mirror of
https://github.com/espressif/esp-idf.git
synced 2024-10-05 20:47:46 -04:00
649 lines
19 KiB
C
649 lines
19 KiB
C
/*
|
|
* Multi-precision integer library
|
|
* ESP-IDF hardware accelerated parts based on mbedTLS implementation
|
|
*
|
|
* SPDX-FileCopyrightText: The Mbed TLS Contributors
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* SPDX-FileContributor: 2016-2022 Espressif Systems (Shanghai) CO LTD
|
|
*/
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <malloc.h>
|
|
#include <limits.h>
|
|
#include <assert.h>
|
|
#include <stdlib.h>
|
|
#include <sys/param.h>
|
|
|
|
#include "esp_system.h"
|
|
#include "esp_log.h"
|
|
#include "esp_attr.h"
|
|
#include "esp_intr_alloc.h"
|
|
#include "esp_pm.h"
|
|
|
|
#include "freertos/FreeRTOS.h"
|
|
#include "freertos/semphr.h"
|
|
|
|
#include "soc/hwcrypto_periph.h"
|
|
#include "soc/periph_defs.h"
|
|
#include "soc/soc_caps.h"
|
|
|
|
#include "bignum_impl.h"
|
|
|
|
#include <mbedtls/bignum.h>
|
|
|
|
|
|
/* Some implementation notes:
|
|
*
|
|
* - Naming convention x_words, y_words, z_words for number of words (limbs) used in a particular
|
|
* bignum. This number may be less than the size of the bignum
|
|
*
|
|
* - Naming convention hw_words for the hardware length of the operation. This number maybe be rounded up
|
|
* for targets that requres this (e.g. ESP32), and may be larger than any of the numbers
|
|
* involved in the calculation.
|
|
*
|
|
* - Timing behaviour of these functions will depend on the length of the inputs. This is fundamentally
|
|
* the same constraint as the software mbedTLS implementations, and relies on the same
|
|
* countermeasures (exponent blinding, etc) which are used in mbedTLS.
|
|
*/
|
|
|
|
static const __attribute__((unused)) char *TAG = "bignum";
|
|
|
|
#define ciL (sizeof(mbedtls_mpi_uint)) /* chars in limb */
|
|
#define biL (ciL << 3) /* bits in limb */
|
|
|
|
#if defined(CONFIG_MBEDTLS_MPI_USE_INTERRUPT)
|
|
static SemaphoreHandle_t op_complete_sem;
|
|
#if defined(CONFIG_PM_ENABLE)
|
|
static esp_pm_lock_handle_t s_pm_cpu_lock;
|
|
static esp_pm_lock_handle_t s_pm_sleep_lock;
|
|
#endif
|
|
|
|
static IRAM_ATTR void esp_mpi_complete_isr(void *arg)
|
|
{
|
|
BaseType_t higher_woken;
|
|
esp_mpi_interrupt_clear();
|
|
|
|
xSemaphoreGiveFromISR(op_complete_sem, &higher_woken);
|
|
if (higher_woken) {
|
|
portYIELD_FROM_ISR();
|
|
}
|
|
}
|
|
|
|
|
|
static esp_err_t esp_mpi_isr_initialise(void)
|
|
{
|
|
esp_mpi_interrupt_clear();
|
|
esp_mpi_interrupt_enable(true);
|
|
if (op_complete_sem == NULL) {
|
|
op_complete_sem = xSemaphoreCreateBinary();
|
|
|
|
if (op_complete_sem == NULL) {
|
|
ESP_LOGE(TAG, "Failed to create intr semaphore");
|
|
return ESP_FAIL;
|
|
}
|
|
|
|
esp_intr_alloc(ETS_RSA_INTR_SOURCE, 0, esp_mpi_complete_isr, NULL, NULL);
|
|
}
|
|
|
|
/* MPI is clocked proportionally to CPU clock, take power management lock */
