From 2e3dcf50bd179b1a888f8b320144429b23bb7ad6 Mon Sep 17 00:00:00 2001
From: trantorian <114066155+Trantorian1@users.noreply.github.com>
Date: Wed, 9 Oct 2024 18:11:26 +0200
Subject: [PATCH] feat(zeroize): added zeorizing to `Felt`

This is feature-gated behind the `zeroing` flag
---
 crates/starknet-types-core/Cargo.toml      |  7 +++++--
 crates/starknet-types-core/src/felt/mod.rs | 22 ++++++++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/crates/starknet-types-core/Cargo.toml b/crates/starknet-types-core/Cargo.toml
index 70946ea..55476ec 100644
--- a/crates/starknet-types-core/Cargo.toml
+++ b/crates/starknet-types-core/Cargo.toml
@@ -24,9 +24,10 @@ serde = { version = "1", optional = true, default-features = false, features = [
 lambdaworks-crypto = { version = "0.10.0", default-features = false, optional = true }
 parity-scale-codec = { version = "3.6", default-features = false, optional = true }
 lazy_static = { version = "1.5", default-features = false, optional = true }
+zeroize = { version = "1.8.1", default-features = false, optional = true }
 
 [features]
-default = ["std", "serde", "curve", "num-traits"]
+default = ["std", "serde", "curve", "num-traits", "zeroing"]
 std = [
   "lambdaworks-math/std",
   "num-traits/std",
@@ -34,8 +35,9 @@ std = [
   "num-integer/std",
   "serde?/std",
   "lambdaworks-crypto?/std",
+  "zeroize?/std",
 ]
-alloc = []
+alloc = ["zeroize?/alloc"]
 curve = []
 hash = ["dep:lambdaworks-crypto"]
 arbitrary = ["std", "dep:arbitrary"]
@@ -44,6 +46,7 @@ serde = ["alloc", "dep:serde"]
 prime-bigint = ["dep:lazy_static"]
 num-traits = []
 papyrus-serialization = ["std"]
+zeroing = ["zeroize"]
 
 [dev-dependencies]
 proptest = "1.5"
diff --git a/crates/starknet-types-core/src/felt/mod.rs b/crates/starknet-types-core/src/felt/mod.rs
index 11d99b9..04b9284 100644
--- a/crates/starknet-types-core/src/felt/mod.rs
+++ b/crates/starknet-types-core/src/felt/mod.rs
@@ -1062,6 +1062,18 @@ mod errors {
     }
 }
 
+mod zeroing {
+    use super::*;
+
+    #[cfg(feature = "zeroing")]
+    impl zeroize::Zeroize for Felt {
+        fn zeroize(&mut self) {
+            core::mem::take(self);
+            core::sync::atomic::compiler_fence(core::sync::atomic::Ordering::SeqCst);
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::alloc::{format, string::String, vec::Vec};
@@ -1844,4 +1856,14 @@ mod test {
             assert_eq!(Felt::from_bytes_be(&bytes), d);
         }
     }
+
+    #[cfg(feature = "zeroing")]
+    #[test]
+    fn zeroing_felt() {
+        use zeroize::Zeroize;
+
+        let mut felt = Felt::from_hex_unchecked("0x01");
+        felt.zeroize();
+        assert_eq!(felt, Felt::ZERO);
+    }
 }