support no_std

Cargo.toml

@@ -12,7 +12,9 @@ categories = [ "cryptography" ]
 
 [dependencies]
 cryptoxide = "0.4"
+zeroize = "1.6.0"
 
 [features]
-default = []
-with-bench = []
+default = ["std"]
+std = []
+with-bench = []

rust-toolchain

@@ -0,0 +1 @@
+nightly

src/derivation/mod.rs

@@ -1,3 +1,6 @@
+#[cfg(not(feature = "std"))]
+use core as std;
+
 mod common;
 pub mod v2;
 

src/hex.rs

@@ -1,3 +1,9 @@
+#[cfg(not(feature = "std"))]
+use alloc::string::String;
+
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
+
 const ALPHABET: &'static [u8] = b"0123456789abcdef";
 
 pub fn encode(input: &[u8]) -> String {

src/key.rs

@@ -1,3 +1,6 @@
+#[cfg(not(feature = "std"))]
+use core as std;
+
 use std::fmt;
 
 use cryptoxide::constant_time::CtEqual;

src/lib.rs

@@ -10,12 +10,20 @@
 //! In soft derivation, the important property is that given the parent public key,
 //! one can derive all softly derived children public key.
 
-#![cfg_attr(feature = "with-bench", feature(test))]
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(not(feature = "std"), feature(error_in_core))]
 
+#![cfg_attr(feature = "with-bench", feature(test))]
 #[cfg(test)]
 #[cfg(feature = "with-bench")]
 extern crate test;
 
+#[cfg(not(feature = "std"))]
+extern crate alloc;
+
+#[cfg(not(feature = "std"))]
+extern crate core;
+
 mod derivation;
 mod hex;
 mod key;

src/securemem.rs

@@ -1,9 +1,5 @@
+use zeroize::Zeroize;
+
 pub fn zero(to_zero: &mut [u8]) {
-    // the unsafety of this call is bounded to the existence of the pointer
-    // and the accuracy of the length of the array.
-    //
-    // since to_zero existence is bound to live at least as long as the call
-    // of this function and that we use the length (in bytes) of the given
-    // slice, this call is safe.
-    unsafe { ::std::ptr::write_bytes(to_zero.as_mut_ptr(), 0, to_zero.len()) }
+    to_zero.zeroize()
 }

src/signature.rs

@@ -1,3 +1,6 @@
+#[cfg(not(feature = "std"))]
+use core as std;
+
 use super::hex;
 use std::error::Error;
 use std::fmt;