diff --git a/library/bignum_core.c b/library/bignum_core.c index b0ffa37d3c..de57cfc04c 100644 --- a/library/bignum_core.c +++ b/library/bignum_core.c @@ -366,6 +366,41 @@ void mbedtls_mpi_core_shift_r(mbedtls_mpi_uint *X, size_t limbs, } } +void mbedtls_mpi_core_shift_l(mbedtls_mpi_uint *X, size_t limbs, + size_t count) +{ + size_t i, v0, v1; + mbedtls_mpi_uint r0 = 0, r1; + + v0 = count / (biL); + v1 = count & (biL - 1); + + /* + * shift by count / limb_size + */ + if (v0 > 0) { + for (i = limbs; i > v0; i--) { + X[i - 1] = X[i - v0 - 1]; + } + + for (; i > 0; i--) { + X[i - 1] = 0; + } + } + + /* + * shift by count % limb_size + */ + if (v1 > 0) { + for (i = v0; i < limbs; i++) { + r1 = X[i] >> (biL - v1); + X[i] <<= v1; + X[i] |= r0; + r0 = r1; + } + } +} + mbedtls_mpi_uint mbedtls_mpi_core_add(mbedtls_mpi_uint *X, const mbedtls_mpi_uint *A, const mbedtls_mpi_uint *B, diff --git a/library/bignum_core.h b/library/bignum_core.h index 158d2b3222..21a5a11c6a 100644 --- a/library/bignum_core.h +++ b/library/bignum_core.h @@ -281,7 +281,7 @@ int mbedtls_mpi_core_write_be(const mbedtls_mpi_uint *A, unsigned char *output, size_t output_length); -/** \brief Shift an MPI right in place by a number of bits. +/** \brief Shift an MPI in-place right by a number of bits. * * Shifting by more bits than there are bit positions * in \p X is valid and results in setting \p X to 0. @@ -296,6 +296,21 @@ int mbedtls_mpi_core_write_be(const mbedtls_mpi_uint *A, void mbedtls_mpi_core_shift_r(mbedtls_mpi_uint *X, size_t limbs, size_t count); +/** + * \brief Shift an MPI in-place left by a number of bits. + * + * Shifting by more bits than there are bit positions + * in \p X will produce an unspecified result. + * + * This function's execution time depends on the value + * of \p count (and of course \p limbs). + * \param[in,out] X The number to shift. + * \param limbs The number of limbs of \p X. This must be at least 1. + * \param count The number of bits to shift by. + */ +void mbedtls_mpi_core_shift_l(mbedtls_mpi_uint *X, size_t limbs, + size_t count); + /** * \brief Add two fixed-size large unsigned integers, returning the carry. * diff --git a/scripts/mbedtls_dev/bignum_common.py b/scripts/mbedtls_dev/bignum_common.py index d8ef4a84f5..51b25a3715 100644 --- a/scripts/mbedtls_dev/bignum_common.py +++ b/scripts/mbedtls_dev/bignum_common.py @@ -80,6 +80,23 @@ def hex_digits_for_limb(limbs: int, bits_in_limb: int) -> int: """ Retrun the hex digits need for a number of limbs. """ return 2 * (limbs * bits_in_limb // 8) +def hex_digits_max_int(val: str, bits_in_limb: int) -> int: + """ Return the first number exceeding maximum the limb space + required to store the input hex-string value. This method + weights on the input str_len rather than numerical value + and works with zero-padded inputs""" + n = ((1 << (len(val) * 4)) - 1) + l = limbs_mpi(n, bits_in_limb) + return bound_mpi_limbs(l, bits_in_limb) + +def zfill_match(reference: str, target: str) -> str: + """ Zero pad target hex-string to match the limb size of + the reference input """ + lt = len(target) + lr = len(reference) + target_len = lr if lt < lr else lt + return "{:x}".format(int(target, 16)).zfill(target_len) + class OperationCommon(test_data_generation.BaseTest): """Common features for bignum binary operations. diff --git a/scripts/mbedtls_dev/bignum_core.py b/scripts/mbedtls_dev/bignum_core.py index 5801caef59..ff3fd23e68 100644 --- a/scripts/mbedtls_dev/bignum_core.py +++ b/scripts/mbedtls_dev/bignum_core.py @@ -68,6 +68,68 @@ class BignumCoreShiftR(BignumCoreTarget, test_data_generation.BaseTest): for count in counts: yield cls(input_hex, descr, count).create_test_case() + +class BignumCoreShiftL(BignumCoreTarget, bignum_common.ModOperationCommon): + """Test cases for mbedtls_bignum_core_shift_l().""" + + BIT_SHIFT_VALUES = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', + '1f', '20', '21', '3f', '40', '41', '47', '48', '4f', + '50', '51', '58', '80', '81', '88'] + DATA = ["0", "1", "40", "dee5ca1a7ef10a75", "a1055eb0bb1efa1150ff", + "002e7ab0070ad57001", "020100000000000000001011121314151617", + "1946e2958a85d8863ae21f4904fcc49478412534ed53eaf321f63f2a222" + "7a3c63acbf50b6305595f90cfa8327f6db80d986fe96080bcbb5df1bdbe" + "9b74fb8dedf2bddb3f8215b54dffd66409323bcc473e45a8fe9d08e77a51" + "1698b5dad0416305db7fcf"] + arity = 1 + test_function = "mpi_core_shift_l" + test_name = "Core shift(L)" + input_style = "arch_split" + symbol = "<<" + input_values = BIT_SHIFT_VALUES + moduli = DATA + + @property + def val_n_max_limbs(self) -> int: + """ Return the limb count required to store the maximum number that can + fit in a the number of digits used by val_n """ + m = bignum_common.hex_digits_max_int(self.val_n, self.bits_in_limb) - 1 + return bignum_common.limbs_mpi(m, self.bits_in_limb) + + def arguments(self) -> List[str]: + return [bignum_common.quote_str(self.val_n), + str(self.int_a) + ] + self.result() + + def description(self) -> str: + """ Format the output as: + #{count} {hex input} ({input bits} {limbs capacity}) << {bit shift} """ + bits = "({} bits in {} limbs)".format(self.int_n.bit_length(), self.val_n_max_limbs) + return "{} #{} {} {} {} {}".format(self.test_name, + self.count, + self.val_n, + bits, + self.symbol, + self.int_a) + + def format_result(self, res: int) -> str: + # Override to match zero-pading for leading digits between the output and input. + res_str = bignum_common.zfill_match(self.val_n, "{:x}".format(res)) + return bignum_common.quote_str(res_str) + + def result(self) -> List[str]: + result = (self.int_n << self.int_a) + # Calculate if there is space for shifting to the left(leading zero limbs) + mx = bignum_common.hex_digits_max_int(self.val_n, self.bits_in_limb) + # If there are empty limbs ahead, adjust the bitmask accordingly + result = result & (mx - 1) + return [self.format_result(result)] + + @property + def is_valid(self) -> bool: + return True + + class BignumCoreCTLookup(BignumCoreTarget, test_data_generation.BaseTest): """Test cases for mbedtls_mpi_core_ct_uint_table_lookup().""" test_function = "mpi_core_ct_uint_table_lookup" diff --git a/tests/suites/test_suite_bignum_core.function b/tests/suites/test_suite_bignum_core.function index 53aa002ce6..81a3a45317 100644 --- a/tests/suites/test_suite_bignum_core.function +++ b/tests/suites/test_suite_bignum_core.function @@ -562,6 +562,26 @@ exit: } /* END_CASE */ +/* BEGIN_CASE */ +void mpi_core_shift_l(char *input, int count, char *result) +{ + mbedtls_mpi_uint *X = NULL; + mbedtls_mpi_uint *Y = NULL; + size_t limbs, n; + + TEST_EQUAL(0, mbedtls_test_read_mpi_core(&X, &limbs, input)); + TEST_EQUAL(0, mbedtls_test_read_mpi_core(&Y, &n, result)); + TEST_EQUAL(limbs, n); + + mbedtls_mpi_core_shift_l(X, limbs, count); + ASSERT_COMPARE(X, limbs * ciL, Y, limbs * ciL); + +exit: + mbedtls_free(X); + mbedtls_free(Y); +} +/* END_CASE */ + /* BEGIN_CASE */ void mpi_core_add_and_add_if(char *input_A, char *input_B, char *input_S, int carry)