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core/vm: use optimized bigint (#26021)

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This commit is contained in:
Martin Holst Swende 2022-10-27 10:39:01 +02:00 committed by Jerry
parent a7bf4ba6bd
commit 7303e59f52
1 changed files with 17 additions and 10 deletions
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27
core/vm/contracts.go
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@ -29,8 +29,7 @@ import (
"github.com/ethereum/go-ethereum/crypto/bls12381" "github.com/ethereum/go-ethereum/crypto/bls12381"
"github.com/ethereum/go-ethereum/crypto/bn256" "github.com/ethereum/go-ethereum/crypto/bn256"
"github.com/ethereum/go-ethereum/params" "github.com/ethereum/go-ethereum/params"
big2 "github.com/holiman/big"
//lint:ignore SA1019 Needed for precompile
"golang.org/x/crypto/ripemd160" "golang.org/x/crypto/ripemd160"
) )
@ -266,9 +265,10 @@ var (
// modexpMultComplexity implements bigModexp multComplexity formula, as defined in EIP-198 // modexpMultComplexity implements bigModexp multComplexity formula, as defined in EIP-198
// //
// def mult_complexity(x): // def mult_complexity(x):
// if x <= 64: return x ** 2 //
// elif x <= 1024: return x ** 2 // 4 + 96 * x - 3072 // if x <= 64: return x ** 2
// else: return x ** 2 // 16 + 480 * x - 199680 // elif x <= 1024: return x ** 2 // 4 + 96 * x - 3072
// else: return x ** 2 // 16 + 480 * x - 199680
// //
// where is x is max(length_of_MODULUS, length_of_BASE) // where is x is max(length_of_MODULUS, length_of_BASE)
func modexpMultComplexity(x *big.Int) *big.Int { func modexpMultComplexity(x *big.Int) *big.Int {
@ -379,15 +379,22 @@ func (c *bigModExp) Run(input []byte) ([]byte, error) {
} }
// Retrieve the operands and execute the exponentiation // Retrieve the operands and execute the exponentiation
var ( var (
base = new(big.Int).SetBytes(getData(input, 0, baseLen)) base = new(big2.Int).SetBytes(getData(input, 0, baseLen))
exp = new(big.Int).SetBytes(getData(input, baseLen, expLen)) exp = new(big2.Int).SetBytes(getData(input, baseLen, expLen))
mod = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen)) mod = new(big2.Int).SetBytes(getData(input, baseLen+expLen, modLen))
v []byte
) )
if mod.BitLen() == 0 { switch {
case mod.BitLen() == 0:
// Modulo 0 is undefined, return zero // Modulo 0 is undefined, return zero
return common.LeftPadBytes([]byte{}, int(modLen)), nil return common.LeftPadBytes([]byte{}, int(modLen)), nil
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()
default:
v = base.Exp(base, exp, mod).Bytes()
} }
return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil return common.LeftPadBytes(v, int(modLen)), nil
} }
// newCurvePoint unmarshals a binary blob into a bn256 elliptic curve point, // newCurvePoint unmarshals a binary blob into a bn256 elliptic curve point,