|
|
#ifdef CONFIG_PM_ENABLE
|
|
if (s_pm_cpu_lock == NULL) {
|
|
if (esp_pm_lock_create(ESP_PM_NO_LIGHT_SLEEP, 0, "mpi_sleep", &s_pm_sleep_lock) != ESP_OK) {
|
|
ESP_LOGE(TAG, "Failed to create PM sleep lock");
|
|
return ESP_FAIL;
|
|
}
|
|
if (esp_pm_lock_create(ESP_PM_CPU_FREQ_MAX, 0, "mpi_cpu", &s_pm_cpu_lock) != ESP_OK) {
|
|
ESP_LOGE(TAG, "Failed to create PM CPU lock");
|
|
return ESP_FAIL;
|
|
}
|
|
}
|
|
esp_pm_lock_acquire(s_pm_cpu_lock);
|
|
esp_pm_lock_acquire(s_pm_sleep_lock);
|
|
#endif
|
|
|
|
return ESP_OK;
|
|
}
|
|
|
|
static int esp_mpi_wait_intr(void)
|
|
{
|
|
if (!xSemaphoreTake(op_complete_sem, 2000 / portTICK_PERIOD_MS)) {
|
|
ESP_LOGE("MPI", "Timed out waiting for completion of MPI Interrupt");
|
|
return -1;
|
|
}
|
|
|
|
#ifdef CONFIG_PM_ENABLE
|
|
esp_pm_lock_release(s_pm_cpu_lock);
|
|
esp_pm_lock_release(s_pm_sleep_lock);
|
|
#endif // CONFIG_PM_ENABLE
|
|
|
|
esp_mpi_interrupt_enable(false);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif // CONFIG_MBEDTLS_MPI_USE_INTERRUPT
|
|
|
|
/* Convert bit count to word count
|
|
*/
|
|
static inline size_t bits_to_words(size_t bits)
|
|
{
|
|
return (bits + 31) / 32;
|
|
}
|
|
|
|
/* Return the number of words actually used to represent an mpi
|
|
number.
|
|
*/
|
|
#if defined(MBEDTLS_MPI_EXP_MOD_ALT) || defined(MBEDTLS_MPI_EXP_MOD_ALT_FALLBACK)
|
|
static size_t mpi_words(const mbedtls_mpi *mpi)
|
|
{
|
|
for (size_t i = mpi->MBEDTLS_PRIVATE(n); i > 0; i--) {
|
|
if (mpi->MBEDTLS_PRIVATE(p[i - 1]) != 0) {
|
|
return i;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
#endif //(MBEDTLS_MPI_EXP_MOD_ALT || MBEDTLS_MPI_EXP_MOD_ALT_FALLBACK)
|
|
|
|
/**
|
|
*
|
|
* There is a need for the value of integer N' such that B^-1(B-1)-N^-1N'=1,
|
|
* where B^-1(B-1) mod N=1. Actually, only the least significant part of
|
|
* N' is needed, hence the definition N0'=N' mod b. We reproduce below the
|
|
* simple algorithm from an article by Dusse and Kaliski to efficiently
|
|
* find N0' from N0 and b
|
|
*/
|
|
static mbedtls_mpi_uint modular_inverse(const mbedtls_mpi *M)
|
|
{
|
|
int i;
|
|
uint64_t t = 1;
|
|
uint64_t two_2_i_minus_1 = 2; /* 2^(i-1) */
|
|
uint64_t two_2_i = 4; /* 2^i */
|
|
uint64_t N = M->MBEDTLS_PRIVATE(p[0]);
|
|
|
|
for (i = 2; i <= 32; i++) {
|
|
if ((mbedtls_mpi_uint) N * t % two_2_i >= two_2_i_minus_1) {
|
|
t += two_2_i_minus_1;
|
|
}
|
|
|
|
two_2_i_minus_1 <<= 1;
|
|
two_2_i <<= 1;
|
|
}
|
|
|
|
return (mbedtls_mpi_uint)(UINT32_MAX - t + 1);
|
|
}
|
|
|
|
/* Calculate Rinv = RR^2 mod M, where:
|
|
*
|
|
* R = b^n where b = 2^32, n=num_words,
|
|
* R = 2^N (where N=num_bits)
|
|
* RR = R^2 = 2^(2*N) (where N=num_bits=num_words*32)
|
|
*
|
|
* This calculation is computationally expensive (mbedtls_mpi_mod_mpi)
|
|
* so caller should cache the result where possible.
|
|
*
|
|
* DO NOT call this function while holding esp_mpi_enable_hardware_hw_op().
