github.com/mholt/acmez/v3 v3.1.2: acme.ChallengeTypeTLSALPN01

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01 in pkg:golang/github.com/mholt/acmez/v3@v3.1.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/mholt/acmez/v3@v3.1.2
Demonstrate these symbols/APIs:
  - github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:800c9e9e639dcd4035bcb2302496cd91b7bb68a7b600f6e4c20c542d2f61b812","contract":["acme.ChallengeTypeTLSALPN01 evaluates to \"tls-alpn-01\" according to RFC 8737 §3.","acme.Challenge with Type ChallengeTypeTLSALPN01 serializes to and deserializes from JSON preserving the challenge type and authorization metadata.","acmez.TLSALPN01ChallengeCert generates a TLS certificate with the challenge identifier in DNSNames and an ECDSA P-256 private key.","acmez.TLSALPN01ChallengeCert includes the critical acmeValidation-v1 extension containing the SHA-256 digest of keyAuthorization.","TLS client and server configured with the generated challenge certificate and acmez.ACMETLS1Protocol complete a handshake negotiating \"acme-tls/1\".","TLS client configured with an incompatible ALPN protocol fails to negotiate \"acme-tls/1\" against the challenge server."],"goal":"verify github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01 in pkg:golang/github.com/mholt/acmez/v3@v3.1.2","kind":"HOW","packages":["pkg:golang/github.com/mholt/acmez/v3@v3.1.2"],"schemaVersion":1,"symbols":["github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","executionContext":"go","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/mholt/acmez/v3@v3.1.2"],"schemaVersion":1,"subject":"pkg:golang/github.com/mholt/acmez/v3@v3.1.2","symbols":["github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/mholt/acmez/v3 v3.1.2

require (
	golang.org/x/crypto v0.27.0 // indirect
	golang.org/x/net v0.29.0 // indirect
	golang.org/x/text v0.18.0 // indirect
)

github.com/mholt/acmez/v3 v3.1.2 h1:auob8J/0FhmdClQicvJvuDavgd5ezwLBfKuYmynhYzc=
github.com/mholt/acmez/v3 v3.1.2/go.mod h1:L1wOU06KKvq7tswuMDwKdcHeKpFFgkppZy/y0DFxagQ=
golang.org/x/crypto v0.27.0 h1:GXm2NjJrPaiv/h1tb2UH8QfgC/hOf/+z0p6PT8o1w7A=
golang.org/x/crypto v0.27.0/go.mod h1:1Xngt8kV6Dvbssa53Ziq6Eqn0HqbZi5Z6R0ZpwQzt70=
golang.org/x/net v0.29.0 h1:5ORfpBpCs4HzDYoodCDBbwHzdR5UrLBZ3sOnUJmFoHo=
golang.org/x/net v0.29.0/go.mod h1:gLkgy8jTGERgjzMic6DS9+SP0ajcu6Xu3Orq/SpETg0=
golang.org/x/text v0.18.0 h1:XvMDiNzPAl0jr17s6W9lcaIhGUfUORdGCNsuLmPG224=
golang.org/x/text v0.18.0/go.mod h1:BuEKDfySbSR4drPmRPG/7iBdf8hvFMuRexcpahXilzY=

package main

import (
	"crypto/tls"
	"fmt"
	"log"

	"github.com/mholt/acmez/v3"
	"github.com/mholt/acmez/v3/acme"
)

func main() {
	chal := acme.Challenge{
		Type:             acme.ChallengeTypeTLSALPN01,
		Token:            "dGVzdC10b2tlbg",
		KeyAuthorization: "dGVzdC10b2tlbg.thumbprint123",
		Identifier: acme.Identifier{
			Type:  "dns",
			Value: "example.com",
		},
	}

	fmt.Printf("Challenge Type: %s\n", chal.Type)

	cert, err := acmez.TLSALPN01ChallengeCert(chal)
	if err != nil {
		log.Fatalf("failed to generate TLS-ALPN-01 challenge cert: %v", err)
	}

	tlsConfig := &tls.Config{
		Certificates: []tls.Certificate{*cert},
		NextProtos:   []string{acmez.ACMETLS1Protocol},
	}

	fmt.Printf("Configured TLS ALPN protocol: %s (cert count: %d)\n", tlsConfig.NextProtos[0], len(tlsConfig.Certificates))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01 in pkg:golang/github.com/mholt/acmez/v3@v3.1.2",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/mholt/acmez/v3@v3.1.2"
  ],
  "symbols": [
    "github.com/mholt/acmez/v3/acme.ChallengeTypeTLSALPN01"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package test

import (
	"bytes"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/sha256"
	"crypto/tls"
	"crypto/x509"
	"encoding/asn1"
	"encoding/json"
	"net"
	"testing"
	"time"

