diff --git a/components/mbedtls/port/esp_bignum.c b/components/mbedtls/port/esp_bignum.c index 3bfcd6145..b8f2cf8bf 100644 --- a/components/mbedtls/port/esp_bignum.c +++ b/components/mbedtls/port/esp_bignum.c @@ -26,6 +26,7 @@ #include #include #include +#include #include "mbedtls/bignum.h" #include "rom/bigint.h" #include "soc/hwcrypto_reg.h" @@ -41,6 +42,20 @@ #include "freertos/task.h" #include "freertos/semphr.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 is always + * rounded up to a 512 bit multiple, 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 */ @@ -103,49 +118,49 @@ void esp_mpi_release_hardware( void ) _lock_release(&mpi_lock); } -/* Number of words used to hold 'mpi', rounded up to nearest - 16 words (512 bits) to match hardware support. +/* Convert bit count to word count + */ +static inline size_t bits_to_words(size_t bits) +{ + return (bits + 31) / 32; +} + +/* Round up number of words to nearest + 512 bit (16 word) block count. +*/ +static inline size_t hardware_words(size_t words) +{ + return (words + 0xF) & ~0xF; +} + +/* Number of words used to hold 'mpi'. + + Equivalent of bits_to_words(mbedtls_mpi_bitlen(mpi)), but uses less cycles if the + exact bit count is not needed. Note that mpi->n (size of memory buffer) may be higher than this number, if the high bits are mostly zeroes. - - This implementation may cause the caller to leak a small amount of - timing information when an operation is performed (length of a - given mpi value, rounded to nearest 512 bits), but not all mbedTLS - RSA operations succeed if we use mpi->N as-is (buffers are too long). */ -static inline size_t hardware_words_needed(const mbedtls_mpi *mpi) +static inline size_t word_length(const mbedtls_mpi *mpi) { - size_t res = 1; - for(size_t i = 0; i < mpi->n; i++) { - if( mpi->p[i] != 0 ) { - res = i + 1; + for(size_t i = mpi->n; i > 0; i--) { + if( mpi->p[i - 1] != 0 ) { + return i; } } - res = (res + 0xF) & ~0xF; - return res; -} - -/* Convert number of bits to number of words, rounded up to nearest - 512 bit (16 word) block count. -*/ -static inline size_t bits_to_hardware_words(size_t num_bits) -{ - return ((num_bits + 511) / 512) * 16; + return 0; } /* Copy mbedTLS MPI bignum 'mpi' to hardware memory block at 'mem_base'. - If num_words is higher than the number of words in the bignum then + If hw_words is higher than the number of words in the bignum then these additional words will be zeroed in the memory buffer. - As this function only writes to DPORT memory, no DPORT_STALL_OTHER_CPU_START() - is required. */ -static inline void mpi_to_mem_block(uint32_t mem_base, const mbedtls_mpi *mpi, size_t num_words) +static inline void mpi_to_mem_block(uint32_t mem_base, const mbedtls_mpi *mpi, size_t hw_words) { uint32_t *pbase = (uint32_t *)mem_base; - uint32_t copy_words = num_words < mpi->n ? num_words : mpi->n; + uint32_t copy_words = hw_words < mpi->n ? hw_words : mpi->n; /* Copy MPI data to memory block registers */ for (int i = 0; i < copy_words; i++) { @@ -153,7 +168,7 @@ static inline void mpi_to_mem_block(uint32_t mem_base, const mbedtls_mpi *mpi, s } /* Zero any remaining memory block data */ - for (int i = copy_words; i < num_words; i++) { + for (int i = copy_words; i < hw_words; i++) { pbase[i] = 0; } @@ -164,27 +179,21 @@ static inline void mpi_to_mem_block(uint32_t mem_base, const mbedtls_mpi *mpi, s Reads num_words words from block. - Can return a failure result if fails to grow the