Add initial support for yubikey.
Mariano Cano
4 years ago
parent
9f1d95d8bf
commit
6868190fff
@ -0,0 +1,289 @@
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package main
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import (
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"context"
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"crypto"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rand"
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"crypto/sha1"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/pem"
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"flag"
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"fmt"
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"math/big"
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"os"
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"time"
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"github.com/pkg/errors"
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"github.com/smallstep/certificates/kms/apiv1"
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"github.com/smallstep/certificates/kms/yubikey"
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"github.com/smallstep/cli/crypto/pemutil"
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"github.com/smallstep/cli/ui"
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"github.com/smallstep/cli/utils"
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)
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type Config struct {
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RootOnly bool
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RootSlot string
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CrtSlot string
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RootFile string
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KeyFile string
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Pin string
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}
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func (c *Config) Validate() error {
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switch {
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case c.RootFile != "" && c.KeyFile == "":
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return errors.New("flag `--root` requires flag `--key`")
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case c.KeyFile != "" && c.RootFile == "":
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return errors.New("flag `--key` requires flag `--root`")
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case c.RootOnly && c.RootFile != "":
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return errors.New("flag `--root-only` is incompatible with flag `--root`")
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case c.RootSlot == c.CrtSlot:
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return errors.New("flat `--root-slot` and flag `--crt-slot` cannot be the same")
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default:
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return nil
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}
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}
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func main() {
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var c Config
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flag.BoolVar(&c.RootOnly, "root-only", false, "Slot only the root certificate and sign and intermediate.")
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flag.StringVar(&c.RootSlot, "root-slot", "9a", "Slot to store the root certificate.")
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flag.StringVar(&c.CrtSlot, "crt-slot", "9c", "Slot to store the intermediate certificate.")
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flag.StringVar(&c.RootFile, "root", "", "Path to the root certificate to use.")
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flag.StringVar(&c.KeyFile, "key", "", "Path to the root key to use.")
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flag.Usage = usage
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flag.Parse()
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if err := c.Validate(); err != nil {
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fatal(err)
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}
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pin, err := ui.PromptPassword("What is the YubiKey PIN?")
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if err != nil {
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fatal(err)
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}
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c.Pin = string(pin)
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k, err := yubikey.New(context.Background(), apiv1.Options{
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Type: string(apiv1.YubiKey),
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Pin: c.Pin,
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})
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if err != nil {
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fatal(err)
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}
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if err := createPKI(k, c); err != nil {
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fatal(err)
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}
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defer func() {
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_ = k.Close()
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}()
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}
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func fatal(err error) {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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func usage() {
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fmt.Fprintln(os.Stderr, "Usage: step-yubikey-init")
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fmt.Fprintln(os.Stderr, `
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The step-yubikey-init command initializes a public key infrastructure (PKI)
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to be used by step-ca.
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This tool is experimental and in the future it will be integrated in step cli.
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OPTIONS`)
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fmt.Fprintln(os.Stderr)
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flag.PrintDefaults()
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fmt.Fprintln(os.Stderr, `
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COPYRIGHT
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(c) 2018-2020 Smallstep Labs, Inc.`)
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os.Exit(1)
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}
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func createPKI(k *yubikey.YubiKey, c Config) error {
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var err error
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ui.Println("Creating PKI ...")
