gaspersic/go-ethereum
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

crypto/secp256k1: remove external LGPL dependencies (#17239)

Browse Source
This commit is contained in:
Péter Szilágyi
2018-07-26 14:33:13 +03:00
committed by Felix Lange
parent 11a402f747
commit d9575e92fc
4 changed files with 69 additions and 72 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
crypto/secp256k1/curve.go
View File

@ -1,5 +1,6 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Copyright 2011 ThePiachu. All rights reserved.
// Copyright 2015 Jeffrey Wilcke, Felix Lange, Gustav Simonsson. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
@ -35,8 +36,6 @@ import (
"crypto/elliptic"
"math/big"
"unsafe"
"github.com/ethereum/go-ethereum/common/math"
)
/*
@ -45,6 +44,27 @@ extern int secp256k1_ext_scalar_mul(const secp256k1_context* ctx, const unsigned
*/
import "C"
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
)
// 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.
//
@ -231,8 +251,9 @@ func (BitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int,
// Do the multiplication in C, updating point.
point := make([]byte, 64)
math.ReadBits(Bx, point[:32])
math.ReadBits(By, point[32:])
readBits(Bx, point[:32])
readBits(By, point[32:])
pointPtr := (*C.uchar)(unsafe.Pointer(&point[0]))
scalarPtr := (*C.uchar)(unsafe.Pointer(&scalar[0]))
res := C.secp256k1_ext_scalar_mul(context, pointPtr, scalarPtr)
@ -264,8 +285,8 @@ 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
math.ReadBits(x, ret[1:1+byteLen])
math.ReadBits(y, ret[1+byteLen:])
readBits(x, ret[1:1+byteLen])
readBits(y, ret[1+byteLen:])
return ret
}
@ -290,11 +311,11 @@ func init() {
// See SEC 2 section 2.7.1
// curve parameters taken from:
// http://www.secg.org/collateral/sec2_final.pdf
theCurve.P = math.MustParseBig256("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F")
theCurve.N = math.MustParseBig256("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141")
theCurve.B = math.MustParseBig256("0x0000000000000000000000000000000000000000000000000000000000000007")
theCurve.Gx = math.MustParseBig256("0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798")
theCurve.Gy = math.MustParseBig256("0x483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8")
theCurve.P, _ = new(big.Int).SetString("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F", 0)
theCurve.N, _ = new(big.Int).SetString("0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 0)
theCurve.B, _ = new(big.Int).SetString("0x0000000000000000000000000000000000000000000000000000000000000007", 0)
theCurve.Gx, _ = new(big.Int).SetString("0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798", 0)
theCurve.Gy, _ = new(big.Int).SetString("0x483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8", 0)
theCurve.BitSize = 256
}