MPI result. - - Cannot be called inside DPORT_STALL_OTHER_CPU_START() (as may allocate memory). + Bignum 'x' should already be grown to at least num_words by caller (can be done while + calculation is in progress, to save some cycles) */ -static inline int mem_block_to_mpi(mbedtls_mpi *x, uint32_t mem_base, int num_words) +static inline void mem_block_to_mpi(mbedtls_mpi *x, uint32_t mem_base, int num_words) { - int ret = 0; - - MBEDTLS_MPI_CHK( mbedtls_mpi_grow(x, num_words) ); + assert(x->n >= num_words); /* Copy data from memory block registers */ esp_dport_access_read_buffer(x->p, mem_base, num_words); + /* Zero any remaining limbs in the bignum, if the buffer is bigger than num_words */ for(size_t i = num_words; i < x->n; i++) { x->p[i] = 0; } - - asm volatile ("memw"); - cleanup: - return ret; } @@ -245,9 +254,6 @@ static int calculate_rinv(mbedtls_mpi *Rinv, const mbedtls_mpi *M, int num_words /* Begin an RSA operation. op_reg specifies which 'START' register to write to. - - Because the only DPORT operations here are writes, - does not need protecting via DPORT_STALL_OTHER_CPU_START(); */ static inline void start_op(uint32_t op_reg) { @@ -261,9 +267,6 @@ static inline void start_op(uint32_t op_reg) } /* Wait for an RSA operation to complete. - - This should NOT be called inside a DPORT_STALL_OTHER_CPU_START(), as it will stall the other CPU for an unacceptably long - period (and - depending on config - may require interrupts enabled). */ static inline void wait_op_complete(uint32_t op_reg) { @@ -284,7 +287,7 @@ static inline void wait_op_complete(uint32_t op_reg) } /* Sub-stages of modulo multiplication/exponentiation operations */ -inline static int modular_multiply_finish(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t num_words); +inline static int modular_multiply_finish(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t hw_words, size_t z_words); /* Z = (X * Y) mod M @@ -293,27 +296,33 @@ inline static int modular_multiply_finish(mbedtls_mpi *Z, const mbedtls_mpi *X, int esp_mpi_mul_mpi_mod(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, const mbedtls_mpi *M) { int ret; - size_t num_words = hardware_words_needed(M); + 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 = 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, num_words)); + MBEDTLS_MPI_CHK(calculate_rinv(&Rinv, M, hw_words)); Mprime = modular_inverse(M); esp_mpi_acquire_hardware(); - /* (As the following are all writes to DPORT memory, no DPORT_STALL_OTHER_CPU_START is required.) */ - /* Load M, X, Rinv, Mprime (Mprime is mod 2^32) */ - mpi_to_mem_block(RSA_MEM_M_BLOCK_BASE, M, num_words); - mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, num_words); - mpi_to_mem_block(RSA_MEM_RB_BLOCK_BASE, &Rinv, num_words); + mpi_to_mem_block(RSA_MEM_M_BLOCK_BASE, M, hw_words); + mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, hw_words); + mpi_to_mem_block(RSA_MEM_RB_BLOCK_BASE, &Rinv, hw_words); DPORT_REG_WRITE(RSA_M_DASH_REG, (uint32_t)Mprime); /* "mode" register loaded with number of 512-bit blocks, minus 1 */ - DPORT_REG_WRITE(RSA_MULT_MODE_REG, (num_words / 16) - 1); + DPORT_REG_WRITE(RSA_MULT_MODE_REG, (hw_words / 16) - 1); /* Execute first stage montgomery multiplication */ start_op(RSA_MULT_START_REG); @@ -321,7 +330,7 @@ int esp_mpi_mul_mpi_mod(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi wait_op_complete(RSA_MULT_START_REG); /* execute second stage */ - ret = modular_multiply_finish(Z, X, Y, num_words); + ret = modular_multiply_finish(Z, X, Y, hw_words, z_words); esp_mpi_release_hardware(); @@ -343,31 +352,20 @@ int esp_mpi_mul_mpi_mod(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi int mbedtls_mpi_exp_mod( mbedtls_mpi* Z, const mbedtls_mpi* X, const mbedtls_mpi* Y, const mbedtls_mpi* M, mbedtls_mpi* _Rinv ) { int ret = 0; - size_t z_words = hardware_words_needed(Z); - size_t x_words = hardware_words_needed(X); - size_t y_words = hardware_words_needed(Y); - size_t m_words = hardware_words_needed(M); - size_t num_words; + size_t x_words = word_length(X); + size_t y_words = word_length(Y); + size_t m_words = word_length(M); + + /* "all numbers must be the same length", so choose longest number + as cardinal length of operation... + */ + size_t hw_words = hardware_words(MAX(m_words, MAX(x_words, y_words))); mbedtls_mpi Rinv_new; /* used if _Rinv == NULL */ mbedtls_mpi *Rinv; /* points to _Rinv (if not NULL) othwerwise &RR_new */ mbedtls_mpi_uint Mprime; - /* "all numbers must be the same length", so choose longest number - as cardinal length of operation... - */ - num_words = z_words; - if (x_words > num_words) { - num_words = x_words; - } - if (y_words > num_words) { - num_words = y_words; - } - if (m_words > num_words) { - num_words = m_words; - } - - if (num_words * 32 > 4096) { + if (hw_words * 32 > 4096) { return MBEDTLS_ERR_MPI_NOT_ACCEPTABLE; } @@ -380,30 +378,31 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi* Z, const mbedtls_mpi* X, const mbedtls_mpi Rinv = _Rinv; } if (Rinv->p == NULL) { - MBEDTLS_MPI_CHK(calculate_rinv(Rinv, M, num_words)); + MBEDTLS_MPI_CHK(calculate_rinv(Rinv, M, hw_words)); } Mprime = modular_inverse(M); esp_mpi_acquire_hardware(); - /* (As the following are all writes to DPORT memory, no DPORT_STALL_OTHER_CPU_START is required.) */ - /* "mode" register loaded with number of 512-bit blocks, minus 1 */ - DPORT_REG_WRITE(RSA_MODEXP_MODE_REG, (num_words / 16) - 1); + DPORT_REG_WRITE(RSA_MODEXP_MODE_REG, (hw_words / 16) - 1); /* Load M, X, Rinv, M-prime (M-prime is mod 2^32) */ - mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, num_words); - mpi_to_mem_block(RSA_MEM_Y_BLOCK_BASE, Y, num_words); - mpi_to_mem_block(RSA_MEM_M_BLOCK_BASE, M, num_words); - mpi_to_mem_block(RSA_MEM_RB_BLOCK_BASE, Rinv, num_words); + mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, hw_words); + mpi_to_mem_block(RSA_MEM_Y_BLOCK_BASE, Y, hw_words); + mpi_to_mem_block(RSA_MEM_M_BLOCK_BASE, M, hw_words); + mpi_to_mem_block(RSA_MEM_RB_BLOCK_BASE, Rinv, hw_words); DPORT_REG_WRITE(RSA_M_DASH_REG, Mprime); start_op(RSA_START_MODEXP_REG); + /* X ^ Y may actually be shorter than M, but unlikely when used for crypto */ + MBEDTLS_MPI_CHK( mbedtls_mpi_grow(Z, m_words) ); + wait_op_complete(RSA_START_MODEXP_REG); - ret = mem_block_to_mpi(Z, RSA_MEM_Z_BLOCK_BASE, num_words); + mem_block_to_mpi(Z, RSA_MEM_Z_BLOCK_BASE, m_words); esp_mpi_release_hardware(); cleanup: @@ -417,55 +416,56 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi* Z, const mbedtls_mpi* X, const mbedtls_mpi #endif /* MBEDTLS_MPI_EXP_MOD_ALT */ /* Second & final step of a modular multiply - load second multiplication - * factor Y, run the multiply, read back the result into Z. + * factor Y, run the operation (modular inverse), read back the result + * into Z. * * Called from both mbedtls_mpi_exp_mod and mbedtls_mpi_mod_mpi. * * @param Z result value * @param X first multiplication factor (used to set sign of result). * @param Y second multiplication factor. - * @param num_words size of modulo operation, in words (limbs). - * Should already be rounded up to a multiple of 16 words (512 bits) & range checked. + * @param hw_words Size of the hardware operation, in words + * @param z_words Size of the expected result, in words (may be less than hw_words). + * Z will be grown to at least this length. * * Caller must have already called esp_mpi_acquire_hardware(). */ -static int modular_multiply_finish(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t num_words) +static int modular_multiply_finish(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t hw_words, size_t z_words) { int ret = 0; /* Load Y to X input memory block, rerun */ - mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, Y, num_words); + mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, Y, hw_words); start_op(RSA_MULT_START_REG); + MBEDTLS_MPI_CHK( mbedtls_mpi_grow(Z, z_words) ); + wait_op_complete(RSA_MULT_START_REG); - /* Read result into Z */ - ret = mem_block_to_mpi(Z, RSA_MEM_Z_BLOCK_BASE, num_words); + mem_block_to_mpi(Z, RSA_MEM_Z_BLOCK_BASE, z_words); Z->s = X->s * Y->s; + cleanup: 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 num_words); -static int mpi_mult_mpi_overlong(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t Y_bits, size_t words_result); +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_bits, 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 bits_x, bits_y, words_x, words_y, words_mult, words_z; - - /* Count words needed for X & Y in hardware */ - bits_x = mbedtls_mpi_bitlen(X); - bits_y = mbedtls_mpi_bitlen(Y); - /* Convert bit counts to words, rounded up to 512-bit - (16 word) blocks */ - words_x = bits_to_hardware_words(bits_x); - words_y = bits_to_hardware_words(bits_y); + 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 = hardware_words(MAX(x_words, y_words)); // length of one operand in hardware /* Short-circuit eval if either argument is 0 or 1. @@ -473,31 +473,22 @@ int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi argument will sometimes call in here when one argument is too large for the hardware unit, but the other argument is zero or one. - - This leaks some timing information, although overall there is a - lot less timing variation than a software MPI approach. */ - if (bits_x == 0 || bits_y == 0) { + if (x_bits == 0 || y_bits == 0) { mbedtls_mpi_lset(Z, 0); return 0; } - if (bits_x == 1) { + if (x_bits == 1) { ret = mbedtls_mpi_copy(Z, Y); Z->s *= X->s; return ret; } - if (bits_y == 1) { + if (y_bits == 1) { ret = mbedtls_mpi_copy(Z, X); Z->s *= Y->s; return ret; } - words_mult = (words_x > words_y ? words_x : words_y); - - /* Result Z has to have room for double the larger factor */ - words_z = words_mult * 2; - - /* 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.) @@ -505,21 +496,19 @@ int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi 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 (words_mult * 32 > 2048) { - /* Calculate new length of Z */ - words_z = bits_to_hardware_words(bits_x + bits_y); - if (words_z * 32 <= 4096) { + if (hw_words * 32 > 2048) { + if (z_words * 32 <= 4096) { /* 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, words_z); + return mpi_mult_mpi_failover_mod_mult(Z, X, Y, z_words); } else { /* Still too long for the hardware unit... */ - if(bits_y > bits_x) { - return