initial commit

.github/workflows/ci.yml

@@ -0,0 +1,64 @@
+name: CI
+on:
+  push:
+    tags:
+      - v*
+  pull_request:
+jobs:
+  linux:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/setup-go@v2
+        with:
+          go-version: 1.16.5
+      - uses: actions/checkout@v2
+      - name: go build
+        run: go build -v -ldflags '-w -s -extldflags -static' -o redpwnpow-linux-amd64 ./cmd/redpwnpow
+      - uses: actions/upload-artifact@v2
+        with:
+          name: linux
+          path: redpwnpow-linux-*
+  darwin:
+    runs-on: macos-10.15
+    steps:
+      - uses: actions/setup-go@v2
+        with:
+          go-version: 1.16.5
+      - uses: actions/checkout@v2
+      - name: go build
+        run: |
+          lib_tmp=$(mktemp -d)
+          cp /usr/local/opt/gmp/lib/libgmp.a "$lib_tmp"
+          go build -v -ldflags "-w -s -extldflags -L$lib_tmp" -o redpwnpow-darwin-amd64 ./cmd/redpwnpow
+      - uses: actions/upload-artifact@v2
+        with:
+          name: darwin
+          path: redpwnpow-darwin-*
+  windows:
+    runs-on: windows-2019
+    steps:
+      - uses: msys2/setup-msys2@v2
+        with:
+          install: mingw-w64-x86_64-go mingw-w64-x86_64-gcc mingw-w64-x86_64-gmp
+      - uses: actions/checkout@v2
+      - name: go build
+        shell: msys2 {0}
+        run: go build -v -ldflags '-w -s -extldflags -static' -o redpwnpow-windows-amd64.exe ./cmd/redpwnpow
+      - uses: actions/upload-artifact@v2
+        with:
+          name: windows
+          path: redpwnpow-windows-*
+  release:
+    runs-on: ubuntu-20.04
+    if: startsWith(github.ref, 'refs/tags/v')
+    needs:
+      - linux
+      - darwin
+      - windows
+    steps:
+      - uses: actions/download-artifact@v2
+      - uses: softprops/action-gh-release@v1
+        with:
+          files: */redpwnpow-*
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

LICENSE

@@ -0,0 +1,29 @@
+BSD 3-Clause License
+
+Copyright (c) 2021, redpwn
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

@@ -0,0 +1,3 @@
+# redpwn/pow
+
+redpwn/pow is used by [redpwn/jail](https://github.com/redpwn/jail).

cmd/redpwnpow/redpwnpow.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/redpwn/pow"
+)
+
+func run() error {
+	if len(os.Args) < 2 {
+		return errors.New("usage: redpwnpow challenge")
+	}
+	c, err := pow.DecodeChallenge(os.Args[1])
+	if err != nil {
+		return fmt.Errorf("decode challenge: %w", err)
+	}
+	fmt.Println(c.Solve())
+	return nil
+}
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

cmd/redpwnpow/run.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# redpwnpow proof of work runner
+# https://github.com/redpwn/pow/blob/master/cmd/redpwnpow/run.sh
+
+set -e
+version=v0.0.1
+challenge=$1
+run() {
+  cache_root=$HOME/.cache/redpwnpow
+  mkdir -p "$cache_root"
+  cache_path="$cache_root/redpwnpow-$version"
+  case $(uname | tr '[:upper:]' '[:lower:]') in
+    linux*) release=linux-amd64;;
+    darwin*) release=darwin-amd64;;
+    msys*|mingw*|cygwin*) release=windows-amd64.exe;;
+    *) echo unknown operating system >&2; exit 1
+  esac
+  [ -e "$cache_path" ] || curl -sSfLo "$cache_path" "https://github.com/redpwn/pow/releases/download/$version/redpwnpow-$release" && chmod u+x "$cache_path"
+  "$cache_path" "$challenge"
+}
+run

go.mod

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+module github.com/redpwn/pow
+
+go 1.16
+
+require github.com/ncw/gmp v1.0.4

go.sum

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+github.com/ncw/gmp v1.0.4 h1:/f+vRpbpMIqDWfTGqYgCIuhoVfiyVf0ygsnwayqjGwU=
+github.com/ncw/gmp v1.0.4/go.mod h1:cDbCx93DFhzP32H3rnwwt6QnIXNL5wu4jLPCNaExheI=

pow.go

@@ -0,0 +1,108 @@
+package pow
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/ncw/gmp"
+)
+
+const version = "s"
+
+var (
+	mod = gmp.NewInt(0)
+	exp = gmp.NewInt(0)
+	one = gmp.NewInt(1)
+	two = gmp.NewInt(2)
+)
+
+func init() {
+	mod.Lsh(two, 1278)
+	exp.Div(mod, gmp.NewInt(4))
+	mod.Sub(mod, one)
+}
+
+type challenge struct {
+	d uint32
+	x *gmp.Int
+}
+
+func DecodeChallenge(v string) (*challenge, error) {
+	parts := strings.SplitN(v, ".", 3)
+	if len(parts) != 3 || parts[0] != version {
+		return nil, errors.New("incorrect version")
+	}
+	dBytes, err := base64.StdEncoding.DecodeString(parts[1])
+	if err != nil {
+		return nil, err
+	}
+	if len(dBytes) > 4 {
+		return nil, errors.New("difficulty too long")
+	}
+	// pad start with 0s to 4 bytes
+	dBytes = append(make([]byte, 4-len(dBytes)), dBytes...)
+	xBytes, err := base64.StdEncoding.DecodeString(parts[2])
+	if err != nil {
+		return nil, err
+	}
+	d := binary.BigEndian.Uint32(dBytes)
+	x := gmp.NewInt(0).SetBytes(xBytes)
+	return &challenge{d: d, x: x}, nil
+}
+
+func GenerateChallenge(d uint32) *challenge {
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		panic(err)
+	}
+	return &challenge{
+		x: gmp.NewInt(0).SetBytes(b),
+		d: d,
+	}
+}
+
+func (c *challenge) String() string {
+	b := make([]byte, 4)
+	binary.BigEndian.PutUint32(b, c.d)
+	return fmt.Sprintf("%s.%s.%s", version, base64.StdEncoding.EncodeToString(b), base64.StdEncoding.EncodeToString(c.x.Bytes()))
+}
+
+func (c challenge) Solve() string {
+	for i := uint32(0); i < c.d; i += 1 {
+		c.x.Exp(c.x, exp, mod)
+		c.x.Xor(c.x, one)
+	}
+	return fmt.Sprintf("%s.%s", version, base64.StdEncoding.EncodeToString(c.x.Bytes()))
+}
+
+func decodeSolution(s string) (*gmp.Int, error) {
+	parts := strings.SplitN(s, ".", 2)
+	if len(parts) != 2 || parts[0] != version {
+		return nil, errors.New("incorrect version")
+	}
+	yBytes, err := base64.StdEncoding.DecodeString(parts[1])
+	if err != nil {
+		return nil, err
+	}
+	return gmp.NewInt(0).SetBytes(yBytes), nil
+}
+
+func (c challenge) Check(s string) (bool, error) {
+	y, err := decodeSolution(s)
+	if err != nil {
+		return false, fmt.Errorf("decode solution: %w", err)
+	}
+	for i := uint32(0); i < c.d; i += 1 {
+		y.Xor(y, one)
+		y.Exp(y, two, mod)
+	}
+	if c.x.Cmp(y) == 0 {
+		return true, nil
+	}
+	c.x.Sub(mod, c.x)
+	return c.x.Cmp(y) == 0, nil
+}