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now := time.Now()
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// Root Certificate
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var signer crypto.Signer
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var root *x509.Certificate
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if c.RootFile != "" && c.KeyFile != "" {
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root, err = pemutil.ReadCertificate(c.RootFile)
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if err != nil {
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return err
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}
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key, err := pemutil.Read(c.KeyFile)
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if err != nil {
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return err
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}
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var ok bool
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if signer, ok = key.(crypto.Signer); !ok {
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return errors.Errorf("key type '%T' does not implement a signer", key)
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}
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} else {
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resp, err := k.CreateKey(&apiv1.CreateKeyRequest{
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Name: c.RootSlot,
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SignatureAlgorithm: apiv1.ECDSAWithSHA256,
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})
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if err != nil {
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return err
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}
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signer, err = k.CreateSigner(&resp.CreateSignerRequest)
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if err != nil {
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return err
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}
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template := &x509.Certificate{
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IsCA: true,
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NotBefore: now,
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NotAfter: now.Add(time.Hour * 24 * 365 * 10),
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KeyUsage: x509.KeyUsageCertSign | x509.KeyUsageCRLSign,
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BasicConstraintsValid: true,
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MaxPathLen: 1,
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MaxPathLenZero: false,
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Issuer: pkix.Name{CommonName: "YubiKey Smallstep Root"},
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Subject: pkix.Name{CommonName: "YubiKey Smallstep Root"},
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SerialNumber: mustSerialNumber(),
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SubjectKeyId: mustSubjectKeyID(resp.PublicKey),
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}
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b, err := x509.CreateCertificate(rand.Reader, template, template, resp.PublicKey, signer)
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if err != nil {
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return err
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}
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root, err = x509.ParseCertificate(b)
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if err != nil {
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return errors.Wrap(err, "error parsing root certificate")
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}
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if err = k.StoreCertificate(&apiv1.StoreCertificateRequest{
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Name: c.RootSlot,
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Certificate: root,
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}); err != nil {
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return err
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}
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if err = utils.WriteFile("root_ca.crt", pem.EncodeToMemory(&pem.Block{
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Type: "CERTIFICATE",
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Bytes: b,
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}), 0600); err != nil {
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return err
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}
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ui.PrintSelected("Root Key", "yubikey:slot-id="+resp.Name)
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ui.PrintSelected("Root Certificate", "root_ca.crt")
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}
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// Intermediate Certificate
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var keyName string
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var publicKey crypto.PublicKey
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if c.RootOnly {
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priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
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if err != nil {
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return errors.Wrap(err, "error creating intermediate public key")
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}
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pass, err := ui.PromptPasswordGenerate("What do you want your password to be? [leave empty and we'll generate one]",
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ui.WithRichPrompt())
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if err != nil {
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return err
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}
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_, err = pemutil.Serialize(priv, pemutil.WithPassword(pass), pemutil.ToFile("intermediate_ca_key", 0600))
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if err != nil {
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return err
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}
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publicKey = priv.Public()
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} else {
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resp, err := k.CreateKey(&apiv1.CreateKeyRequest{
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Name: c.CrtSlot,
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SignatureAlgorithm: apiv1.ECDSAWithSHA256,
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})
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if err != nil {
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return err
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}
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publicKey = resp.PublicKey
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keyName = resp.Name
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}
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template := &x509.Certificate{
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IsCA: true,
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NotBefore: now,
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NotAfter: now.Add(time.Hour * 24 * 365 * 10),
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KeyUsage: x509.KeyUsageCertSign | x509.KeyUsageCRLSign,
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BasicConstraintsValid: true,
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MaxPathLen: 0,
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MaxPathLenZero: true,
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Issuer: root.Subject,
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Subject: pkix.Name{CommonName: "YubiKey Smallstep Intermediate"},
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SerialNumber: mustSerialNumber(),
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SubjectKeyId: mustSubjectKeyID(publicKey),
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}
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b, err := x509.CreateCertificate(rand.Reader, template, root, publicKey, signer)
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if err != nil {
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return err
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}
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intermediate, err := x509.ParseCertificate(b)
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if err != nil {
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return errors.Wrap(err, "error parsing intermediate certificate")
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}
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if err = k.StoreCertificate(&apiv1.StoreCertificateRequest{
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Name: c.CrtSlot,
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Certificate: intermediate,
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}); err != nil {
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return err
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}
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if err = utils.WriteFile("intermediate_ca.crt", pem.EncodeToMemory(&pem.Block{
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Type: "CERTIFICATE",
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Bytes: b,
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}), 0600); err != nil {
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return err
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}
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if c.RootOnly {
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ui.PrintSelected("Intermediate Key", "intermediate_ca_key")
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} else {
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ui.PrintSelected("Intermediate Key", "yubikey:slot-id="+keyName)
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}
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ui.PrintSelected("Intermediate Certificate", "intermediate_ca.crt")
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return nil
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}
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func mustSerialNumber() *big.Int {
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serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
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sn, err := rand.Int(rand.Reader, serialNumberLimit)
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if err != nil {
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panic(err)
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}
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return sn
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}
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func mustSubjectKeyID(key crypto.PublicKey) []byte {
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b, err := x509.MarshalPKIXPublicKey(key)
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if err != nil {
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panic(err)
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}
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hash := sha1.Sum(b)
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return hash[:]
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}
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@ -0,0 +1,244 @@
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package yubikey
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import (
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"context"
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"crypto"
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"crypto/x509"
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"net/url"
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"strings"
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"github.com/go-piv/piv-go/piv"
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"github.com/pkg/errors"
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"github.com/smallstep/certificates/kms/apiv1"
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)
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// YubiKey implements the KMS interface on a YubiKey.
