feat: add zeroize feature

Cargo.toml

@@ -44,15 +44,16 @@ version = "0.5"
 default-features = false
 features = ["std"]
 
+[dependencies.zeroize]
+version = "0.5"
+optional = true
+
 [dependencies.serde]
 optional = true
 version = "1.0"
 default-features = false
 features = ["std"]
 
-[dev-dependencies.serde_test]
-version = "1.0"
-
 [dependencies.lazy_static]
 version = "1.2.0"
 
@@ -63,9 +64,12 @@ version = "1.2.7"
 criterion = "0.2"
 rand_chacha = "0.1"
 
+[dev-dependencies.serde_test]
+version = "1.0"
+
 [features]
 default = ["std", "i128", "u64_digit"]
 i128 = ["num-integer/i128", "num-traits/i128"]
 std = ["num-integer/std", "num-traits/std", "smallvec/std"]
 u64_digit = []
-prime = ["rand"]
+prime = ["rand"]

src/bigint.rs

@@ -17,6 +17,9 @@ use std::{i64, u64};
 #[cfg(feature = "serde")]
 use serde;
 
+#[cfg(feature = "zeroize")]
+use zeroize::Zeroize;
+
 use integer::{Integer, Roots};
 use num_traits::{
     CheckedAdd, CheckedDiv, CheckedMul, CheckedSub, FromPrimitive, Num, One, Pow, Signed,
@@ -119,6 +122,15 @@ pub struct BigInt {
     pub(crate) data: BigUint,
 }
 
+#[cfg(feature = "zeroize")]
+impl Zeroize for BigInt {
+    fn zeroize(&mut self) {
+        // TODO: Figure out how to better clear the sign.
+        self.sign = Sign::NoSign;
+        self.data.zeroize();
+    }
+}
+
 /// Return the magnitude of a `BigInt`.
 ///
 /// This is in a private module, pseudo pub(crate)

src/biguint.rs

@@ -18,6 +18,9 @@ use std::{u64, u8};
 #[cfg(feature = "serde")]
 use serde;
 
+#[cfg(feature = "zeroize")]
+use zeroize::Zeroize;
+
 use integer::{Integer, Roots};
 use num_traits::{
     CheckedAdd, CheckedDiv, CheckedMul, CheckedSub, Float, FromPrimitive, Num, One, Pow,
@@ -50,6 +53,13 @@ pub struct BigUint {
     pub(crate) data: SmallVec<[BigDigit; VEC_SIZE]>,
 }
 
+#[cfg(feature = "zeroize")]
+impl Zeroize for BigUint {
+    fn zeroize(&mut self) {
+        self.data.zeroize();
+    }
+}
+
 impl PartialEq for BigUint {
     #[inline]
     fn eq(&self, other: &BigUint) -> bool {

src/lib.rs

@@ -90,6 +90,9 @@ extern crate rand;
 #[cfg(feature = "serde")]
 extern crate serde;
 
+#[cfg(feature = "zeroize")]
+extern crate zeroize;
+
 #[macro_use]
 extern crate smallvec;