From 26cf656bde25e3d2e08601a9d9d1616d58b785f0 Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Mon, 27 Feb 2017 12:13:05 +0100 Subject: [PATCH] common/math, crypto/secp256k1: make ReadBits public in package math --- common/math/big.go | 9 ++++---- common/math/big_test.go | 16 +++++++++++++ crypto/secp256k1/curve.go | 6 +++-- crypto/secp256k1/curve_test.go | 39 -------------------------------- crypto/secp256k1/secp256.go | 14 ------------ crypto/secp256k1/secp256_test.go | 5 ++-- 6 files changed, 27 insertions(+), 62 deletions(-) delete mode 100644 crypto/secp256k1/curve_test.go diff --git a/common/math/big.go b/common/math/big.go index 072ee09938..704ca40a93 100644 --- a/common/math/big.go +++ b/common/math/big.go @@ -102,14 +102,15 @@ func PaddedBigBytes(bigint *big.Int, n int) []byte { return bigint.Bytes() } ret := make([]byte, n) - readBits(ret, bigint.Bits()) + ReadBits(bigint, ret) return ret } -// reads little-endian words as big-endian bytes into buf. -func readBits(buf []byte, words []big.Word) { +// 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 words { + for _, d := range bigint.Bits() { for j := 0; j < wordBytes && i > 0; j++ { i-- buf[i] = byte(d) diff --git a/common/math/big_test.go b/common/math/big_test.go index bf3ba58e0a..6eb13f4f12 100644 --- a/common/math/big_test.go +++ b/common/math/big_test.go @@ -18,6 +18,7 @@ package math import ( "bytes" + "encoding/hex" "math/big" "testing" ) @@ -138,6 +139,21 @@ func BenchmarkPaddedBigBytes(b *testing.B) { } } +func TestReadBits(t *testing.T) { + check := func(input string) { + want, _ := hex.DecodeString(input) + int, _ := new(big.Int).SetString(input, 16) + buf := make([]byte, len(want)) + ReadBits(int, buf) + if !bytes.Equal(buf, want) { + t.Errorf("have: %x\nwant: %x", buf, want) + } + } + check("000000000000000000000000000000000000000000000000000000FEFCF3F8F0") + check("0000000000012345000000000000000000000000000000000000FEFCF3F8F0") + check("18F8F8F1000111000110011100222004330052300000000000000000FEFCF3F8F0") +} + func TestU256(t *testing.T) { tests := []struct{ x, y *big.Int }{ {x: big.NewInt(0), y: big.NewInt(0)}, diff --git a/crypto/secp256k1/curve.go b/crypto/secp256k1/curve.go index 61cad54636..ec6d266cec 100644 --- a/crypto/secp256k1/curve.go +++ b/crypto/secp256k1/curve.go @@ -36,6 +36,8 @@ import ( "math/big" "sync" "unsafe" + + "github.com/ethereum/go-ethereum/common/math" ) /* @@ -230,8 +232,8 @@ func (BitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int, // Do the multiplication in C, updating point. point := make([]byte, 64) - readBits(point[:32], Bx) - readBits(point[32:], By) + math.ReadBits(Bx, point[:32]) + math.ReadBits(By, point[32:]) pointPtr := (*C.uchar)(unsafe.Pointer(&point[0])) scalarPtr := (*C.uchar)(unsafe.Pointer(&scalar[0])) res := C.secp256k1_pubkey_scalar_mul(context, pointPtr, scalarPtr) diff --git a/crypto/secp256k1/curve_test.go b/crypto/secp256k1/curve_test.go deleted file mode 100644 index d915ee8525..0000000000 --- a/crypto/secp256k1/curve_test.go +++ /dev/null @@ -1,39 +0,0 @@ -// Copyright 2015 The go-ethereum Authors -// This file is part of the go-ethereum library. -// -// The go-ethereum library is free software: you can redistribute it and/or modify -// it under the terms of the GNU Lesser General Public License as published by -// the Free Software Foundation, either version 3 of the License, or -// (at your option) any later version. -// -// The go-ethereum library is distributed in the hope that it will be useful, -// but WITHOUT ANY WARRANTY; without even the implied warranty of -// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -// GNU Lesser General Public License for more details. -// -// You should have received a copy of the GNU Lesser General Public License -// along with the go-ethereum library. If not, see . - -package secp256k1 - -import ( - "bytes" - "encoding/hex" - "math/big" - "testing" -) - -func TestReadBits(t *testing.T) { - check := func(input string) { - want, _ := hex.DecodeString(input) - int, _ := new(big.Int).SetString(input, 16) - buf := make([]byte, len(want)) - readBits(buf, int) - if !bytes.Equal(buf, want) { - t.Errorf("have: %x\nwant: %x", buf, want) - } - } - check("000000000000000000000000000000000000000000000000000000FEFCF3F8F0") - check("0000000000012345000000000000000000000000000000000000FEFCF3F8F0") - check("18F8F8F1000111000110011100222004330052300000000000000000FEFCF3F8F0") -} diff --git a/crypto/secp256k1/secp256.go b/crypto/secp256k1/secp256.go index 1a152a6706..0ffa04fe09 100644 --- a/crypto/secp256k1/secp256.go +++ b/crypto/secp256k1/secp256.go @@ -38,7 +38,6 @@ import "C" import ( "errors" - "math/big" "unsafe" ) @@ -129,16 +128,3 @@ func checkSignature(sig []byte) error { } return nil } - -// reads num into buf as big-endian bytes. -func readBits(buf []byte, num *big.Int) { - const wordLen = int(unsafe.Sizeof(big.Word(0))) - i := len(buf) - for _, d := range num.Bits() { - for j := 0; j < wordLen && i > 0; j++ { - i-- - buf[i] = byte(d) - d >>= 8 - } - } -} diff --git a/crypto/secp256k1/secp256_test.go b/crypto/secp256k1/secp256_test.go index 287ab512ec..f6582ecd54 100644 --- a/crypto/secp256k1/secp256_test.go +++ b/crypto/secp256k1/secp256_test.go @@ -24,6 +24,7 @@ import ( "encoding/hex" "testing" + "github.com/ethereum/go-ethereum/common/math" "github.com/ethereum/go-ethereum/crypto/randentropy" ) @@ -35,9 +36,7 @@ func generateKeyPair() (pubkey, privkey []byte) { panic(err) } pubkey = elliptic.Marshal(S256(), key.X, key.Y) - privkey = make([]byte, 32) - readBits(privkey, key.D) - return pubkey, privkey + return pubkey, math.PaddedBigBytes(key.D, 32) } func randSig() []byte {