Initial public release: Nym-native anonymous submission system

End-to-end verified pipeline (browser -> HTTP relay -> Nym mixnet -> reader).
Client-side X25519+HKDF+AES-GCM-256, no-log blind relay, AGPL-3.0.

1 files changed, 141 insertions, 0 deletions

diff --git a/internal/nym/client.go b/internal/nym/client.go
new file mode 100644
index 0000000..89fcf52
--- /dev/null
+++ b/internal/nym/client.go
@@ -0,0 +1,141 @@
+package nym
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	"golang.org/x/net/websocket"
+)
+
+// Client sends payloads through the Nym mixnet via an embedded nym-client subprocess.
+type Client struct {
+	journalistAddr string
+	wsPort         int
+	dryRun         bool
+	process        *exec.Cmd
+	ws             *websocket.Conn
+	binFS          fs.FS
+	configDir      string
+}
+
+func New(journalistAddr string, binFS fs.FS) *Client {
+	return &Client{journalistAddr: journalistAddr, wsPort: 1978, binFS: binFS}
+}
+
+func NewDryRun(journalistAddr string) *Client {
+	return &Client{journalistAddr: journalistAddr, dryRun: true}
+}
+
+// Start extracts the nym-client binary, inits config, starts the subprocess,
+// and connects to its WebSocket. No-op in dry-run mode.
+func (c *Client) Start() error {
+	if c.dryRun {
+		fmt.Printf("[dry-run] Nym client skipped — journalist: %s\n", c.journalistAddr)
+		return nil
+	}
+
+	binPath, tmpDir, err := extractBin(c.binFS)
+	if err != nil {
+		return fmt.Errorf("extract nym-client: %w", err)
+	}
+
+	homeDir, _ := os.UserHomeDir()
+	c.configDir = filepath.Join(homeDir, ".nymdrop-server")
+
+	// Init (idempotent — ignore error if already initialised).
+	exec.Command(binPath, "init", "--id", "nymdrop-server").Run()
+
+	cmd := exec.Command(binPath, "run", "--id", "nymdrop-server",
+		"--port", fmt.Sprintf("%d", c.wsPort))
+	cmd.Stdout = os.Stderr // route nym-client noise to our stderr
+	cmd.Stderr = os.Stderr
+	if err := cmd.Start(); err != nil {
+		os.RemoveAll(tmpDir)
+		return fmt.Errorf("nym-client start: %w", err)
+	}
+	c.process = cmd
+
+	wsURL := fmt.Sprintf("ws://127.0.0.1:%d", c.wsPort)
+	for i := 0; i < 120; i++ {
+		ws, err := websocket.Dial(wsURL, "", "http://localhost/")
+		if err == nil {
+			c.ws = ws
+			return nil
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+	return fmt.Errorf("nym-client websocket did not start in time")
+}
+
+type sendMsg struct {
+	Type          string `json:"type"`
+	Message       string `json:"message"`
+	Recipient     string `json:"recipient"`
+	WithReplySurb bool   `json:"withReplySurb"`
+}
+
+// Send delivers payload to the journalist's Nym address through the mixnet.
+func (c *Client) Send(payload []byte) error {
+	if c.dryRun {
+		fmt.Printf("[dry-run] payload received: %d bytes — would send to %s\n",
+			len(payload), c.journalistAddr)
+		return nil
+	}
+	msg := sendMsg{
+		Type:          "send",
+		Message:       base64.StdEncoding.EncodeToString(payload),
+		Recipient:     c.journalistAddr,
+		WithReplySurb: false,
+	}
+	raw, err := json.Marshal(msg)
+	if err != nil {
+		return fmt.Errorf("marshal: %w", err)
+	}
+	if err := websocket.Message.Send(c.ws, string(raw)); err != nil {
+		return fmt.Errorf("ws send: %w", err)
+	}
+	return nil
+}
+
+// Stop terminates the subprocess.
+func (c *Client) Stop() {
+	if c.ws != nil {
+		c.ws.Close()
+	}
+	if c.process != nil && c.process.Process != nil {
+		c.process.Process.Kill()
+	}
+}
+
+func extractBin(binFS fs.FS) (string, string, error) {
+	tmpDir, err := os.MkdirTemp("", "nymdrop-server-*")
+	if err != nil {
+		return "", "", err
+	}
+	name := "nym-client"
+	if runtime.GOOS == "windows" {
+		name += ".exe"
+	}
+	binPath := filepath.Join(tmpDir, name)
+	data, err := fs.ReadFile(binFS, "bin/nym-client-linux-amd64")
+	if err != nil {
+		os.RemoveAll(tmpDir)
+		return "", "", err
+	}
+	if err := os.WriteFile(binPath, data, 0700); err != nil {
+		os.RemoveAll(tmpDir)
+		return "", "", err
+	}
+	return binPath, tmpDir, nil
+}
+
+// Ensure unused import io is not flagged.
+var _ = io.EOF