the bignum to accumulate onto.
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* \param[in] r The pointer to the (little-endian) array
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* representing the bignum to conditionally add
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* to \p d. This must be disjoint from \p d.
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* \param n Number of limbs of \p d and \p r.
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* \param cond Condition bit dictating whether addition should
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* happen or not. This must be \c 0 or \c 1.
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*
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* \return 1 if `d + cond*r >= (2^{ciL})^n`, 0 otherwise.
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*/
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mbedtls_mpi_uint MPI_CORE(add_if)( mbedtls_mpi_uint *d,
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const mbedtls_mpi_uint *r,
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size_t n,
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unsigned cond );
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#endif /* MBEDTLS_BIGNUM_CORE_H */
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126
library/bignum_new.c
Normal file
126
library/bignum_new.c
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@ -0,0 +1,126 @@
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/*
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* Multi-precision integer library
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_BIGNUM_C)
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#include "mbedtls/bignum.h"
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#include "bignum_core.h"
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#include "bn_mul.h"
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#include <string.h>
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void MPI_CORE(montmul)( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_uint *B,
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size_t B_len,
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const mbedtls_mpi_uint *N,
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size_t n,
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mbedtls_mpi_uint mm,
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mbedtls_mpi_uint *T )
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{
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memset( T, 0, (2*n+1)*ciL );
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for( size_t i = 0; i < n; i++, T++ )
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{
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mbedtls_mpi_uint u0, u1;
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/* T = (T + u0*B + u1*N) / 2^biL */
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u0 = A[i];
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u1 = ( T[0] + u0 * B[0] ) * mm;
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(void) MPI_CORE(mla)( T, n + 2, B, B_len, u0 );
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(void) MPI_CORE(mla)( T, n + 2, N, n, u1 );
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}
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mbedtls_mpi_uint carry, borrow, fixup;
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carry = T[n];
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borrow = MPI_CORE(sub)( X, T, N, n );
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fixup = carry < borrow;
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(void) MPI_CORE(add_if)( X, N, n, fixup );
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}
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mbedtls_mpi_uint MPI_CORE(mla)( mbedtls_mpi_uint *d, size_t d_len,
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const mbedtls_mpi_uint *s, size_t s_len,
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mbedtls_mpi_uint b )
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{
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mbedtls_mpi_uint c = 0; /* carry */
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if( d_len < s_len )
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s_len = d_len;
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size_t excess_len = d_len - s_len;
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size_t steps_x8 = s_len / 8;
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size_t steps_x1 = s_len & 7;
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while( steps_x8-- )
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{
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MULADDC_X8_INIT
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MULADDC_X8_CORE
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MULADDC_X8_STOP
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}
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while( steps_x1-- )
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{
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MULADDC_X1_INIT
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MULADDC_X1_CORE
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MULADDC_X1_STOP
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}
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while( excess_len-- )
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{
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*d += c; c = ( *d < c ); d++;
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}
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return( c );
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}
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mbedtls_mpi_uint MPI_CORE(sub)( mbedtls_mpi_uint *d,
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const mbedtls_mpi_uint *l,
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const mbedtls_mpi_uint *r,
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size_t n )
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{
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mbedtls_mpi_uint c = 0, t, z;
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for( size_t i = 0; i < n; i++ )
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{
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z = ( l[i] < c ); t = l[i] - c;
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c = ( t < r[i] ) + z; d[i] = t - r[i];
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}
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return( c );
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}
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mbedtls_mpi_uint MPI_CORE(add_if)( mbedtls_mpi_uint *d,
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const mbedtls_mpi_uint *r,
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size_t n,
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unsigned cond )
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{
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mbedtls_mpi_uint c = 0, t;
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for( size_t i = 0; i < n; i++ )
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{
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mbedtls_mpi_uint add = cond * r[i];
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t = c;
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t += d[i]; c = ( t < d[i] );
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t += add; c += ( t < add );
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d[i] = t;
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}
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return( c );
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}
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#endif /* MBEDTLS_BIGNUM_C */
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