bignum_common.py: Added `bits_to_limbs` method.
This patch introduces a rounding-error-resiliant method to
calculate bits_to_limbs, and is updating `SECP224R1` and
`SECP224K1` to use it.
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/scripts/mbedtls_dev/ecp.py b/scripts/mbedtls_dev/ecp.py
index 8a3ab28..ed79a07 100644
--- a/scripts/mbedtls_dev/ecp.py
+++ b/scripts/mbedtls_dev/ecp.py
@@ -165,7 +165,8 @@
@property
def arg_a(self) -> str:
- hex_digits = bignum_common.hex_digits_for_limb(448 // self.bits_in_limb, self.bits_in_limb)
+ limbs = 2 * bignum_common.bits_to_limbs(224, self.bits_in_limb)
+ hex_digits = bignum_common.hex_digits_for_limb(limbs, self.bits_in_limb)
return super().format_arg('{:x}'.format(self.int_a)).zfill(hex_digits)
def result(self) -> List[str]:
@@ -624,7 +625,8 @@
@property
def arg_a(self) -> str:
- hex_digits = bignum_common.hex_digits_for_limb(448 // self.bits_in_limb, self.bits_in_limb)
+ limbs = 2 * bignum_common.bits_to_limbs(224, self.bits_in_limb)
+ hex_digits = bignum_common.hex_digits_for_limb(limbs, self.bits_in_limb)
return super().format_arg('{:x}'.format(self.int_a)).zfill(hex_digits)
def result(self) -> List[str]: