| /* |
| * Low-level modular bignum functions |
| * |
| * Copyright The Mbed TLS Contributors |
| * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later |
| */ |
| |
| #include "common.h" |
| |
| #if defined(MBEDTLS_BIGNUM_C) && defined(MBEDTLS_ECP_WITH_MPI_UINT) |
| |
| #include <string.h> |
| |
| #include "mbedtls/error.h" |
| #include "mbedtls/platform_util.h" |
| |
| #include "mbedtls/platform.h" |
| |
| #include "bignum_core.h" |
| #include "bignum_mod_raw.h" |
| #include "bignum_mod.h" |
| #include "constant_time_internal.h" |
| |
| #include "bignum_mod_raw_invasive.h" |
| |
| void mbedtls_mpi_mod_raw_cond_assign(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_mod_modulus *N, |
| unsigned char assign) |
| { |
| mbedtls_mpi_core_cond_assign(X, A, N->limbs, mbedtls_ct_bool(assign)); |
| } |
| |
| void mbedtls_mpi_mod_raw_cond_swap(mbedtls_mpi_uint *X, |
| mbedtls_mpi_uint *Y, |
| const mbedtls_mpi_mod_modulus *N, |
| unsigned char swap) |
| { |
| mbedtls_mpi_core_cond_swap(X, Y, N->limbs, mbedtls_ct_bool(swap)); |
| } |
| |
| int mbedtls_mpi_mod_raw_read(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_mod_modulus *N, |
| const unsigned char *input, |
| size_t input_length, |
| mbedtls_mpi_mod_ext_rep ext_rep) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| |
| switch (ext_rep) { |
| case MBEDTLS_MPI_MOD_EXT_REP_LE: |
| ret = mbedtls_mpi_core_read_le(X, N->limbs, |
| input, input_length); |
| break; |
| case MBEDTLS_MPI_MOD_EXT_REP_BE: |
| ret = mbedtls_mpi_core_read_be(X, N->limbs, |
| input, input_length); |
| break; |
| default: |
| return MBEDTLS_ERR_MPI_BAD_INPUT_DATA; |
| } |
| |
| if (ret != 0) { |
| goto cleanup; |
| } |
| |
| if (!mbedtls_mpi_core_lt_ct(X, N->p, N->limbs)) { |
| ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA; |
| goto cleanup; |
| } |
| |
| cleanup: |
| |
| return ret; |
| } |
| |
| int mbedtls_mpi_mod_raw_write(const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_mod_modulus *N, |
| unsigned char *output, |
| size_t output_length, |
| mbedtls_mpi_mod_ext_rep ext_rep) |
| { |
| switch (ext_rep) { |
| case MBEDTLS_MPI_MOD_EXT_REP_LE: |
| return mbedtls_mpi_core_write_le(A, N->limbs, |
| output, output_length); |
| case MBEDTLS_MPI_MOD_EXT_REP_BE: |
| return mbedtls_mpi_core_write_be(A, N->limbs, |
| output, output_length); |
| default: |
| return MBEDTLS_ERR_MPI_BAD_INPUT_DATA; |
| } |
| } |
| |
| void mbedtls_mpi_mod_raw_sub(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_uint *B, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| mbedtls_mpi_uint c = mbedtls_mpi_core_sub(X, A, B, N->limbs); |
| |
| (void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) c); |
| } |
| |
| MBEDTLS_STATIC_TESTABLE |
| void mbedtls_mpi_mod_raw_fix_quasi_reduction(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| mbedtls_mpi_uint c = mbedtls_mpi_core_sub(X, X, N->p, N->limbs); |
| |
| (void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) c); |
| } |
| |
| |
| void mbedtls_mpi_mod_raw_mul(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_uint *B, |
| const mbedtls_mpi_mod_modulus *N, |
| mbedtls_mpi_uint *T) |
| { |
| /* Standard (A * B) multiplication stored into pre-allocated T |
| * buffer of fixed limb size of (2N + 1). |
| * |
| * The space may not not fully filled by when |
| * MBEDTLS_MPI_MOD_REP_OPT_RED is used. */ |
| const size_t T_limbs = BITS_TO_LIMBS(N->bits) * 2; |
| switch (N->int_rep) { |
| case MBEDTLS_MPI_MOD_REP_MONTGOMERY: |
| mbedtls_mpi_core_montmul(X, A, B, N->limbs, N->p, N->limbs, |
| N->rep.mont.mm, T); |
| break; |
| case MBEDTLS_MPI_MOD_REP_OPT_RED: |
| mbedtls_mpi_core_mul(T, A, N->limbs, B, N->limbs); |
| |
| /* Optimised Reduction */ |
| (*N->rep.ored.modp)(T, T_limbs); |
| |
| /* Convert back to canonical representation */ |
| mbedtls_mpi_mod_raw_fix_quasi_reduction(T, N); |
| memcpy(X, T, N->limbs * sizeof(mbedtls_mpi_uint)); |
| break; |
| default: |
| break; |
| } |
| |
| } |
| |
