Add evote netdemo: run the multi-party ceremony from the CLI

New subcommand runs the entire election as separate parties over the
Rust-signed transport, printing per-phase progress and the verified message
count. --verbose logs every signed envelope (from -> to : type, signature OK).
--voters/--options are validated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

cmd/evote/netdemo.go

@@ -0,0 +1,114 @@
+package main
+
+import (
+	"crypto/rand"
+	"fmt"
+	"math/big"
+	"sort"
+
+	"github.com/spf13/cobra"
+	"github.com/user/evote/pkg/party"
+	"github.com/user/evote/pkg/protocol"
+)
+
+var (
+	netVoters  int
+	netOptions int
+	netVerbose bool
+)
+
+var netdemoCmd = &cobra.Command{
+	Use:   "netdemo",
+	Short: "Run the full election as separate parties over Rust-signed transport",
+	Long: "Runs setup, voting, tally, and verification as distinct endpoints " +
+		"(setup component, 4 control components, electoral board, voting server, " +
+		"voters, verifier) communicating only through Ed25519-signed, X25519-" +
+		"encrypted messages — all transport cryptography performed in Rust.",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if netVoters < 1 || netVoters > 1000 {
+			return fmt.Errorf("--voters must be in [1, 1000], got %d", netVoters)
+		}
+		if netOptions < 1 || netOptions > 1000 {
+			return fmt.Errorf("--options must be in [1, 1000], got %d", netOptions)
+		}
+		return runNetDemo(netVoters, netOptions, netVerbose)
+	},
+}
+
+func init() {
+	netdemoCmd.Flags().IntVar(&netVoters, "voters", 5, "Number of voters")
+	netdemoCmd.Flags().IntVar(&netOptions, "options", 3, "Number of voting options")
+	netdemoCmd.Flags().BoolVar(&netVerbose, "verbose", false, "Log every transport message")
+	rootCmd.AddCommand(netdemoCmd)
+}
+
+func runNetDemo(voters, options int, verbose bool) error {
+	cfg := protocol.DefaultConfig(voters, options)
+
+	logf := func(format string, a ...any) { fmt.Printf(format+"\n", a...) }
+	if !verbose {
+		// Non-verbose: suppress the per-message transport lines but keep phase
+		// summaries. The bus log lines start with "  [transport]".
+		logf = func(format string, a ...any) {
+			if len(format) >= 14 && format[:14] == "  [transport] " {
+				return
+			}
+			fmt.Printf(format+"\n", a...)
+		}
+	}
+
+	fmt.Println("========================================")
+	fmt.Println(" Swiss Post E-Voting — Multi-Party PoC")
+	fmt.Println("========================================")
+	fmt.Printf(" Voters: %d, Options: %d, Parties: %d\n",
+		voters, options, 4+cfg.NumCCs+voters)
+
+	c, err := party.NewCeremony(cfg, logf)
+	if err != nil {
+		return err
+	}
+	if err := c.Handshake(); err != nil {
+		return err
+	}
+	if err := c.RunSetup(); err != nil {
+		return err
+	}
+	if err := c.RunCards(); err != nil {
+		return err
+	}
+
+	// Random selections (one option per voter) via CSPRNG.
+	selections := make([][]int, voters)
+	for v := 0; v < voters; v++ {
+		n, err := rand.Int(rand.Reader, big.NewInt(int64(options)))
+		if err != nil {
+			return err
+		}
+		selections[v] = []int{int(n.Int64())}
+	}
+	if err := c.RunVoting(selections); err != nil {
+		return err
+	}
+	if err := c.RunTally(); err != nil {
+		return err
+	}
+	if err := c.RunVerify(); err != nil {
+		fmt.Printf("\nVERIFICATION FAILED: %v\n", err)
+		return err
+	}
+
+	fmt.Println("\n--- ELECTION RESULT ---")
+	result := c.Result()
+	opts := make([]int, 0, len(result))
+	for opt := range result {
+		opts = append(opts, opt)
+	}
+	sort.Ints(opts)
+	for _, opt := range opts {
+		fmt.Printf("  Option %d: %d votes\n", opt, result[opt])
+	}
+	fmt.Printf("\n  Verified transport messages carried: %d\n", c.Bus.Count())
+	fmt.Println("  All parties authenticated via Ed25519 (Rust); channels via X25519 ECDH (Rust).")
+	fmt.Println("  Election integrity: VERIFIED")
+	return nil
+}