|
|
*
|
|
*/
|
|
static int calculate_rinv(mbedtls_mpi *Rinv, const mbedtls_mpi *M, int num_words)
|
|
{
|
|
int ret;
|
|
size_t num_bits = num_words * 32;
|
|
mbedtls_mpi RR;
|
|
mbedtls_mpi_init(&RR);
|
|
MBEDTLS_MPI_CHK(mbedtls_mpi_set_bit(&RR, num_bits * 2, 1));
|
|
MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(Rinv, &RR, M));
|
|
|
|
cleanup:
|
|
mbedtls_mpi_free(&RR);
|
|
|
|
return ret;
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/* Z = (X * Y) mod M
|
|
|
|
Not an mbedTLS function
|
|
*/
|
|
int esp_mpi_mul_mpi_mod(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, const mbedtls_mpi *M)
|
|
{
|
|
int ret = 0;
|
|
|
|
size_t x_bits = mbedtls_mpi_bitlen(X);
|
|
size_t y_bits = mbedtls_mpi_bitlen(Y);
|
|
size_t m_bits = mbedtls_mpi_bitlen(M);
|
|
size_t z_bits = MIN(m_bits, x_bits + y_bits);
|
|
size_t x_words = bits_to_words(x_bits);
|
|
size_t y_words = bits_to_words(y_bits);
|
|
size_t m_words = bits_to_words(m_bits);
|
|
size_t z_words = bits_to_words(z_bits);
|
|
size_t hw_words = esp_mpi_hardware_words(MAX(x_words, MAX(y_words, m_words))); /* longest operand */
|
|
mbedtls_mpi Rinv;
|
|
mbedtls_mpi_uint Mprime;
|
|
|
|
/* Calculate and load the first stage montgomery multiplication */
|
|
mbedtls_mpi_init(&Rinv);
|
|
MBEDTLS_MPI_CHK(calculate_rinv(&Rinv, M, hw_words));
|
|
Mprime = modular_inverse(M);
|
|
|
|
esp_mpi_enable_hardware_hw_op();
|
|
/* Load and start a (X * Y) mod M calculation */
|
|
esp_mpi_mul_mpi_mod_hw_op(X, Y, M, &Rinv, Mprime, hw_words);
|
|
|
|
MBEDTLS_MPI_CHK(mbedtls_mpi_grow(Z, z_words));
|
|
|
|
esp_mpi_read_result_hw_op(Z, z_words);
|
|
Z->MBEDTLS_PRIVATE(s) = X->MBEDTLS_PRIVATE(s) * Y->MBEDTLS_PRIVATE(s);
|
|
|
|
cleanup:
|
|
mbedtls_mpi_free(&Rinv);
|
|
esp_mpi_disable_hardware_hw_op();
|
|
|
|
return ret;
|
|
}
|
|
|
|
#if defined(MBEDTLS_MPI_EXP_MOD_ALT) || defined(MBEDTLS_MPI_EXP_MOD_ALT_FALLBACK)
|
|
|
|
#ifdef ESP_MPI_USE_MONT_EXP
|
|
/*
|
|
* Return the most significant one-bit.
