attempt to clean up some dependency issues

.cargo/config

@@ -1,2 +1,2 @@
-[build]
-target="x86_64-unknown-linux-gnu"
+#[build]
+#target="x86_64-unknown-linux-gnu"

Cargo.toml

@@ -50,7 +50,6 @@ serde = { version = "1.0", default-features = false, optional = true, features =
 # https://github.com/rust-lang/packed_simd/issues/303#issuecomment-701361161
 packed_simd = { version = "0.3.4", package = "packed_simd_2", features = ["into_bits"], optional = true }
 zeroize = { version = "1", default-features = false }
-rand = { version = "0.7", default-features = false, features = [] }
 fiat-crypto = { version = "0.1.6", optional = true}
 
 # 1. eliminate xous-engine-25519 crate
@@ -61,7 +60,9 @@ fiat-crypto = { version = "0.1.6", optional = true}
 # 6. test that cargo test still works in `std`
 
 # Betrusted/Precursor dependency set
-engine-25519 = {version = "0.1.0", optional = true}
+#[dependencies.engine-25519]
+#version = "0.1.0"
+#optional = true
 [dependencies.engine25519-as]
 #git="https://github.com/betrusted-io/engine25519-as.git"
 #rev="0bafc1ff8f58b66189d8c2f9ab7046cbbef77e6e"
@@ -70,6 +71,11 @@ default-features = false
 features = []
 optional = true
 
+[dev-dependencies.engine25519-as]
+#git="https://github.com/betrusted-io/engine25519-as.git"
+#rev="0bafc1ff8f58b66189d8c2f9ab7046cbbef77e6e"
+path="../engine25519-as"
+
 [features]
 nightly = ["subtle/nightly"]
 default = ["std", "u32_backend"]
@@ -90,6 +96,6 @@ simd_backend = ["nightly", "u64_backend", "packed_simd"]
 # in some future release.
 avx2_backend = ["simd_backend"]
 # the betrusted backend uses the curve25519 hardware accelerator in betrusted-soc
-betrusted = ["engine-25519", "engine25519-as"]
+#betrusted = ["engine-25519", "engine25519-as"]
 
 [workspace]

src/field.rs

@@ -291,6 +291,9 @@ impl FieldElement {
     }
 }
 
+#[cfg(test)]
+extern crate rand;
+
 #[cfg(test)]
 mod test {
     use field::*;
@@ -480,7 +483,7 @@ mod test {
         use std::io::prelude::*;
         use std::path::Path;
         use engine25519_as::*;
-        use rand::Rng;
+        use self::rand::Rng;
 
         fn write_helper(file: &mut File, elem: FieldElement) {
             let elem_bytes = elem.to_bytes();
@@ -1051,7 +1054,9 @@ mod test {
                 write_helper(&mut file, qu);
                 write_helper(&mut file, qw);
                 write_helper(&mut file, pmq);
+                #[allow(non_snake_case)]
                 let mut P: ProjectivePoint = ProjectivePoint{U:pu, W:pw};
+                #[allow(non_snake_case)]
                 let mut Q: ProjectivePoint = ProjectivePoint{U:qu, W:qw};
                 differential_add_and_double(&mut P, &mut Q, &pmq);
                 write_helper(&mut file, &(&P.U + &P.W) + &(&Q.U + &Q.W));
@@ -1253,7 +1258,7 @@ mod test {
             write_helper(&mut file, x1.U);
             write_helper(&mut file, x1.W);
             write_helper(&mut file, affine_u);
-            file.write(&scalar.bytes);
+            file.write(&scalar.bytes).unwrap();
             let number254 = FieldElement::from_bytes(&[
                  254, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

src/lib.rs

@@ -64,9 +64,10 @@ extern crate serde;
 #[macro_use]
 pub(crate) mod macros;
 
+#[cfg(any(feature = "betrusted", test))]
 #[macro_use]
 extern crate engine25519_as;
-extern crate rand;
+#[cfg(feature = "betrusted")]
 extern crate engine_25519;
 
 //------------------------------------------------------------------------

src/montgomery.rs

@@ -64,8 +64,6 @@ use subtle::{ConditionallyNegatable, ConditionallySelectable};
 
 use zeroize::Zeroize;
 
-#[macro_use]
-use engine25519_as;
 
 /// Holds the \\(u\\)-coordinate of a point on the Montgomery form of
 /// Curve25519 or its twist.
@@ -293,6 +291,7 @@ pub fn differential_add_and_double(
     Q.W = t17;  // W_{Q'} = U_D * 4 (W_P U_Q - U_P W_Q)^2
 }
 
+#[cfg(betrusted)]
 fn copy_to_rf(bytes: [u8; 32], register: usize, rf: &mut [u32; engine_25519::RF_SIZE_IN_U32]) {
     use core::convert::TryInto;
     for (byte, rf_dst) in bytes.chunks_exact(4).zip(rf[register * 8..(register+1)*8].iter_mut()) {
@@ -300,6 +299,7 @@ fn copy_to_rf(bytes: [u8; 32], register: usize, rf: &mut [u32; engine_25519::RF_
     }
 }
 
+#[cfg(betrusted)]
 fn copy_from_rf(register: usize, rf: &[u32; engine_25519::RF_SIZE_IN_U32]) -> [u8; 32] {
     let mut ret: [u8; 32] = [0; 32];
 
@@ -312,6 +312,7 @@ fn copy_from_rf(register: usize, rf: &[u32; engine_25519::RF_SIZE_IN_U32]) -> [u
     ret
 }
 
+#[cfg(betrusted)]
 pub fn differential_add_and_double_hw(
     P: &mut ProjectivePoint,
     Q: &mut ProjectivePoint,
@@ -443,11 +444,12 @@ impl<'a, 'b> Mul<&'b Scalar> for &'a MontgomeryPoint {
     type Output = MontgomeryPoint;
 
     /// Given `self` \\( = u\_0(P) \\), and a `Scalar` \\(n\\), return \\( u\_0([n]P) \\).
+    #[cfg(betrusted)]
     fn mul(self, scalar: &'b Scalar) -> MontgomeryPoint {
         // Algorithm 8 of Costello-Smith 2017
         let affine_u = FieldElement::from_bytes(&self.0);
         let mut x0 = ProjectivePoint::identity();
-        let mut x1 = ProjectivePoint {
+        let x1 = ProjectivePoint {
             U: affine_u,
             W: FieldElement::one(),
         };
@@ -631,7 +633,7 @@ impl<'a, 'b> Mul<&'b Scalar> for &'a MontgomeryPoint {
         // curve25519 acceleration!
         x0.to_affine()
     }
-    /*
+    #[cfg(not(betrusted))]
     fn mul(self, scalar: &'b Scalar) -> MontgomeryPoint {
         // Algorithm 8 of Costello-Smith 2017
         let affine_u = FieldElement::from_bytes(&self.0);
@@ -654,7 +656,7 @@ impl<'a, 'b> Mul<&'b Scalar> for &'a MontgomeryPoint {
         ProjectivePoint::conditional_swap(&mut x0, &mut x1, Choice::from(bits[0] as u8));
 
         x0.to_affine()
-    }*/
+    }
 }
 
 impl<'b> MulAssign<&'b Scalar> for MontgomeryPoint {