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fold multiplication

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This commit is contained in:
NikVolf 2017-04-03 12:57:18 +03:00
parent d6baadbaf2
commit df72c9c6cc
1 changed files with 4 additions and 19 deletions
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23
ethcore/src/builtin.rs
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@ -435,9 +435,9 @@ impl Impl for Bn128ParingImpl {
/// - any of odd points does not belong to bn128 curve /// - any of odd points does not belong to bn128 curve
/// - any of even points does not belong to the twisted bn128 curve over the field F_p^2 = F_p[i] / (i^2 + 1) /// - any of even points does not belong to the twisted bn128 curve over the field F_p^2 = F_p[i] / (i^2 + 1)
fn execute(&self, input: &[u8], output: &mut BytesRef) -> Result<(), Error> { fn execute(&self, input: &[u8], output: &mut BytesRef) -> Result<(), Error> {
use bn::{AffineG1, AffineG2, Fq, Fq2, pairing, G1, G2}; use bn::{AffineG1, AffineG2, Fq, Fq2, pairing, G1, G2, Gt};
let elements = input.len() / 192; // (a, b_a, b_b - each 64-byte affine coordinate) let elements = input.len() / 192; // (a, b_a, b_b - each 64-byte affine coordinates)
if input.len() % 192 != 0 { if input.len() % 192 != 0 {
return Err("Invalid input length, must be multiple of 192 (3 * (32*2))".into()) return Err("Invalid input length, must be multiple of 192 (3 * (32*2))".into())
} }
@ -476,23 +476,8 @@ impl Impl for Bn128ParingImpl {
), ),
)); ));
}; };
let mul = if elements == 1 {
let (a, b) = vals[0]; let mul = vals.into_iter().fold(Gt::one(), |s, (a, b)| s * pairing(a, b));
pairing(a, b)
} else {
let mut drain = vals.drain(..);
let mut mul = {
let (a, b) = drain.next()
.expect("Checked above that elements > 1, so 0th element should exist; qed");
pairing(a, b)
};
for _ in 1..elements {
let (a, b) = drain.next()
.expect("this element should exist, because we do next() no more than elements-1 times; qed");
mul = mul * pairing(a, b);
}
mul
};
if mul == *bn128_gen::P1_P2_PAIRING { if mul == *bn128_gen::P1_P2_PAIRING {
U256::one() U256::one()