Add missing methods as need for integrating the latest version of this crate

Cargo.toml

@@ -6,7 +6,7 @@ authors = [
     "redshiftzero <jen@penumbralabs.xyz>",
 ]
 description = "A prime-order group designed for use in SNARKs over BLS12-377"
-edition = "2018"
+edition = "2021"
 license = "MIT OR Apache-2.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
@@ -16,6 +16,7 @@ license = "MIT OR Apache-2.0"
 cfg-if = "1.0"
 hex = { version = "=0.4.3", default-features = false }
 subtle = { version = "2.5", default-features = false }
+rand_core = { version = "0.6", default-features = false }
 zeroize = { version = "1.7", default-features = false }
 # no-std
 num-bigint = { version = "0.4.4", optional = true, default-features = false }
@@ -38,14 +39,15 @@ once_cell = { version = "1.8", optional = true, default-features = false }
 # compile
 [features]
 default = ["arkworks"]
-alloc = ["once_cell/alloc", "zeroize/alloc"]
+alloc = ["once_cell/alloc", "zeroize/alloc", "rand_core/alloc"]
 std = [
     "alloc",
     "zeroize/std",
     "once_cell/std",
     "num-bigint/std",
     "hex/std",
     "subtle/std",
+    "rand_core/std"
 ]
 parallel = [
     "ark-ff/parallel",

src/ark_curve/constants.rs

@@ -58,22 +58,25 @@ pub static G: Lazy<Fq> = Lazy::new(|| ZETA.pow(*M));
 pub static SQRT_W: u32 = 8;
 
 // Canonical basepoint projective coordinates
-pub static B_X: Lazy<Fq> = Lazy::new(|| {
-    from_ark_fq(ark_ff::MontFp!(
-        "4959445789346820725352484487855828915252512307947624787834978378872129235627"
-    ))
-});
-pub static B_Y: Lazy<Fq> = Lazy::new(|| {
-    from_ark_fq(ark_ff::MontFp!(
-        "6060471950081851567114691557659790004756535011754163002297540472747064943288"
-    ))
-});
-pub static B_T: Lazy<Fq> = Lazy::new(|| {
-    from_ark_fq(ark_ff::MontFp!(
-        "7709528722369014828560854854815397945854484030754980890329689855465844419067"
-    ))
-});
-pub static B_Z: Lazy<Fq> = Lazy::new(|| from_ark_fq(ark_ff::MontFp!("1")));
+pub const B_X: Fq = Fq::from_montgomery_limbs([
+    5825153684096051627,
+    16988948339439369204,
+    186539475124256708,
+    1230075515893193738,
+]);
+pub const B_Y: Fq = Fq::from_montgomery_limbs([
+    9786171649960077610,
+    13527783345193426398,
+    10983305067350511165,
+    1251302644532346138,
+]);
+pub const B_T: Fq = Fq::from_montgomery_limbs([
+    7466800842436274004,
+    14314110021432015475,
+    14108125795146788134,
+    1305086759679105397,
+]);
+pub const B_Z: Fq = Fq::ONE;
 
 // Canonical basepoint affine coordinates
 pub const GENERATOR_X: Fq = Fq::from_montgomery_limbs([

src/ark_curve/element.rs

@@ -46,7 +46,7 @@ impl Group for Element {
     }
 
     fn generator() -> Self {
-        crate::basepoint()
+        Self::GENERATOR
     }
 
     fn mul_bigint(&self, other: impl AsRef<[u64]>) -> Self {
@@ -111,7 +111,7 @@ impl AffineRepr for AffinePoint {
     }
 
     fn generator() -> Self {
-        crate::basepoint().into()
+        Element::GENERATOR.into()
     }
 
     fn from_random_bytes(bytes: &[u8]) -> Option<Self> {

src/ark_curve/element/projective.rs

@@ -8,11 +8,24 @@ use zeroize::Zeroize;
 
 use crate::{ark_curve::EdwardsProjective, Fq, Fr};
 
+use super::super::constants::{B_T, B_X, B_Y, B_Z};
+
 #[derive(Copy, Clone)]
 pub struct Element {
     pub(crate) inner: EdwardsProjective,
 }
 