mpi_mult_mpi_overlong(Z, X, Y, bits_y, words_z); + 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, bits_x, words_z); + return mpi_mult_mpi_overlong(Z, Y, X, x_words, z_words); } } } @@ -529,8 +518,8 @@ int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi esp_mpi_acquire_hardware(); /* Copy X (right-extended) & Y (left-extended) to memory block */ - mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, words_mult); - mpi_to_mem_block(RSA_MEM_Z_BLOCK_BASE + words_mult * 4, Y, words_mult); + mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, hw_words); + mpi_to_mem_block(RSA_MEM_Z_BLOCK_BASE + hw_words * 4, Y, hw_words); /* NB: as Y is left-extended, we don't zero the bottom words_mult words of Y block. This is OK for now because zeroing is done by hardware when we do esp_mpi_acquire_hardware(). */ @@ -540,17 +529,20 @@ int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi /* "mode" register loaded with number of 512-bit blocks in result, plus 7 (for range 9-12). (this is ((N~ / 32) - 1) + 8)) */ - DPORT_REG_WRITE(RSA_MULT_MODE_REG, (words_z / 16) + 7); + DPORT_REG_WRITE(RSA_MULT_MODE_REG, ((hw_words * 2) / 16) + 7); start_op(RSA_MULT_START_REG); + MBEDTLS_MPI_CHK( mbedtls_mpi_grow(Z, z_words) ); + wait_op_complete(RSA_MULT_START_REG); /* Read back the result */ - ret = mem_block_to_mpi(Z, RSA_MEM_Z_BLOCK_BASE, words_z); + mem_block_to_mpi(Z, RSA_MEM_Z_BLOCK_BASE, z_words); Z->s = X->s * Y->s; + cleanup: esp_mpi_release_hardware(); return ret; @@ -560,7 +552,7 @@ int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi 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 (A bits + B bits) must still be less than 4096 bits. + Result (z_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: @@ -573,29 +565,30 @@ int mbedtls_mpi_mul_mpi( mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi (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 num_words) +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 = 0; + size_t hw_words = hardware_words(z_words); /* Load coefficients to hardware */ esp_mpi_acquire_hardware(); /* M = 2^num_words - 1, so block is entirely FF */ - for(int i = 0; i < num_words; i++) { + for(int i = 0; i < hw_words; i++) { DPORT_REG_WRITE(RSA_MEM_M_BLOCK_BASE + i * 4, UINT32_MAX); } /* Mprime = 1 */ DPORT_REG_WRITE(RSA_M_DASH_REG, 1); /* "mode" register loaded with number of 512-bit blocks, minus 1 */ - DPORT_REG_WRITE(RSA_MULT_MODE_REG, (num_words / 16) - 1); + DPORT_REG_WRITE(RSA_MULT_MODE_REG, (hw_words / 16) - 1); /* Load X */ - mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, num_words); + mpi_to_mem_block(RSA_MEM_X_BLOCK_BASE, X, hw_words); /* Rinv = 1 */ DPORT_REG_WRITE(RSA_MEM_RB_BLOCK_BASE, 1); - for(int i = 1; i < num_words; i++) { + for(int i = 1; i < hw_words; i++) { DPORT_REG_WRITE(RSA_MEM_RB_BLOCK_BASE + i * 4, 0); } @@ -604,7 +597,7 @@ static int mpi_mult_mpi_failover_mod_mult(mbedtls_mpi *Z, const mbedtls_mpi *X, wait_op_complete(RSA_MULT_START_REG); /* finish the modular multiplication */ - ret = modular_multiply_finish(Z, X, Y, num_words); + ret = modular_multiply_finish(Z, X, Y, hw_words, z_words); esp_mpi_release_hardware(); @@ -628,29 +621,28 @@ static int mpi_mult_mpi_failover_mod_mult(mbedtls_mpi *Z, const mbedtls_mpi *X, 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 bits_y, size_t words_result) +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; - const size_t limbs_y = (bits_y + biL - 1) / biL; /* Rather than slicing in two on bits we