|
|
*/
|
|
static size_t mbedtls_mpi_msb( const mbedtls_mpi *X )
|
|
{
|
|
int i, j;
|
|
if (X != NULL && X->MBEDTLS_PRIVATE(n) != 0) {
|
|
for (i = X->MBEDTLS_PRIVATE(n) - 1; i >= 0; i--) {
|
|
if (X->MBEDTLS_PRIVATE(p[i]) != 0) {
|
|
for (j = biL - 1; j >= 0; j--) {
|
|
if ((X->MBEDTLS_PRIVATE(p[i]) & (1 << j)) != 0) {
|
|
return (i * biL) + j;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Montgomery exponentiation: Z = X ^ Y mod M (HAC 14.94)
|
|
*/
|
|
static int mpi_montgomery_exp_calc( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, const mbedtls_mpi *M,
|
|
mbedtls_mpi *Rinv,
|
|
size_t hw_words,
|
|
mbedtls_mpi_uint Mprime )
|
|
{
|
|
int ret = 0;
|
|
mbedtls_mpi X_, one;
|
|
|
|
mbedtls_mpi_init(&X_);
|
|
mbedtls_mpi_init(&one);
|
|
if ( ( ( ret = mbedtls_mpi_grow(&one, hw_words) ) != 0 ) ||
|
|
( ( ret = mbedtls_mpi_set_bit(&one, 0, 1) ) != 0 ) ) {
|
|
goto cleanup2;
|
|
}
|
|
|
|
// Algorithm from HAC 14.94
|
|
{
|
|
// 0 determine t (highest bit set in y)
|
|
int t = mbedtls_mpi_msb(Y);
|
|
|
|
esp_mpi_enable_hardware_hw_op();
|
|
|
|
// 1.1 x_ = mont(x, R^2 mod m)
|
|
// = mont(x, rb)
|
|
MBEDTLS_MPI_CHK( esp_mont_hw_op(&X_, X, Rinv, M, Mprime, hw_words, false) );
|
|
|
|
// 1.2 z = R mod m
|
|
// now z = R mod m = Mont (R^2 mod m, 1) mod M (as Mont(x) = X&R^-1 mod M)
|
|
MBEDTLS_MPI_CHK( esp_mont_hw_op(Z, Rinv, &one, M, Mprime, hw_words, true) );
|
|
|
|
// 2 for i from t down to 0
|
|
for (int i = t; i >= 0; i--) {
|
|
// 2.1 z = mont(z,z)
|
|
if (i != t) { // skip on the first iteration as is still unity
|
|
MBEDTLS_MPI_CHK( esp_mont_hw_op(Z, Z, Z, M, Mprime, hw_words, true) );
|
|
}
|
|
|
|
// 2.2 if y[i] = 1 then z = mont(A, x_)
|
|
if (mbedtls_mpi_get_bit(Y, i)) {
|
|
MBEDTLS_MPI_CHK( esp_mont_hw_op(Z, Z, &X_, M, Mprime, hw_words, true) );
|
|
}
|
|
}
|
|
|
|
// 3 z = Mont(z, 1)
|
|
MBEDTLS_MPI_CHK( esp_mont_hw_op(Z, Z, &one, M, Mprime, hw_words, true) );
|
|
}
|
|
|
|
cleanup:
|
|
esp_mpi_disable_hardware_hw_op();
|
|
|
|
cleanup2:
|
|
mbedtls_mpi_free(&X_);
|
|
mbedtls_mpi_free(&one);
|
|
return ret;
|
|
}
|
|
|
|
#endif //USE_MONT_EXPONENATIATION
|
|
|
|
/*
|
|
* Z = X ^ Y mod M
|
|
*
|
|
* _Rinv is optional pre-calculated version of Rinv (via calculate_rinv()).
|
|
*
|
|
* (See RSA Accelerator section in Technical Reference for more about Mprime, Rinv)
|
|
*
|
|
*/
|
|
static int esp_mpi_exp_mod( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, const mbedtls_mpi *M, mbedtls_mpi *_Rinv )
|
|
{
|
|
int ret = 0;
|
|
|
|
mbedtls_mpi Rinv_new; /* used if _Rinv == NULL */
|
|
mbedtls_mpi *Rinv; /* points to _Rinv (if not NULL) othwerwise &RR_new */
|
|
mbedtls_mpi_uint Mprime;
|
|
|
|
size_t x_words = mpi_words(X);
|
|
size_t y_words = mpi_words(Y);
|
|
size_t m_words = mpi_words(M);
|
|
|
|
/* "all numbers must be the same length", so choose longest number
|
|
as cardinal length of operation...