	"github.com/mholt/acmez/v3"
	"github.com/mholt/acmez/v3/acme"
)

// idPEACMEIdentifierV1 OID: 1.3.6.1.5.5.7.1.31 (RFC 8737 §6.1)
var idPEACMEIdentifierV1 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 1, 31}

func TestChallengeTypeTLSALPN01Constant(t *testing.T) {
	if acme.ChallengeTypeTLSALPN01 != "tls-alpn-01" {
		t.Fatalf("acme.ChallengeTypeTLSALPN01 = %q, want %q", acme.ChallengeTypeTLSALPN01, "tls-alpn-01")
	}
}

func TestChallengeTypeTLSALPN01Serialization(t *testing.T) {
	chal := acme.Challenge{
		Type:             acme.ChallengeTypeTLSALPN01,
		URL:              "https://example.com/acme/chall/123",
		Status:           "pending",
		Token:            "EVAhDYAs2MyAN-PnwSeAhA",
		KeyAuthorization: "EVAhDYAs2MyAN-PnwSeAhA.TestThumbprintString123",
		Identifier: acme.Identifier{
			Type:  "dns",
			Value: "example.com",
		},
	}

	data, err := json.Marshal(chal)
	if err != nil {
		t.Fatalf("json.Marshal failed: %v", err)
	}

	var parsed map[string]interface{}
	if err := json.Unmarshal(data, &parsed); err != nil {
		t.Fatalf("json.Unmarshal into map failed: %v", err)
	}

	if parsed["type"] != "tls-alpn-01" {
		t.Errorf("expected json type %q, got %v", "tls-alpn-01", parsed["type"])
	}
	if parsed["token"] != "EVAhDYAs2MyAN-PnwSeAhA" {
		t.Errorf("expected token %q, got %v", "EVAhDYAs2MyAN-PnwSeAhA", parsed["token"])
	}

	var roundtrip acme.Challenge
	if err := json.Unmarshal(data, &roundtrip); err != nil {
		t.Fatalf("json.Unmarshal roundtrip failed: %v", err)
	}
	if roundtrip.Type != acme.ChallengeTypeTLSALPN01 {
		t.Errorf("roundtrip.Type = %q, want %q", roundtrip.Type, acme.ChallengeTypeTLSALPN01)
	}
	if roundtrip.KeyAuthorization != chal.KeyAuthorization {
		t.Errorf("roundtrip.KeyAuthorization = %q, want %q", roundtrip.KeyAuthorization, chal.KeyAuthorization)
	}
}

func TestTLSALPN01ChallengeCertProperties(t *testing.T) {
	domain := "example.com"
	keyAuth := "test-token-value.test-account-thumbprint"

	chal := acme.Challenge{
		Type:             acme.ChallengeTypeTLSALPN01,
		Token:            "test-token-value",
		KeyAuthorization: keyAuth,
		Identifier: acme.Identifier{
			Type:  "dns",
			Value: domain,
		},
	}

	tlsCert, err := acmez.TLSALPN01ChallengeCert(chal)
	if err != nil {
		t.Fatalf("TLSALPN01ChallengeCert failed: %v", err)
	}
	if tlsCert == nil || len(tlsCert.Certificate) == 0 {
		t.Fatal("expected non-empty tls.Certificate")
	}

	leaf, err := x509.ParseCertificate(tlsCert.Certificate[0])
	if err != nil {
		t.Fatalf("x509.ParseCertificate failed: %v", err)
	}

	// Verify SAN
	if len(leaf.DNSNames) != 1 || leaf.DNSNames[0] != domain {
		t.Errorf("leaf.DNSNames = %v, want [%s]", leaf.DNSNames, domain)
	}

	// Verify ECDSA P-256 key
	privKey, ok := tlsCert.PrivateKey.(*ecdsa.PrivateKey)
	if !ok {
		t.Fatalf("expected *ecdsa.PrivateKey, got %T", tlsCert.PrivateKey)
	}
	if privKey.Curve != elliptic.P256() {
		t.Errorf("expected elliptic.P256 curve, got %v", privKey.Curve.Params().Name)
	}