slice on limbs (32 bit words) */ - const size_t limbs_slice = limbs_y / 2; + 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 = { .p = Y->p, - .n = limbs_slice, + .n = words_slice, .s = Y->s }; /* Ypp holds upper bits of Y, right shifted (also reuses Y's array contents) */ const mbedtls_mpi Ypp = { - .p = Y->p + limbs_slice, - .n = limbs_y - limbs_slice, + .p = Y->p + words_slice, + .n = y_words - words_slice, .s = Y->s }; mbedtls_mpi_init(&Ztemp); /* Grow Z to result size early, avoid interim allocations */ - mbedtls_mpi_grow(Z, words_result); + mbedtls_mpi_grow(Z, z_words); /* Get result Ztemp = Yp * X (need temporary variable Ztemp) */ MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi(&Ztemp, X, &Yp) ); @@ -659,7 +651,7 @@ static int mpi_mult_mpi_overlong(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbe MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi(Z, X, &Ypp) ); /* Z = Z << b */ - MBEDTLS_MPI_CHK( mbedtls_mpi_shift_l(Z, limbs_slice * biL) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_shift_l(Z, words_slice * 32) ); /* Z += Ztemp */ MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi(Z, Z, &Ztemp) ); diff --git a/components/mbedtls/test/test_ecp.c b/components/mbedtls/test/test_ecp.c new file mode 100644 index 000000000..0c8f571db --- /dev/null +++ b/components/mbedtls/test/test_ecp.c @@ -0,0 +1,77 @@ +/* mbedTLS Elliptic Curve functionality tests + + Focus on testing functionality where we use ESP32 hardware + accelerated crypto features. + +*/ +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include "unity.h" + +/* Note: negative value here so that assert message prints a grep-able + error hex value (mbedTLS uses -N for error codes) */ +#define TEST_ASSERT_MBEDTLS_OK(X) TEST_ASSERT_EQUAL_HEX32(0, -(X)) + +TEST_CASE("mbedtls ECDH Generate Key", "[mbedtls]") +{ + mbedtls_ecdh_context ctx; + mbedtls_entropy_context entropy; + mbedtls_ctr_drbg_context ctr_drbg; + + mbedtls_ecdh_init(&ctx); + mbedtls_ctr_drbg_init(&ctr_drbg); + + mbedtls_entropy_init(&entropy); + TEST_ASSERT_MBEDTLS_OK( mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0) ); + + TEST_ASSERT_MBEDTLS_OK( mbedtls_ecp_group_load(&ctx.grp, MBEDTLS_ECP_DP_CURVE25519) ); + + TEST_ASSERT_MBEDTLS_OK( mbedtls_ecdh_gen_public(&ctx.grp, &ctx.d, &ctx.Q, + mbedtls_ctr_drbg_random, &ctr_drbg ) ); + + mbedtls_ecdh_free(&ctx); + mbedtls_ctr_drbg_free(&ctr_drbg); + mbedtls_entropy_free(&entropy); +} + +TEST_CASE("mbedtls ECP self-tests", "[mbedtls]") +{ + TEST_ASSERT_EQUAL(0, mbedtls_ecp_self_test(1)); +} + +TEST_CASE("mbedtls ECP mul w/ koblitz", "[mbedtls]") +{ + /* Test case code via https://github.com/espressif/esp-idf/issues/1556 */ + mbedtls_entropy_context ctxEntropy; + mbedtls_ctr_drbg_context ctxRandom; + mbedtls_ecdsa_context ctxECDSA; + const char* pers = "myecdsa"; + + mbedtls_entropy_init(&ctxEntropy); + mbedtls_ctr_drbg_init(&ctxRandom); + TEST_ASSERT_MBEDTLS_OK( mbedtls_ctr_drbg_seed(&ctxRandom, mbedtls_entropy_func, &ctxEntropy, + (const unsigned char*) pers, strlen(pers)) ); + + mbedtls_ecdsa_init(&ctxECDSA); + + TEST_ASSERT_MBEDTLS_OK( mbedtls_ecdsa_genkey(&ctxECDSA, MBEDTLS_ECP_DP_SECP256K1, + mbedtls_ctr_drbg_random, &ctxRandom) ); + + + TEST_ASSERT_MBEDTLS_OK(mbedtls_ecp_mul(&ctxECDSA.grp, &ctxECDSA.Q, &ctxECDSA.d, &ctxECDSA.grp.G, + mbedtls_ctr_drbg_random, &ctxRandom) ); + + mbedtls_ecdsa_free(&ctxECDSA); + mbedtls_ctr_drbg_free(&ctxRandom); + mbedtls_entropy_free(&ctxEntropy); +} +