|
|
*/
|
|
size_t num_words = esp_mpi_hardware_words(MAX(m_words, MAX(x_words, y_words)));
|
|
|
|
if (num_words * 32 > SOC_RSA_MAX_BIT_LEN) {
|
|
return MBEDTLS_ERR_MPI_NOT_ACCEPTABLE;
|
|
}
|
|
|
|
if (mbedtls_mpi_cmp_int(M, 0) <= 0 || (M->MBEDTLS_PRIVATE(p[0]) & 1) == 0) {
|
|
return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
|
|
}
|
|
|
|
if (mbedtls_mpi_cmp_int(Y, 0) < 0) {
|
|
return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
|
|
}
|
|
|
|
if (mbedtls_mpi_cmp_int(Y, 0) == 0) {
|
|
return mbedtls_mpi_lset(Z, 1);
|
|
}
|
|
|
|
/* Determine RR pointer, either _RR for cached value
|
|
or local RR_new */
|
|
if (_Rinv == NULL) {
|
|
mbedtls_mpi_init(&Rinv_new);
|
|
Rinv = &Rinv_new;
|
|
} else {
|
|
Rinv = _Rinv;
|
|
}
|
|
if (Rinv->MBEDTLS_PRIVATE(p) == NULL) {
|
|
MBEDTLS_MPI_CHK(calculate_rinv(Rinv, M, num_words));
|
|
}
|
|
|
|
Mprime = modular_inverse(M);
|
|
|
|
// Montgomery exponentiation: Z = X ^ Y mod M (HAC 14.94)
|
|
#ifdef ESP_MPI_USE_MONT_EXP
|
|
ret = mpi_montgomery_exp_calc(Z, X, Y, M, Rinv, num_words, Mprime) ;
|
|
MBEDTLS_MPI_CHK(ret);
|
|
#else
|
|
esp_mpi_enable_hardware_hw_op();
|
|
|
|
#if defined (CONFIG_MBEDTLS_MPI_USE_INTERRUPT)
|
|
if (esp_mpi_isr_initialise() == ESP_FAIL) {
|
|
ret = -1;
|
|
esp_mpi_disable_hardware_hw_op();
|
|
goto cleanup;
|
|
}
|
|
#endif
|
|
|
|
esp_mpi_exp_mpi_mod_hw_op(X, Y, M, Rinv, Mprime, num_words);
|
|
ret = mbedtls_mpi_grow(Z, m_words);
|
|
if (ret != 0) {
|
|
esp_mpi_disable_hardware_hw_op();
|
|
goto cleanup;
|
|
}
|
|
|
|
#if defined(CONFIG_MBEDTLS_MPI_USE_INTERRUPT)
|
|
ret = esp_mpi_wait_intr();
|
|
if (ret != 0) {
|
|
esp_mpi_disable_hardware_hw_op();
|
|
goto cleanup;
|
|
}
|
|
#endif //CONFIG_MBEDTLS_MPI_USE_INTERRUPT
|
|
|
|
esp_mpi_read_result_hw_op(Z, m_words);
|
|
esp_mpi_disable_hardware_hw_op();
|
|
#endif
|
|
|
|
// Compensate for negative X
|
|
if (X->MBEDTLS_PRIVATE(s) == -1 && (Y->MBEDTLS_PRIVATE(p[0]) & 1) != 0) {
|
|
Z->MBEDTLS_PRIVATE(s) = -1;
|
|
MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(Z, M, Z));
|
|
} else {
|
|
Z->MBEDTLS_PRIVATE(s) = 1;
|
|
}
|
|
|
|
cleanup:
|
|
if (_Rinv == NULL) {
|
|
mbedtls_mpi_free(&Rinv_new);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
#endif /* (MBEDTLS_MPI_EXP_MOD_ALT || MBEDTLS_MPI_EXP_MOD_ALT_FALLBACK) */
|
|
|
|
/*
|
|
* Sliding-window exponentiation: X = A^E mod N (HAC 14.85)
|
|
*/
|
|
int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
|
|
const mbedtls_mpi *E, const mbedtls_mpi *N,
|
|
mbedtls_mpi *_RR )
|
|
{
|
|
int ret;
|
|
#if defined(MBEDTLS_MPI_EXP_MOD_ALT_FALLBACK)
|
|
/* Try hardware API first and then fallback to software */
|
|
ret = esp_mpi_exp_mod( X, A, E, N, _RR );
|
|
if( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE ) {
|
|
ret = mbedtls_mpi_exp_mod_soft( X, A, E, N, _RR );
|
|
}
|
|
#else
|
|
/* Hardware approach */
|
|
ret = esp_mpi_exp_mod( X, A, E, N, _RR );
|
|
#endif
|
|
/* Note: For software only approach, it gets handled in mbedTLS library.