+impl Element {
+    /// Return the conventional generator for `decaf377`.
+    pub const GENERATOR: Self = Self {
+        inner: EdwardsProjective::new_unchecked(B_X, B_Y, B_T, B_Z),
+    };
+
+    pub const IDENTITY: Self = Self {
+        inner: EdwardsProjective::new_unchecked(Fq::ZERO, Fq::ONE, Fq::ZERO, Fq::ONE),
+    };
+}
+
 impl Hash for Element {
     fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
         self.inner.hash(state);

src/ark_curve/mod.rs

@@ -21,15 +21,3 @@ mod on_curve;
 pub mod r1cs;
 
 pub use bls12_377::Bls12_377;
-
-/// Return the conventional generator for `decaf377`.
-pub fn basepoint() -> Element {
-    Element {
-        inner: EdwardsProjective::new(
-            *constants::B_X,
-            *constants::B_Y,
-            *constants::B_T,
-            *constants::B_Z,
-        ),
-    }
-}

src/fields/fp.rs

@@ -1,7 +1,5 @@
-// Fiat-crypto generates some unused type aliases, but we don't want to edit the generated code at all.
-#![allow(dead_code)]
-
 use cfg_if::cfg_if;
+use rand_core::CryptoRngCore;
 
 use crate::EncodingError;
 
@@ -115,7 +113,6 @@ impl Fp {
             }) // let acc =
     }
 
-    ///
     /// Convert bytes into an Fp element, returning None if these bytes are not already reduced.
     ///
     /// This means that values that cannot be produced by encoding a field element will return
@@ -132,6 +129,17 @@ impl Fp {
     pub fn to_bytes(&self) -> [u8; N_8] {
         self.to_bytes_le()
     }
+
+    /// Sample a random field element uniformly.
+    pub fn rand<R: CryptoRngCore>(rng: &mut R) -> Self {
+        // Sample wide, reduce
+        let bytes = {
+            let mut out = [0u8; N_8 + 16];
+            rng.fill_bytes(&mut out);
+            out
+        };
+        Self::from_le_bytes_mod_order(&bytes)
+    }
 }
 
 #[cfg(test)]

src/fields/fp/u32/wrapper.rs

@@ -6,7 +6,7 @@ use super::{
 const N: usize = N_32;
 
 #[derive(Copy, Clone)]
-pub struct Fp(pub fiat::FpMontgomeryDomainFieldElement);
+pub struct Fp(fiat::FpMontgomeryDomainFieldElement);
 
 impl PartialEq for Fp {
     fn eq(&self, other: &Self) -> bool {

src/fields/fp/u64/wrapper.rs

@@ -6,7 +6,7 @@ use super::{
 const N: usize = N_64;
 
 #[derive(Copy, Clone)]
-pub struct Fp(pub fiat::FpMontgomeryDomainFieldElement);
+pub struct Fp(fiat::FpMontgomeryDomainFieldElement);
 
 impl PartialEq for Fp {
     fn eq(&self, other: &Self) -> bool {

src/fields/fq.rs

@@ -1,7 +1,5 @@
-// Fiat-crypto generates some unused type aliases, but we don't want to edit the generated code at all.
-#![allow(dead_code)]
-
 use cfg_if::cfg_if;
+use rand_core::CryptoRngCore;
 
 use crate::EncodingError;
 
@@ -116,6 +114,17 @@ impl Fq {
     pub fn to_bytes(&self) -> [u8; N_8] {
         self.to_bytes_le()
     }
+
+    /// Sample a random field element uniformly.
+    pub fn rand<R: CryptoRngCore>(rng: &mut R) -> Self {
+        // Sample wide, reduce
+        let bytes = {
+            let mut out = [0u8; N_8 + 16];
+            rng.fill_bytes(&mut out);
+            out
+        };
+        Self::from_le_bytes_mod_order(&bytes)
+    }
 }
 
 #[cfg(test)]

src/fields/fq/u32/wrapper.rs

@@ -8,7 +8,7 @@ use super::{
 const N: usize = N_32;
 
 #[derive(Copy, Clone)]
-pub struct Fq(pub fiat::FqMontgomeryDomainFieldElement);
+pub struct Fq(fiat::FqMontgomeryDomainFieldElement);
 
 impl PartialEq for Fq {
     fn eq(&self, other: &Self) -> bool {

src/fields/fq/u64/wrapper.rs

@@ -8,7 +8,7 @@ use super::{
 const N: usize = N_64;
 
 #[derive(Copy, Clone)]
-pub struct Fq(pub fiat::FqMontgomeryDomainFieldElement);
+pub struct Fq(fiat::FqMontgomeryDomainFieldElement);
 
 impl PartialEq for Fq {
     fn eq(&self, other: &Self) -> bool {

src/fields/fr.rs

@@ -1,7 +1,5 @@
-// Fiat-crypto generates some unused type aliases, but we don't want to edit the generated code at all.
-#![allow(dead_code)]
-
 use cfg_if::cfg_if;
+use rand_core::CryptoRngCore;
 
 use crate::EncodingError;
 
