python interface for modular exponentiation

Cargo.lock

@@ -115,6 +115,7 @@ name = "plexcryptool"
 version = "0.1.0"
 dependencies = [
  "num-bigint",
+ "num-traits",
  "pyo3",
 ]
 

Cargo.toml

@@ -15,4 +15,5 @@ path = "src/main.rs"
 
 [dependencies]
 num-bigint = "0.4.3"
+num-traits = "0.2.15"
 pyo3 = "0.18.1"

src/lib.rs

@@ -15,6 +15,7 @@ fn register_binary_module(py: Python, parent_module: &PyModule) -> PyResult<()>
 #[pymodule]
 fn register_math_module(py: Python, parent_module: &PyModule) -> PyResult<()> {
     let math_module = PyModule::new(py, "math")?;
+    math_module.add_function(wrap_pyfunction!(modular_exponentiation::py_modular_exponentiation, math_module)?)?;
     parent_module.add_submodule(math_module)?;
     Ok(())
 }

src/modular_exponentiation.rs

@@ -1,6 +1,11 @@
 #![allow(dead_code)]
 
 use num_bigint::BigInt;
+use num_traits::ToPrimitive;
+use num_traits::FromPrimitive;
+use pyo3::exceptions::PyException;
+use pyo3::exceptions::PyValueError;
+use pyo3::prelude::*;
 
 /// works, but is forbidden for class
 pub fn calc_exp_in_field_lib(
@@ -43,6 +48,28 @@ pub fn modular_exponentiation(
     return exp;
 }
 
+#[pyfunction]
+pub fn py_modular_exponentiation(
+    base: i128,
+    orig_exp: i128, 
+    field: i128) -> PyResult<u128> {
+    let big_res = modular_exponentiation(
+        BigInt::from(base), 
+        BigInt::from(orig_exp), 
+        BigInt::from(field)
+        );
+    let res = big_res.to_u128();
+    match res {
+        Some(v) => {
+            return Ok(v);
+        }
+        None => {
+            return Err(PyValueError::new_err("result is too big!"));
+        }
+    }
+
+}
+
 // Vec<u8> to Vec<bool> ( binary representation interpreted otherwise )
 fn bytes_to_bools(bytes: &Vec<u8>) -> Vec<bool> {
     let mut result: Vec<bool> = Vec::new();