|
|
This file is not part of build objects for that case */
|
|
|
|
return ret;
|
|
}
|
|
|
|
#if defined(MBEDTLS_MPI_MUL_MPI_ALT) /* MBEDTLS_MPI_MUL_MPI_ALT */
|
|
|
|
static int mpi_mult_mpi_failover_mod_mult( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t z_words);
|
|
static int mpi_mult_mpi_overlong(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t y_words, size_t z_words);
|
|
|
|
/* Z = X * Y */
|
|
int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y )
|
|
{
|
|
int ret = 0;
|
|
size_t x_bits = mbedtls_mpi_bitlen(X);
|
|
size_t y_bits = mbedtls_mpi_bitlen(Y);
|
|
size_t x_words = bits_to_words(x_bits);
|
|
size_t y_words = bits_to_words(y_bits);
|
|
size_t z_words = bits_to_words(x_bits + y_bits);
|
|
size_t hw_words = esp_mpi_hardware_words(MAX(x_words, y_words)); // length of one operand in hardware
|
|
|
|
/* Short-circuit eval if either argument is 0 or 1.
|
|
|
|
This is needed as the mpi modular division
|
|
argument will sometimes call in here when one
|
|
argument is too large for the hardware unit, but the other
|
|
argument is zero or one.
|
|
*/
|
|
if (x_bits == 0 || y_bits == 0) {
|
|
mbedtls_mpi_lset(Z, 0);
|
|
return 0;
|
|
}
|
|
if (x_bits == 1) {
|
|
ret = mbedtls_mpi_copy(Z, Y);
|
|
Z->MBEDTLS_PRIVATE(s) *= X->MBEDTLS_PRIVATE(s);
|
|
return ret;
|
|
}
|
|
if (y_bits == 1) {
|
|
ret = mbedtls_mpi_copy(Z, X);
|
|
Z->MBEDTLS_PRIVATE(s) *= Y->MBEDTLS_PRIVATE(s);
|
|
return ret;
|
|
}
|
|
|
|
/* Grow Z to result size early, avoid interim allocations */
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_grow(Z, z_words) );
|
|
|
|
/* If either factor is over 2048 bits, we can't use the standard hardware multiplier
|
|
(it assumes result is double longest factor, and result is max 4096 bits.)
|
|
|
|
However, we can fail over to mod_mult for up to 4096 bits of result (modulo
|
|
multiplication doesn't have the same restriction, so result is simply the
|
|
number of bits in X plus number of bits in in Y.)
|
|
*/
|
|
if (hw_words * 32 > SOC_RSA_MAX_BIT_LEN/2) {
|
|
if (z_words * 32 <= SOC_RSA_MAX_BIT_LEN) {
|
|
/* Note: it's possible to use mpi_mult_mpi_overlong
|
|
for this case as well, but it's very slightly
|
|
slower and requires a memory allocation.
|
|
*/
|
|
return mpi_mult_mpi_failover_mod_mult(Z, X, Y, z_words);
|
|
} else {
|
|
/* Still too long for the hardware unit... */
|
|
if (y_words > x_words) {
|
|
return mpi_mult_mpi_overlong(Z, X, Y, y_words, z_words);
|
|
} else {
|
|
return mpi_mult_mpi_overlong(Z, Y, X, x_words, z_words);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Otherwise, we can use the (faster) multiply hardware unit */
|
|
esp_mpi_enable_hardware_hw_op();
|
|
|
|
esp_mpi_mul_mpi_hw_op(X, Y, hw_words);
|
|
esp_mpi_read_result_hw_op(Z, z_words);
|
|
|
|
esp_mpi_disable_hardware_hw_op();
|
|
|
|
Z->MBEDTLS_PRIVATE(s) = X->MBEDTLS_PRIVATE(s) * Y->MBEDTLS_PRIVATE(s);
|
|
|
|
cleanup:
|
|
return ret;
|
|
}
|
|
|
|
int mbedtls_mpi_mul_int( mbedtls_mpi *X, const mbedtls_mpi *A, mbedtls_mpi_uint b )
|
|
{
|
|
mbedtls_mpi _B;
|
|
mbedtls_mpi_uint p[1];
|
|
|
|
_B.MBEDTLS_PRIVATE(s) = 1;
|
|
_B.MBEDTLS_PRIVATE(n) = 1;
|
|
_B.MBEDTLS_PRIVATE(p) = p;
|
|
p[0] = b;
|
|
|
|
return( mbedtls_mpi_mul_mpi( X, A, &_B ) );
|
|
}
|
|
|
|
/* Deal with the case when X & Y are too long for the hardware unit, by splitting one operand
|
|
into two halves.
