src/tasks/mod.rs

@@ -9,8 +9,8 @@ use tasks01::{
     gfmul::gfmul_task,
     pad_oracle::padding_oracle,
     pfmath::{
-        gfdiv, gfpoly_add, gfpoly_diff, gfpoly_divmod, gfpoly_make_monic, gfpoly_mul, gfpoly_pow,
-        gfpoly_powmod, gfpoly_sort, gfpoly_sqrt,
+        gfdiv, gfpoly_add, gfpoly_diff, gfpoly_divmod, gfpoly_gcd, gfpoly_make_monic, gfpoly_mul,
+        gfpoly_pow, gfpoly_powmod, gfpoly_sort, gfpoly_sqrt,
     },
     poly2block::poly2block,
     sea128::sea128,
@@ -151,6 +151,12 @@ pub fn task_deploy(testcase: &Testcase) -> Result<Value> {
 
             Ok(json)
         }
+        "gfpoly_gcd" => {
+            let result = gfpoly_gcd(args)?;
+            let json = json!({"G" : result.to_c_array()});
+
+            Ok(json)
+        }
 
         _ => Err(anyhow!(
             "Fatal. No compatible action found. Json data was {:?}. Arguments were; {:?}",

src/tasks/tasks01/pfmath.rs

@@ -2,7 +2,10 @@ use anyhow::Result;
 use base64::{prelude::BASE64_STANDARD, Engine};
 use serde_json::Value;
 
-use crate::utils::{field::FieldElement, poly::Polynomial};
+use crate::utils::{
+    field::FieldElement,
+    poly::{gcd, Polynomial},
+};
 
 pub fn gfpoly_add(args: &Value) -> Result<Polynomial> {
     let poly_a = Polynomial::from_c_array(&args["A"].clone());
@@ -105,6 +108,15 @@ pub fn gfpoly_diff(args: &Value) -> Result<Polynomial> {
     Ok(result)
 }
 
+pub fn gfpoly_gcd(args: &Value) -> Result<Polynomial> {
+    let poly_a = Polynomial::from_c_array(&args["A"].clone());
+    let poly_b = Polynomial::from_c_array(&args["B"].clone());
+
+    let result = gcd(poly_a, poly_b);
+
+    Ok(result)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/utils/poly.rs

@@ -483,6 +483,14 @@ impl Ord for Polynomial {
     }
 }
 
+pub fn gcd(a: Polynomial, b: Polynomial) -> Polynomial {
+    if a.is_zero() {
+        return b;
+    }
+
+    return gcd(b.div(&a).1.monic(), a);
+}
+
 pub fn sort_polynomial_array(mut polys: Vec<Polynomial>) -> Result<Vec<Polynomial>> {
     // Algorithm to sort polynomials
     // First sorting round
@@ -1254,10 +1262,46 @@ mod tests {
         ]);
         let expected = json!(["AAAAAAAAAAAAAAAAAAAAAA==",]);
         let element1: Polynomial = Polynomial::from_c_array(&json1);
-        eprintln!("Starting poly sqrt");
 
         let result = element1.diff();
 
         assert_eq!(json!(result.to_c_array()), expected);
     }
+  
+    #[test]
+    fn test_poly_gcd() {
+        let a = json!([
+            "DNWpXnnY24XecPa7a8vrEA==",
+            "I8uYpCbsiPaVvUznuv1IcA==",
+            "wsbiU432ARWuO93He3vbvA==",
+            "zp0g3o8iNz7Y+8oUxw1vJw==",
+            "J0GekE3uendpN6WUAuJ4AA==",
+            "wACd0e6u1ii4AAAAAAAAAA==",
+            "ACAAAAAAAAAAAAAAAAAAAA=="
+        ]);
+        let b = json!([
+            "I20VjJmlSnRSe88gaDiLRQ==",
+            "0Cw5HxJm/pfybJoQDf7/4w==",
+            "8ByrMMf+vVj5r3YXUNCJ1g==",
+            "rEU/f2UZRXqmZ6V7EPKfBA==",
+            "LfdALhvCrdhhGZWl9l9DSg==",
+            "KSUKhN0n6/DZmHPozd1prw==",
+            "DQrRkuA9Zx279wAAAAAAAA==",
+            "AhCEAAAAAAAAAAAAAAAAAA=="
+        ]);
+        let expected = json!([
+            "NeverGonnaMakeYouCryAA==",
+            "NeverGonnaSayGoodbyeAA==",
+            "NeverGonnaTellALieAAAA==",
+            "AndHurtYouAAAAAAAAAAAA==",
+            "gAAAAAAAAAAAAAAAAAAAAA=="
+        ]);
+
+        let a: Polynomial = Polynomial::from_c_array(&a);
+        let b: Polynomial = Polynomial::from_c_array(&b);
+
+        let result = gcd(a.monic(), b.monic());
+
+        assert_eq!(json!(result.to_c_array()), expected);
+    }
 }

test_json/sandbox.json

@@ -1,13 +1,26 @@
 {
   "testcases": {
     "sandbox": {
-      "action": "gfpoly_diff",
+      "action": "gfpoly_gcd",
       "arguments": {
-        "F": [
-          "IJustWannaTellYouAAAAA==",
-          "HowImFeelingAAAAAAAAAA==",
-          "GottaMakeYouAAAAAAAAAA==",
-          "UnderstaaaaaaaaaaaaanQ=="
+        "A": [
+          "DNWpXnnY24XecPa7a8vrEA==",
+          "I8uYpCbsiPaVvUznuv1IcA==",
+          "wsbiU432ARWuO93He3vbvA==",
+          "zp0g3o8iNz7Y+8oUxw1vJw==",
+          "J0GekE3uendpN6WUAuJ4AA==",
+          "wACd0e6u1ii4AAAAAAAAAA==",
+          "ACAAAAAAAAAAAAAAAAAAAA=="
+        ],
+        "B": [
+          "I20VjJmlSnRSe88gaDiLRQ==",
+          "0Cw5HxJm/pfybJoQDf7/4w==",
+          "8ByrMMf+vVj5r3YXUNCJ1g==",
+          "rEU/f2UZRXqmZ6V7EPKfBA==",
+          "LfdALhvCrdhhGZWl9l9DSg==",
+          "KSUKhN0n6/DZmHPozd1prw==",
+          "DQrRkuA9Zx279wAAAAAAAA==",
+          "AhCEAAAAAAAAAAAAAAAAAA=="
         ]
       }
     }