f6a437d4c9
This commit modifies the pre-computed table used to optimize the secp256k1 scalar multiplication to a string instead of a byte slice. This change makes the compile more efficient since the Go compiler internally represents bytes slices inefficiently. This reduces the memory needed to compile btcec to 3MB versus the previous 40MB before this change. In addition, it modifies the code which loads the pre-computed table to deserialize directly into the table instead of into locals that are then copied. Fixes #297.
64 lines
1.8 KiB
Go
64 lines
1.8 KiB
Go
// Copyright 2015 Conformal Systems LLC. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file is ignored during the regular build due to the following build tag.
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// It is called by go generate and used to automatically generate pre-computed
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// tables used to accelerate operations.
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// +build ignore
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package main
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import (
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"bytes"
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"compress/zlib"
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"encoding/base64"
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"fmt"
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"log"
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"os"
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"github.com/btcsuite/btcd/btcec"
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)
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func main() {
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fi, err := os.Create("secp256k1.go")
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if err != nil {
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log.Fatal(err)
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}
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defer fi.Close()
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// Compress the serialized byte points.
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serialized := btcec.S256().SerializedBytePoints()
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var compressed bytes.Buffer
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w := zlib.NewWriter(&compressed)
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if _, err := w.Write(serialized); err != nil {
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fmt.Println(err)
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os.Exit(1)
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}
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w.Close()
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// Encode the compressed byte points with base64.
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encoded := make([]byte, base64.StdEncoding.EncodedLen(compressed.Len()))
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base64.StdEncoding.Encode(encoded, compressed.Bytes())
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fmt.Fprintln(fi, "// Copyright (c) 2015 Conformal Systems LLC.")
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fmt.Fprintln(fi, "// Use of this source code is governed by an ISC")
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fmt.Fprintln(fi, "// license that can be found in the LICENSE file.")
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fmt.Fprintln(fi)
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fmt.Fprintln(fi, "package btcec")
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fmt.Fprintln(fi)
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fmt.Fprintln(fi, "// Auto-generated file (see genprecomps.go)")
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fmt.Fprintln(fi, "// DO NOT EDIT")
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fmt.Fprintln(fi)
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fmt.Fprintf(fi, "var secp256k1BytePoints = %q\n", string(encoded))
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a1, b1, a2, b2 := btcec.S256().EndomorphismVectors()
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fmt.Println("The following values are the computed linearly " +
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"independent vectors needed to make use of the secp256k1 " +
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"endomorphism:")
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fmt.Printf("a1: %x\n", a1)
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fmt.Printf("b1: %x\n", b1)
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fmt.Printf("a2: %x\n", a2)
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fmt.Printf("b2: %x\n", b2)
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}
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