| size_t mbedtls_mpi_mod_raw_inv_prime_working_limbs(size_t AN_limbs) |
| { |
| /* mbedtls_mpi_mod_raw_inv_prime() needs a temporary for the exponent, |
| * which will be the same size as the modulus and input (AN_limbs), |
| * and additional space to pass to mbedtls_mpi_core_exp_mod(). */ |
| return AN_limbs + |
| mbedtls_mpi_core_exp_mod_working_limbs(AN_limbs, AN_limbs); |
| } |
| |
| void mbedtls_mpi_mod_raw_inv_prime(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_uint *N, |
| size_t AN_limbs, |
| const mbedtls_mpi_uint *RR, |
| mbedtls_mpi_uint *T) |
| { |
| /* Inversion by power: g^|G| = 1 => g^(-1) = g^(|G|-1), and |
| * |G| = N - 1, so we want |
| * g^(|G|-1) = g^(N - 2) |
| */ |
| |
| /* Use the first AN_limbs of T to hold N - 2 */ |
| mbedtls_mpi_uint *Nminus2 = T; |
| (void) mbedtls_mpi_core_sub_int(Nminus2, N, 2, AN_limbs); |
| |
| /* Rest of T is given to exp_mod for its working space */ |
| mbedtls_mpi_core_exp_mod(X, |
| A, N, AN_limbs, Nminus2, AN_limbs, |
| RR, T + AN_limbs); |
| } |
| |
| void mbedtls_mpi_mod_raw_add(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_uint *B, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| mbedtls_mpi_uint carry, borrow; |
| carry = mbedtls_mpi_core_add(X, A, B, N->limbs); |
| borrow = mbedtls_mpi_core_sub(X, X, N->p, N->limbs); |
| (void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) (carry ^ borrow)); |
| } |
| |
| int mbedtls_mpi_mod_raw_canonical_to_modulus_rep( |
| mbedtls_mpi_uint *X, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| switch (N->int_rep) { |
| case MBEDTLS_MPI_MOD_REP_MONTGOMERY: |
| return mbedtls_mpi_mod_raw_to_mont_rep(X, N); |
| case MBEDTLS_MPI_MOD_REP_OPT_RED: |
| return 0; |
| default: |
| return MBEDTLS_ERR_MPI_BAD_INPUT_DATA; |
| } |
| } |
| |
| int mbedtls_mpi_mod_raw_modulus_to_canonical_rep( |
| mbedtls_mpi_uint *X, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| switch (N->int_rep) { |
| case MBEDTLS_MPI_MOD_REP_MONTGOMERY: |
| return mbedtls_mpi_mod_raw_from_mont_rep(X, N); |
| case MBEDTLS_MPI_MOD_REP_OPT_RED: |
| return 0; |
| default: |
| return MBEDTLS_ERR_MPI_BAD_INPUT_DATA; |
| } |
| } |
| |
| int mbedtls_mpi_mod_raw_random(mbedtls_mpi_uint *X, |
| mbedtls_mpi_uint min, |
| const mbedtls_mpi_mod_modulus *N, |
| int (*f_rng)(void *, unsigned char *, size_t), |
| void *p_rng) |
| { |
| int ret = mbedtls_mpi_core_random(X, min, N->p, N->limbs, f_rng, p_rng); |
| if (ret != 0) { |
| return ret; |
| } |
| return mbedtls_mpi_mod_raw_canonical_to_modulus_rep(X, N); |
| } |
| |
| int mbedtls_mpi_mod_raw_to_mont_rep(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| mbedtls_mpi_uint *T; |
| const size_t t_limbs = mbedtls_mpi_core_montmul_working_limbs(N->limbs); |
| |
| if ((T = (mbedtls_mpi_uint *) mbedtls_calloc(t_limbs, ciL)) == NULL) { |
| return MBEDTLS_ERR_MPI_ALLOC_FAILED; |
| } |
| |
| mbedtls_mpi_core_to_mont_rep(X, X, N->p, N->limbs, |
| N->rep.mont.mm, N->rep.mont.rr, T); |
| |
| mbedtls_zeroize_and_free(T, t_limbs * ciL); |
| return 0; |
| } |
| |
| int mbedtls_mpi_mod_raw_from_mont_rep(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| const size_t t_limbs = mbedtls_mpi_core_montmul_working_limbs(N->limbs); |
| mbedtls_mpi_uint *T; |
| |
| if ((T = (mbedtls_mpi_uint *) mbedtls_calloc(t_limbs, ciL)) == NULL) { |
| return MBEDTLS_ERR_MPI_ALLOC_FAILED; |
| } |
| |
| mbedtls_mpi_core_from_mont_rep(X, X, N->p, N->limbs, N->rep.mont.mm, T); |
| |
| mbedtls_zeroize_and_free(T, t_limbs * ciL); |
| return 0; |
| } |
| |
| void mbedtls_mpi_mod_raw_neg(mbedtls_mpi_uint *X, |
| const mbedtls_mpi_uint *A, |
| const mbedtls_mpi_mod_modulus *N) |
| { |
| mbedtls_mpi_core_sub(X, N->p, A, N->limbs); |
| |
| /* If A=0 initially, then X=N now. Detect this by |
| * subtracting N and catching the carry. */ |
| mbedtls_mpi_uint borrow = mbedtls_mpi_core_sub(X, X, N->p, N->limbs); |
| (void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) borrow); |
| } |
| |
| #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ECP_WITH_MPI_UINT */ |