mpi: refactor bignum into common and hw specific components

Closes IDF-1174

components/mbedtls/port/include/bignum_impl.h

@@ -0,0 +1,83 @@
+#ifndef _ESP_BIGNUM_H_
+#define _ESP_BIGNUM_H_
+
+#include <mbedtls/bignum.h>
+#include <stdbool.h>
+
+/* Use montgomery exponentiation (HAC 14.94) for calculating X ^ Y mod M,
+   this may be faster for some targets. The hardware acceleration support for modular
+   exponentiation on the ESP32 is slow for public key operations, so use montgomery
+   exponentiation instead.
+*/
+#if CONFIG_IDF_TARGET_ESP32
+#define ESP_MPI_USE_MONT_EXP
+#endif
+
+/**
+ * @brief Enable the MPI hardware
+ *
+ */
+void esp_mpi_enable_hardware_hw_op( void );
+
+/**
+ * @brief Disable the MPI hardware
+ *
+ */
+void esp_mpi_disable_hardware_hw_op( void );
+
+/**
+ * @brief Calculate the number of words needed to represent the input word in hardware
+ *
+ * @param words The number of words to be represented
+ *
+ * @return size_t Number of words required
+ */
+size_t esp_mpi_hardware_words(size_t words);
+
+/**
+ * @brief Starts a (X * Y) Mod M calculation in hardware. Rinv and M_prime needs to be precalculated in software.
+ *
+ */
+void esp_mpi_mul_mpi_mod_hw_op(const mbedtls_mpi *X, const mbedtls_mpi *Y, const mbedtls_mpi *M, const mbedtls_mpi *Rinv, mbedtls_mpi_uint Mprime, size_t hw_words);
+
+/**
+ * @brief Starts a (X * Y) calculation in hardware.
+ *
+ */
+void esp_mpi_mul_mpi_hw_op(const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t num_words);
+
+/**
+ * @brief Special-case of (X * Y), where we use hardware montgomery mod
+   multiplication to calculate result where either A or B are >2048 bits so
+   can't use the standard multiplication method.
+ *
+ */
+void esp_mpi_mult_mpi_failover_mod_mult_hw_op(const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t num_words);
+
+/**
+ * @brief Read out the result from the previous calculation.
+ *
+ */
+void esp_mpi_read_result_hw_op(mbedtls_mpi *Z, size_t z_words);
+
+#ifdef ESP_MPI_USE_MONT_EXP
+/**
+ * @brief Starts a montgomery multiplication calculation in hardware
+ *
+ */
+int esp_mont_hw_op(mbedtls_mpi* Z, const mbedtls_mpi* X, const mbedtls_mpi* Y, const mbedtls_mpi* M,
+                mbedtls_mpi_uint Mprime,
+                size_t hw_words,
+                bool again);
+
+#else
+
+/**
+ * @brief Starts a (X ^ Y) Mod M calculation in hardware. Rinv and M_prime needs to be precalculated in software.
+ *
+ */
+void esp_mpi_exp_mpi_mod_hw_op(const mbedtls_mpi *X, const mbedtls_mpi *Y, const mbedtls_mpi *M, const mbedtls_mpi *Rinv, mbedtls_mpi_uint Mprime, size_t hw_words);
+
+#endif //ESP_MPI_USE_MONT_EXP
+
+#endif