src/utils/field.rs

@@ -9,6 +9,8 @@ use std::{
 
 use anyhow::{anyhow, Ok, Result};
 
+use crate::utils::poly::bgfmul;
+
 use super::poly::polynomial_2_block;
 use super::{
     math::{reverse_bits_in_bytevec, xor_bytes},
@@ -22,7 +24,7 @@ pub struct FieldElement {
 
 impl FieldElement {
     pub const IRREDUCIBLE_POLYNOMIAL: [u8; 17] = [
-        87, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 01,
+        0x87, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 0x01,
     ];
 
     pub fn rand() -> Self {
@@ -30,10 +32,14 @@ impl FieldElement {
         FieldElement::new(rand_field.to_vec())
     }
 
-    pub fn zero(self) -> Self {
+    pub fn zero() -> Self {
         FieldElement::new(vec![0])
     }
 
+    pub fn one() -> Self {
+        FieldElement::new(vec![0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+    }
+
     pub const fn new(field_element: Vec<u8>) -> Self {
         Self { field_element }
     }
@@ -47,8 +53,7 @@ impl FieldElement {
     }
 
     pub fn pow(mut self, mut exponent: u128) -> FieldElement {
-        let mut result: FieldElement =
-            FieldElement::new(polynomial_2_block(vec![0], "gcm").unwrap());
+        let mut result: FieldElement = FieldElement::one();
 
         if exponent == 1 {
             eprintln!("special case 1: {:02X?}", self.clone());
@@ -57,7 +62,7 @@ impl FieldElement {
         }
 
         if exponent == 0 {
-            let result = FieldElement::new(polynomial_2_block(vec![0], "gcm").unwrap());
+            let result = FieldElement::one();
 
             eprintln!("Returned value is: {:02X?}", result);
             return result;
@@ -90,8 +95,10 @@ impl FieldElement {
     }
 
     pub fn inv(mut self) -> Self {
-        let mut inverser: u128 = 0xfffffffffffffffffffffffffffffffe;
-        let mut inverse: Vec<u8> = polynomial_2_block(vec![0], "gcm").unwrap();
+        const INVERSER_START: u128 = 0xfffffffffffffffffffffffffffffffe;
+
+        let mut inverser = INVERSER_START;
+        let mut inverse: Vec<u8> = vec![0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
         //eprintln!("Inverse start {:02X?}", inverse);
 
         while inverser > 0 {
@@ -187,7 +194,7 @@ impl Div for FieldElement {
     type Output = Self;
     fn div(self, rhs: Self) -> Self::Output {
         let inverse = rhs.inv();
-        self.clone() * inverse
+        self * inverse
     }
 }
 
@@ -195,10 +202,7 @@ impl Div for &FieldElement {
     type Output = FieldElement;
 
     fn div(self, rhs: Self) -> Self::Output {
-        // First clone and invert the divisor (rhs)
-        let rhs_inv = rhs.clone().inv();
-        // Multiply original number by the inverse
-        self.clone() * rhs_inv
+        self.clone() * rhs.clone().inv()
     }
 }
 

src/utils/poly.rs

@@ -1,6 +1,7 @@
 use crate::utils::field::ByteArray;
 use base64::alphabet::BIN_HEX;
 use base64::prelude::*;
+use num::traits::FromBytes;
 use num::{BigInt, BigUint, One, Zero};
 use std::{str::FromStr, u128, u8, usize};
 
@@ -13,6 +14,7 @@ use anyhow::{anyhow, Ok, Result};
 use serde_json::Value;
 
 use super::field::FieldElement;
+use super::math::reverse_bits_in_bytevec;
 