@@ -108,6 +106,17 @@ impl Fr {
     pub fn to_bytes(&self) -> [u8; N_8] {
         self.to_bytes_le()
     }
+
+    /// Sample a random field element uniformly.
+    pub fn rand<R: CryptoRngCore>(rng: &mut R) -> Self {
+        // Sample wide, reduce
+        let bytes = {
+            let mut out = [0u8; N_8 + 16];
+            rng.fill_bytes(&mut out);
+            out
+        };
+        Self::from_le_bytes_mod_order(&bytes)
+    }
 }
 
 #[cfg(test)]

src/fields/fr/u32/wrapper.rs

@@ -6,7 +6,7 @@ use super::{
 const N: usize = N_32;
 
 #[derive(Copy, Clone)]
-pub struct Fr(pub fiat::FrMontgomeryDomainFieldElement);
+pub struct Fr(fiat::FrMontgomeryDomainFieldElement);
 
 impl PartialEq for Fr {
     fn eq(&self, other: &Self) -> bool {

src/fields/fr/u64/wrapper.rs

@@ -6,7 +6,7 @@ use super::{
 const N: usize = N_64;
 
 #[derive(Copy, Clone)]
-pub struct Fr(pub fiat::FrMontgomeryDomainFieldElement);
+pub struct Fr(fiat::FrMontgomeryDomainFieldElement);
 
 impl PartialEq for Fr {
     fn eq(&self, other: &Self) -> bool {

src/lib.rs

@@ -17,8 +17,6 @@ cfg_if! {
 
         pub use ark_curve::{Element, Encoding, ZETA};
 
-        pub use ark_curve::basepoint;
-
         pub use ark_curve::bls12_377::Bls12_377;
 
         #[cfg(feature = "r1cs")]

src/min_curve/element.rs

@@ -108,6 +108,13 @@ impl Element {
             Element { x, y, z, t }
         }
     }
+    ///
+    /// Convenience method to make identity checks more readable.
+    pub fn is_identity(&self) -> bool {
+        // Section 4.5 of Decaf paper states for cofactor 4 curves we can
+        // just check X = 0 to check equality with identity
+        self.x == Fq::ZERO
+    }
 
     pub fn double(self) -> Self {
         // https://eprint.iacr.org/2008/522 Section 3.3
@@ -383,6 +390,85 @@ mod test {
     }
 }
 
+impl From<&Element> for Encoding {
+    fn from(point: &Element) -> Self {
+        point.vartime_compress()
+    }
+}
+
+impl From<Element> for Encoding {
+    fn from(point: Element) -> Self {
+        point.vartime_compress()
+    }
+}
+
+impl TryFrom<&[u8]> for Encoding {
+    type Error = EncodingError;
+
+    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
+        if bytes.len() == 32 {
+            let mut arr = [0u8; 32];
+            arr.copy_from_slice(&bytes[0..32]);
+            Ok(Encoding(arr))
+        } else {
+            Err(EncodingError::InvalidSliceLength)
+        }
+    }
+}
+
+impl From<[u8; 32]> for Encoding {
+    fn from(bytes: [u8; 32]) -> Encoding {
+        Encoding(bytes)
+    }
+}
+
+impl From<Encoding> for [u8; 32] {
+    fn from(enc: Encoding) -> [u8; 32] {
+        enc.0
+    }
+}
+
+impl TryFrom<&Encoding> for Element {
+    type Error = EncodingError;
+    fn try_from(bytes: &Encoding) -> Result<Self, Self::Error> {
+        bytes.vartime_decompress()
+    }
+}
+
+impl TryFrom<Encoding> for Element {
+    type Error = EncodingError;
+    fn try_from(bytes: Encoding) -> Result<Self, Self::Error> {
+        bytes.vartime_decompress()
+    }
+}
+
+impl TryFrom<&[u8]> for Element {
+    type Error = EncodingError;
+
+    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
+        let b: [u8; 32] = bytes
+            .try_into()
+            .map_err(|_| EncodingError::InvalidSliceLength)?;
+
+        Encoding(b).try_into()
+    }
+}
+
+impl TryFrom<[u8; 32]> for Element {
+    type Error = EncodingError;
+
+    fn try_from(bytes: [u8; 32]) -> Result<Self, Self::Error> {
+        let encoding = Encoding(bytes);
+        encoding.try_into()
+    }
+}
+
+impl From<Element> for [u8; 32] {
+    fn from(enc: Element) -> [u8; 32] {
+        enc.vartime_compress().0
+    }
+}
+
 #[cfg(all(test, feature = "arkworks"))]
 mod proptests {
     use super::*;