|
|
|
|
Y must be the longer operand
|
|
|
|
Slice Y into Yp, Ypp such that:
|
|
Yp = lower 'b' bits of Y
|
|
Ypp = upper 'b' bits of Y (right shifted)
|
|
|
|
Such that
|
|
Z = X * Y
|
|
Z = X * (Yp + Ypp<<b)
|
|
Z = (X * Yp) + (X * Ypp<<b)
|
|
|
|
Note that this function may recurse multiple times, if both X & Y
|
|
are too long for the hardware multiplication unit.
|
|
*/
|
|
static int mpi_mult_mpi_overlong(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t y_words, size_t z_words)
|
|
{
|
|
int ret = 0;
|
|
mbedtls_mpi Ztemp;
|
|
/* Rather than slicing in two on bits we slice on limbs (32 bit words) */
|
|
const size_t words_slice = y_words / 2;
|
|
/* Yp holds lower bits of Y (declared to reuse Y's array contents to save on copying) */
|
|
const mbedtls_mpi Yp = {
|
|
.MBEDTLS_PRIVATE(p) = Y->MBEDTLS_PRIVATE(p),
|
|
.MBEDTLS_PRIVATE(n) = words_slice,
|
|
.MBEDTLS_PRIVATE(s) = Y->MBEDTLS_PRIVATE(s)
|
|
};
|
|
/* Ypp holds upper bits of Y, right shifted (also reuses Y's array contents) */
|
|
const mbedtls_mpi Ypp = {
|
|
.MBEDTLS_PRIVATE(p) = Y->MBEDTLS_PRIVATE(p) + words_slice,
|
|
.MBEDTLS_PRIVATE(n) = y_words - words_slice,
|
|
.MBEDTLS_PRIVATE(s) = Y->MBEDTLS_PRIVATE(s)
|
|
};
|
|
mbedtls_mpi_init(&Ztemp);
|
|
|
|
/* Get result Ztemp = Yp * X (need temporary variable Ztemp) */
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi(&Ztemp, X, &Yp) );
|
|
|
|
/* Z = Ypp * Y */
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi(Z, X, &Ypp) );
|
|
|
|
/* Z = Z << b */
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_shift_l(Z, words_slice * 32) );
|
|
|
|
/* Z += Ztemp */
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi(Z, Z, &Ztemp) );
|
|
|
|
cleanup:
|
|
mbedtls_mpi_free(&Ztemp);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* Special-case of mbedtls_mpi_mult_mpi(), where we use hardware montgomery mod
|
|
multiplication to calculate an mbedtls_mpi_mult_mpi result where either
|
|
A or B are >2048 bits so can't use the standard multiplication method.
|
|
|
|
Result (number of words, based on A bits + B bits) must still be less than 4096 bits.
|
|
|
|
This case is simpler than the general case modulo multiply of
|
|
esp_mpi_mul_mpi_mod() because we can control the other arguments:
|
|
|
|
* Modulus is chosen with M=(2^num_bits - 1) (ie M=R-1), so output
|
|
* Mprime and Rinv are therefore predictable as follows:
|
|
isn't actually modulo anything.
|
|
Mprime 1
|
|
Rinv 1
|
|
|
|
(See RSA Accelerator section in Technical Reference for more about Mprime, Rinv)
|
|
*/
|
|
|
|
static int mpi_mult_mpi_failover_mod_mult( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t z_words)
|
|
{
|
|
int ret;
|
|
size_t hw_words = esp_mpi_hardware_words(z_words);
|
|
|
|
esp_mpi_enable_hardware_hw_op();
|
|
|
|
esp_mpi_mult_mpi_failover_mod_mult_hw_op(X, Y, hw_words );
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_grow(Z, hw_words) );
|
|
esp_mpi_read_result_hw_op(Z, hw_words);
|
|
|
|
Z->MBEDTLS_PRIVATE(s) = X->MBEDTLS_PRIVATE(s) * Y->MBEDTLS_PRIVATE(s);
|
|
cleanup:
|
|
esp_mpi_disable_hardware_hw_op();
|
|
return ret;
|
|
}
|
|
|
|
#endif /* MBEDTLS_MPI_MUL_MPI_ALT */
|