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crypto/secp256k1: use ReadBits from common/math (#32430)

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cui 2025-08-14 20:32:45 +08:00 committed by GitHub
parent 25cce4dfe4
commit e798e26c69
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GPG key ID: B5690EEEBB952194
2 changed files with 7 additions and 24 deletions
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25
crypto/secp256k1/curve.go
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@ -35,29 +35,10 @@ package secp256k1
import (
"crypto/elliptic"
"math/big"
)
const (
// number of bits in a big.Word
wordBits = 32 << (uint64(^big.Word(0)) >> 63)
// number of bytes in a big.Word
wordBytes = wordBits / 8
"github.com/ethereum/go-ethereum/common/math"
)
// readBits encodes the absolute value of bigint as big-endian bytes. Callers
// must ensure that buf has enough space. If buf is too short the result will
// be incomplete.
func readBits(bigint *big.Int, buf []byte) {
i := len(buf)
for _, d := range bigint.Bits() {
for j := 0; j < wordBytes && i > 0; j++ {
i--
buf[i] = byte(d)
d >>= 8
}
}
}
// This code is from https://github.com/ThePiachu/GoBit and implements
// several Koblitz elliptic curves over prime fields.
//
@ -257,8 +238,8 @@ func (bitCurve *BitCurve) Marshal(x, y *big.Int) []byte {
byteLen := (bitCurve.BitSize + 7) >> 3
ret := make([]byte, 1+2*byteLen)
ret[0] = 4 // uncompressed point flag
readBits(x, ret[1:1+byteLen])
readBits(y, ret[1+byteLen:])
math.ReadBits(x, ret[1:1+byteLen])
math.ReadBits(y, ret[1+byteLen:])
return ret
}

6
crypto/secp256k1/scalar_mult_cgo.go
View file

@ -10,6 +10,8 @@ package secp256k1
import (
"math/big"
"unsafe"
"github.com/ethereum/go-ethereum/common/math"
)
/*
@ -34,8 +36,8 @@ func (bitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int,
// Do the multiplication in C, updating point.
point := make([]byte, 64)
readBits(Bx, point[:32])
readBits(By, point[32:])
math.ReadBits(Bx, point[:32])
math.ReadBits(By, point[32:])
pointPtr := (*C.uchar)(unsafe.Pointer(&point[0]))
scalarPtr := (*C.uchar)(unsafe.Pointer(&scalar[0]))