arithmetic skeleton

evm/src/bls381_arithmetic.rs

@@ -0,0 +1,110 @@
+use std::ops::{Add, Div, Mul, Neg, Sub};
+
+use ethereum_types::U512;
+use rand::distributions::{Distribution, Standard};
+use rand::Rng;
+
+pub const BLS_BASE: U512 = U512([
+    0xb9feffffffffaaab,
+    0x1eabfffeb153ffff,
+    0x6730d2a0f6b0f624,
+    0x64774b84f38512bf,
+    0x4b1ba7b6434bacd7,
+    0x1a0111ea397fe69a,
+    0x0,
+    0x0,
+]);
+
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub struct Fp {
+    pub val: U512,
+}
+
+impl Fp {
+    pub fn new(val: usize) -> Fp {
+        Fp {
+            val: U512::from(val),
+        }
+    }
+}
+
+impl Distribution<Fp> for Standard {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Fp {
+        let xs = rng.gen::<[u64;8]>();
+        Fp {
+            val: U512(xs) % BLS_BASE,
+        }
+    }
+}
+
+impl Add for Fp {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Fp {
+            val: (self.val + other.val) % BLS_BASE,
+        }
+    }
+}
+
+impl Neg for Fp {
+    type Output = Self;
+
+    fn neg(self) -> Self::Output {
+        Fp {
+            val: (BLS_BASE - self.val) % BLS_BASE,
+        }
+    }
+}
+
+impl Sub for Fp {
+    type Output = Self;
+
+    fn sub(self, other: Self) -> Self {
+        Fp {
+            val: (BLS_BASE + self.val - other.val) % BLS_BASE,
+        }
+    }
+}
+
+#[allow(clippy::suspicious_arithmetic_impl)]
+impl Mul for Fp {
+    type Output = Self;
+
+    fn mul(self, other: Self) -> Self {
+        Fp {
+            val: (self.val).overflowing_mul(other.val).0 % BLS_BASE,
+        }
+    }
+}
+
+impl Fp {
+    pub fn inv(self) -> Fp {
+        exp_fp(self, BLS_BASE - 2)
+    }
+}
+
+#[allow(clippy::suspicious_arithmetic_impl)]
+impl Div for Fp {
+    type Output = Self;
+
+    fn div(self, rhs: Self) -> Self::Output {
+        self * rhs.inv()
+    }
+}
+
+pub const ZERO_FP: Fp = Fp { val: U512::zero() };
+pub const UNIT_FP: Fp = Fp { val: U512::one() };
+
+fn exp_fp(x: Fp, e: U512) -> Fp {
+    let mut current = x;
+    let mut product = Fp { val: U512::one() };
+
+    for j in 0..512 {
+        if e.bit(j) {
+            product = product * current;
+        }
+        current = current * current;
+    }
+    product
+}

evm/src/lib.rs

@@ -8,6 +8,7 @@
 
 pub mod all_stark;
 pub mod arithmetic;
+pub mod bls381_arithmetic;
 pub mod bn254_arithmetic;
 pub mod bn254_pairing;
 pub mod config;