	// Verify acmeValidation-v1 extension
	expectedDigest := sha256.Sum256([]byte(keyAuth))
	var foundExt bool
	for _, ext := range leaf.Extensions {
		if ext.Id.Equal(idPEACMEIdentifierV1) {
			foundExt = true
			if !ext.Critical {
				t.Errorf("expected idPEACMEIdentifierV1 extension to be marked critical")
			}
			var val []byte
			if rest, err := asn1.Unmarshal(ext.Value, &val); err != nil || len(rest) > 0 {
				t.Fatalf("failed to unmarshal extension ASN.1 value: %v", err)
			}
			if !bytes.Equal(val, expectedDigest[:]) {
				t.Errorf("extension digest mismatch: got %x, want %x", val, expectedDigest[:])
			}
			break
		}
	}
	if !foundExt {
		t.Errorf("critical acmeValidation-v1 extension (%v) not found in certificate", idPEACMEIdentifierV1)
	}
}

func TestTLSALPN01Handshake(t *testing.T) {
	domain := "example.com"
	keyAuth := "handshake-token.handshake-thumbprint"

	chal := acme.Challenge{
		Type:             acme.ChallengeTypeTLSALPN01,
		Token:            "handshake-token",
		KeyAuthorization: keyAuth,
		Identifier: acme.Identifier{
			Type:  "dns",
			Value: domain,
		},
	}

	tlsCert, err := acmez.TLSALPN01ChallengeCert(chal)
	if err != nil {
		t.Fatalf("TLSALPN01ChallengeCert failed: %v", err)
	}

	serverConfig := &tls.Config{
		Certificates: []tls.Certificate{*tlsCert},
		NextProtos:   []string{acmez.ACMETLS1Protocol},
	}

	clientConfig := &tls.Config{
		InsecureSkipVerify: true,
		ServerName:         domain,
		NextProtos:         []string{acmez.ACMETLS1Protocol},
	}

	clientConn, serverConn := net.Pipe()
	defer clientConn.Close()
	defer serverConn.Close()

	tlsServer := tls.Server(serverConn, serverConfig)
	tlsClient := tls.Client(clientConn, clientConfig)

	errChan := make(chan error, 2)

	go func() {
		errChan <- tlsServer.Handshake()
	}()

	go func() {
		errChan <- tlsClient.Handshake()
	}()

	for i := 0; i < 2; i++ {
		select {
		case err := <-errChan:
			if err != nil {
				t.Fatalf("handshake failed: %v", err)
			}
		case <-time.After(5 * time.Second):
			t.Fatal("handshake timed out")
		}
	}

	clientState := tlsClient.ConnectionState()
	if clientState.NegotiatedProtocol != acmez.ACMETLS1Protocol {
		t.Errorf("client NegotiatedProtocol = %q, want %q", clientState.NegotiatedProtocol, acmez.ACMETLS1Protocol)
	}
	serverState := tlsServer.ConnectionState()
	if serverState.NegotiatedProtocol != acmez.ACMETLS1Protocol {
		t.Errorf("server NegotiatedProtocol = %q, want %q", serverState.NegotiatedProtocol, acmez.ACMETLS1Protocol)
	}
}

func TestTLSALPN01ProtocolNegotiationMismatch(t *testing.T) {
	chal := acme.Challenge{
		Type:             acme.ChallengeTypeTLSALPN01,
		Token:            "mismatch-token",
		KeyAuthorization: "mismatch-token.thumbprint",
		Identifier: acme.Identifier{
			Type:  "dns",
			Value: "example.com",
		},
	}

	tlsCert, err := acmez.TLSALPN01ChallengeCert(chal)
	if err != nil {
		t.Fatalf("TLSALPN01ChallengeCert failed: %v", err)
	}

	serverConfig := &tls.Config{
		Certificates: []tls.Certificate{*tlsCert},
		NextProtos:   []string{acmez.ACMETLS1Protocol},
	}

	clientConfig := &tls.Config{
		InsecureSkipVerify: true,
		ServerName:         "example.com",
		NextProtos:         []string{"http/1.1"},
	}

	clientConn, serverConn := net.Pipe()
	defer clientConn.Close()
	defer serverConn.Close()

	tlsServer := tls.Server(serverConn, serverConfig)
	tlsClient := tls.Client(clientConn, clientConfig)

	errChan := make(chan error, 2)
	go func() {
		errChan <- tlsServer.Handshake()
	}()
	go func() {
		errChan <- tlsClient.Handshake()
	}()

	for i := 0; i < 2; i++ {
		select {
		case err := <-errChan:
			if err != nil {
				// Handshake error is acceptable on protocol mismatch
				return
			}
		case <-time.After(5 * time.Second):
			t.Fatal("handshake timed out")
		}
	}

	if tlsClient.ConnectionState().NegotiatedProtocol == acmez.ACMETLS1Protocol {
		t.Errorf("did not expect client to negotiate %q when only offering http/1.1", acmez.ACMETLS1Protocol)
	}
}