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core/vm: use optimized bigint #26021

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Oct 27, 2022
Merged

core/vm: use optimized bigint #26021

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13 changes: 5 additions & 8 deletions core/vm/contracts.go
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ import (
"github.com/ethereum/go-ethereum/crypto/bls12381"
"github.com/ethereum/go-ethereum/crypto/bn256"
"github.com/ethereum/go-ethereum/params"
big2 "github.com/holiman/big"
"golang.org/x/crypto/ripemd160"
)

Expand Down Expand Up @@ -377,23 +378,19 @@ func (c *bigModExp) Run(input []byte) ([]byte, error) {
}
// Retrieve the operands and execute the exponentiation
var (
base = new(big.Int).SetBytes(getData(input, 0, baseLen))
exp = new(big.Int).SetBytes(getData(input, baseLen, expLen))
mod = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen))
base = new(big2.Int).SetBytes(getData(input, 0, baseLen))
exp = new(big2.Int).SetBytes(getData(input, baseLen, expLen))
mod = new(big2.Int).SetBytes(getData(input, baseLen+expLen, modLen))
v []byte
)
switch {
case mod.BitLen() == 0:
// Modulo 0 is undefined, return zero
return common.LeftPadBytes([]byte{}, int(modLen)), nil
case base.Cmp(common.Big1) == 0:
case base.BitLen() == 1: // a bit length of 1 means it's 1 (or -1).
//If base == 1, then we can just return base % mod (if mod >= 1, which it is)
v = base.Mod(base, mod).Bytes()
//case mod.Bit(0) == 0:
// // Modulo is even
// v = math.FastExp(base, exp, mod).Bytes()
default:
// Modulo is odd
v = base.Exp(base, exp, mod).Bytes()
}
return common.LeftPadBytes(v, int(modLen)), nil
Expand Down