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 2022-08-23 12:09:35 +01:00 committed by Tom Cosgrove
parent 82d3f1e824
commit 71f4b0dda6
5 changed files with 229 additions and 1 deletions

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@ -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

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@ -21,6 +21,7 @@ set(src_crypto
bignum_core.c
bignum_mod.c
bignum_mod_raw.c
bignum_new.c
camellia.c
ccm.c
chacha20.c

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@ -86,6 +86,7 @@ OBJS_CRYPTO= \
bignum_core.o \
bignum_mod.o \
bignum_mod_raw.o \
bignum_new.o \
camellia.o \
ccm.o \
chacha20.o \

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@ -172,8 +172,107 @@ int mbedtls_mpi_core_write_be( const mbedtls_mpi_uint *A,
*
* \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 */

126
library/bignum_new.c Normal file
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@ -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 */