 #[derive(Debug, serde::Serialize, serde::Deserialize)]
 pub struct Polynomial {
@@ -291,10 +293,7 @@ impl Polynomial {
         }
 
         let mut quotient_coeffs =
-            vec![
-                FieldElement::new(polynomial_2_block(vec![0; 16], "gcm").unwrap());
-                dividend_deg - divisor_deg + 1
-            ];
+            vec![FieldElement::new(vec![0; 16]); dividend_deg - divisor_deg + 1];
 
         while remainder.polynomial.len() >= divisor.polynomial.len() {
             let deg_diff = remainder.polynomial.len() - divisor.polynomial.len();
@@ -305,8 +304,7 @@ impl Polynomial {
 
             quotient_coeffs[deg_diff] = quot_coeff.clone();
 
-            let mut subtrahend =
-                vec![FieldElement::new(polynomial_2_block(vec![0; 16], "gcm").unwrap()); deg_diff];
+            let mut subtrahend = vec![FieldElement::new(vec![0; 16]); deg_diff];
             subtrahend.extend(
                 divisor
                     .polynomial
@@ -658,6 +656,53 @@ pub fn gfmul(poly_a: &Vec<u8>, poly_b: &Vec<u8>, semantic: &str) -> Result<Vec<u
     Ok(result.0)
 }
 
+pub fn bgfmul(poly_a: &Vec<u8>, poly_b: &Vec<u8>, semantic: &str) -> Result<Vec<u8>> {
+    //TODO: Implement gfmul with bigint
+    let red_poly_bytes: BigUint = BigUint::from_slice(&[
+        0x87, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 0x01,
+    ]);
+
+    let mut poly1: BigUint = BigUint::from_le_bytes(&reverse_bits_in_bytevec(poly_a.to_owned()));
+
+    let mut poly2: BigUint = BigUint::from_le_bytes(&reverse_bits_in_bytevec(poly_b.to_owned()));
+
+    /*
+    if semantic == "gcm" {
+        poly1.re;
+        poly2.reverse_bits_in_bytevec();
+    }
+    */
+
+    let mut result: BigUint = BigUint::zero();
+
+    if (&poly2 & (BigUint::one() << 127)) == BigUint::one() {
+        result = &result ^ &poly1;
+    }
+    poly2 = &poly2 >> 1;
+
+    while &poly2 != &BigUint::zero() {
+        poly1 = &poly1 << 1;
+
+        if (&poly1 & (BigUint::one() << 127)) == BigUint::one() {
+            poly1 = &poly1 ^ &red_poly_bytes;
+        }
+
+        if &poly2 & BigUint::one() == BigUint::one() {
+            result = &result ^ &poly1;
+        }
+
+        poly2 = &poly2 >> 1;
+    }
+
+    /*
+        if semantic == "gcm" {
+            result.reverse_bits_in_bytevec();
+        }
+    */
+
+    Ok(reverse_bits_in_bytevec(result.to_bytes_le()))
+}
+
 pub fn convert_gcm_to_xex(gcm_poly: Vec<u8>) -> Result<Vec<u8>> {
     let xex_poly = gcm_poly
         .into_iter()
@@ -795,7 +840,7 @@ pub fn coefficient_to_binary(coefficients: Vec<u8>) -> u128 {
 
 #[cfg(test)]
 mod tests {
-    use crate::utils::poly::b64_2_num;
+    use crate::utils::poly::{b64_2_num, gcd};
     use anyhow::Result;
     use serde_json::json;
     // Note this useful idiom: importing names from outer (for mod tests) scope.
@@ -1429,4 +1474,17 @@ mod tests {
 
         assert_eq!(json!(result.to_c_array()), expected);
     }
+
+    #[test]
+    fn test_poly_gcd_stress() {
+        eprintln!("{:?}", Polynomial::one());
+
+        let poly1 = Polynomial::rand(&(500 as usize));
+        let poly2 = Polynomial::rand(&(500 as usize));
+
+        let result = gcd(&poly1.monic(), &poly2.monic());
+
+        eprintln!("{:02X?}", result.to_c_array());
+        assert!(true);
+    }
 }