1package quic
2
3import (
4 "crypto/ed25519"
5 "crypto/rand"
6 "crypto/sha256"
7 "crypto/tls"
8 "crypto/x509"
9 "crypto/x509/pkix"
10 "encoding/pem"
11 "math/big"
12 "time"
13)
14
15// Ephemeral certificates are minted per bootstrap listener and never
16// persisted: the SHA-256 pin travels through the SSH bootstrap channel,
17// and the key dies with the process.
18
19// GenerateEphemeralCert mints one self-signed Ed25519 certificate valid
20// for 24 hours. The returned fingerprint is the SHA-256 of the raw DER
21// certificate the dialer pins.
22func GenerateEphemeralCert() (tls.Certificate, []byte, error) {
23 public, private, err := ed25519.GenerateKey(rand.Reader)
24 if err != nil {
25 return tls.Certificate{}, nil, err
26 }
27 serial, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
28 if err != nil {
29 return tls.Certificate{}, nil, err
30 }
31 now := time.Now()
32 template := &x509.Certificate{
33 SerialNumber: serial,
34 Subject: pkix.Name{CommonName: "vev-ephemeral"},
35 NotBefore: now.Add(-time.Minute),
36 NotAfter: now.Add(24 * time.Hour),
37 KeyUsage: x509.KeyUsageDigitalSignature,
38 ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
39 DNSNames: []string{"vev-bootstrap"},
40 }
41 der, err := x509.CreateCertificate(rand.Reader, template, template, public, private)
42 if err != nil {
43 return tls.Certificate{}, nil, err
44 }
45 cert, err := tls.X509KeyPair(
46 pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der}),
47 pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: mustMarshalPKCS8(private)}),
48 )
49 if err != nil {
50 return tls.Certificate{}, nil, err
51 }
52 sum := sha256.Sum256(der)
53 return cert, sum[:], nil
54}
55
56// mustMarshalPKCS8 marshals an Ed25519 private key; Ed25519 keys always
57// marshal, so a failure panics as a programming error.
58func mustMarshalPKCS8(private ed25519.PrivateKey) []byte {
59 der, err := x509.MarshalPKCS8PrivateKey(private)
60 if err != nil {
61 panic(err)
62 }
63 return der
64}
65
66// FingerprintDER returns the SHA-256 pin of one DER certificate.
67func FingerprintDER(der []byte) []byte {
68 sum := sha256.Sum256(der)
69 return sum[:]
70}