1
package pki
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3
import (
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	"bytes"
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	"crypto/ed25519"
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	"crypto/rand"
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	"crypto/tls"
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	"crypto/x509"
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	"crypto/x509/pkix"
10
	"encoding/pem"
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	"fmt"
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	"math/big"
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	"time"
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15
	"go.uber.org/zap"
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)
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const (
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	HashcashDifficulty int           = 18
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	HashcashExpires    time.Duration = time.Second * 10
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	// DefaultCertValidity is the default validity duration for client certificates.
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	DefaultCertValidity time.Duration = time.Hour * 24 * 365 * 5 // 5 years
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)
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type IdentityRequest struct {
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	PublicKey []byte
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	Subject   pkix.Name
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	// ValidFor specifies the certificate validity duration.
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	// If zero, defaults to DefaultCertValidity.
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	ValidFor time.Duration
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}
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func GenerateCertificate(logger *zap.Logger, ca tls.Certificate, req IdentityRequest) (derBytes []byte, err error) {
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	if len(req.PublicKey) != ed25519.PublicKeySize {
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		err = fmt.Errorf("pki: public key is not ed25519")
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		return
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	}
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	caCert, err := x509.ParseCertificate(ca.Certificate[0])
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	if err != nil {
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		err = fmt.Errorf("pki: failed to parse client ca: %w", err)
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		return
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	}
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	sn, err := rand.Int(rand.Reader, max)
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	if err != nil {
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		err = fmt.Errorf("pki: failed to generate certificate serial: %w", err)
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		return
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	}
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	now := time.Now()
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	validFor := DefaultCertValidity
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	if req.ValidFor > 0 {
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		validFor = req.ValidFor
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	}
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	notAfter := now.Add(validFor)
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	cert := &x509.Certificate{
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		SerialNumber:          sn,
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		Subject:               req.Subject,
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		NotBefore:             now,
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		NotAfter:              notAfter,
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		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
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		KeyUsage:              x509.KeyUsageDigitalSignature,
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		BasicConstraintsValid: true,
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		IsCA:                  false,
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	}
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	certBytes, err := x509.CreateCertificate(rand.Reader, cert, caCert, ed25519.PublicKey(req.PublicKey), ca.PrivateKey)
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	if err != nil {
73
		err = fmt.Errorf("pki: failed to generate client certificate: %w", err)
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		return
75
	}
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	logger.Info("New client certificate issued", zap.String("commonName", req.Subject.CommonName))
78
 
79
	return certBytes, nil
80
}
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func GeneratePrivKey() (privKey ed25519.PublicKey, keyPem string) {
83
	certPubKey, certPrivKey, err := ed25519.GenerateKey(rand.Reader)
84
	if err != nil {
85
		panic(err)
86
	}
87
 
88
	x509PrivKey, err := x509.MarshalPKCS8PrivateKey(certPrivKey)
89
	if err != nil {
90
		panic(err)
91
	}
92
 
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	certPrivKeyPEM := new(bytes.Buffer)
94
	pem.Encode(certPrivKeyPEM, &pem.Block{
95
		Type:  "PRIVATE KEY",
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		Bytes: x509PrivKey,
97
	})
98
 
99
	return certPubKey, certPrivKeyPEM.String()
100
}
101
 
102
var (
103
	max = new(big.Int)
104
)
105
 
106
func init() {
107
	max.Exp(big.NewInt(2), big.NewInt(130), nil).Sub(max, big.NewInt(1))
108
}