Separate out to_montgomery and from_montgomery for bignum tests

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>

3 files changed, 11 insertions, 6 deletions

diff --git a/scripts/mbedtls_dev/bignum_common.py b/scripts/mbedtls_dev/bignum_common.py
index 67ea78db4..81bc28e19 100644
--- a/scripts/mbedtls_dev/bignum_common.py
+++ b/scripts/mbedtls_dev/bignum_common.py
@@ -251,6 +251,12 @@ class ModOperationCommon(OperationCommon):
         # provides earlier/more robust input validation.
         self.int_n = hex_to_int(val_n)
 
+    def to_montgomery(self, val) -> int:
+        return (val * self.r) % self.int_n
+
+    def from_montgomery(self, val) -> int:
+        return (val * self.r_inv) % self.int_n
+
     @property
     def boundary(self) -> int:
         return self.int_n
diff --git a/scripts/mbedtls_dev/bignum_core.py b/scripts/mbedtls_dev/bignum_core.py
index a000bde07..118a659cf 100644
--- a/scripts/mbedtls_dev/bignum_core.py
+++ b/scripts/mbedtls_dev/bignum_core.py
@@ -764,7 +764,7 @@ class BignumCoreExpMod(BignumCoreTarget, bignum_common.ModOperationCommon):
 
     def arguments(self) -> List[str]:
         # Input 'a' has to be given in Montgomery form
-        mont_a = (self.int_a * self.r) % self.int_n
+        mont_a = self.to_montgomery(self.int_a)
         arg_mont_a = self.format_arg('{:x}'.format(mont_a))
         return [bignum_common.quote_str(n) for n in [self.arg_n,
                                                      arg_mont_a,
@@ -772,9 +772,9 @@ class BignumCoreExpMod(BignumCoreTarget, bignum_common.ModOperationCommon):
                ] + self.result()
 
     def result(self) -> List[str]:
-        # Result has to be given in Montgomery form
+        # Result has to be given in Montgomery form too
         result = pow(self.int_a, self.int_b, self.int_n)
-        mont_result = (result * self.r) % self.int_n
+        mont_result = self.to_montgomery(result)
         return [self.format_result(mont_result)]
 
     @property
diff --git a/scripts/mbedtls_dev/bignum_mod_raw.py b/scripts/mbedtls_dev/bignum_mod_raw.py
index 0bbad5dd9..d05479a00 100644
--- a/scripts/mbedtls_dev/bignum_mod_raw.py
+++ b/scripts/mbedtls_dev/bignum_mod_raw.py
@@ -92,10 +92,9 @@ class BignumModRawConvertToMont(bignum_common.ModOperationCommon,
     arity = 1
 
     def result(self) -> List[str]:
-        result = (self.int_a * self.r) % self.int_n
+        result = self.to_montgomery(self.int_a)
         return [self.format_result(result)]
 
-
 class BignumModRawConvertFromMont(bignum_common.ModOperationCommon,
                                   BignumModRawTarget):
     """ Test cases for mpi_mod_raw_from_mont_rep(). """
@@ -106,7 +105,7 @@ class BignumModRawConvertFromMont(bignum_common.ModOperationCommon,
     arity = 1
 
     def result(self) -> List[str]:
-        result = (self.int_a * self.r_inv) % self.int_n
+        result = self.from_montgomery(self.int_a)
         return [self.format_result(result)]