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type YubiKey struct {
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yk *piv.YubiKey
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pin string
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}
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// New initializes a new YubiKey.
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// TODO(mariano): only one card is currently supported.
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func New(ctx context.Context, opts apiv1.Options) (*YubiKey, error) {
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cards, err := piv.Cards()
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if err != nil {
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return nil, err
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}
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if len(cards) == 0 {
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return nil, errors.New("error detecting yubikey")
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}
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yk, err := piv.Open(cards[0])
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if err != nil {
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return nil, errors.Wrap(err, "error opening yubikey")
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}
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return &YubiKey{
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yk: yk,
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pin: opts.Pin,
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}, nil
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}
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// LoadCertificate implements kms.CertificateManager and loads a certificate
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// from the YubiKey.
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func (k *YubiKey) LoadCertificate(req *apiv1.LoadCertificateRequest) (*x509.Certificate, error) {
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slot, err := getSlot(req.Name)
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if err != nil {
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return nil, err
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}
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cert, err := k.yk.Certificate(slot)
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if err != nil {
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return nil, errors.Wrap(err, "error retrieving certificate")
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}
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return cert, nil
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}
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// StoreCertificate implements kms.CertificateManager and stores a certificate
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// in the YubiKey.
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func (k *YubiKey) StoreCertificate(req *apiv1.StoreCertificateRequest) error {
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if req.Certificate == nil {
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return errors.New("storeCertificateRequest 'Certificate' cannot be nil")
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}
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slot, err := getSlot(req.Name)
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if err != nil {
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return err
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}
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err = k.yk.SetCertificate(piv.DefaultManagementKey, slot, req.Certificate)
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if err != nil {
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return errors.Wrap(err, "error storing certificate")
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}
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return nil
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}
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// GetPublicKey returns the public key present in the YubiKey signature slot.
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func (k *YubiKey) GetPublicKey(req *apiv1.GetPublicKeyRequest) (crypto.PublicKey, error) {
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slot, err := getSlot(req.Name)
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if err != nil {
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return nil, err
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}
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cert, err := k.yk.Certificate(slot)
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if err != nil {
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return nil, errors.Wrap(err, "error retrieving certificate")
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}
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return cert.PublicKey, nil
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}
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// CreateKey generates a new key in the YubiKey and returns the public key.
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func (k *YubiKey) CreateKey(req *apiv1.CreateKeyRequest) (*apiv1.CreateKeyResponse, error) {
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alg, err := getSignatureAlgorithm(req.SignatureAlgorithm, req.Bits)
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if err != nil {
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return nil, err
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}
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slot, name, err := getSlotAndName(req.Name)
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if err != nil {
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return nil, err
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}
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pub, err := k.yk.GenerateKey(piv.DefaultManagementKey, slot, piv.Key{
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Algorithm: alg,
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PINPolicy: piv.PINPolicyAlways,
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TouchPolicy: piv.TouchPolicyNever,
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})
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if err != nil {
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return nil, errors.Wrap(err, "error generating key")
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}
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return &apiv1.CreateKeyResponse{
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Name: name,
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PublicKey: pub,
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CreateSignerRequest: apiv1.CreateSignerRequest{
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SigningKey: name,
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},
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}, nil
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}
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// CreateSigner creates a signer using the key present in the YubiKey signature
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// slot.
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func (k *YubiKey) CreateSigner(req *apiv1.CreateSignerRequest) (crypto.Signer, error) {
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slot, err := getSlot(req.SigningKey)
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if err != nil {
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return nil, err
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}
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cert, err := k.yk.Certificate(slot)
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if err != nil {
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return nil, errors.Wrap(err, "error retrieving certificate")
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}
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priv, err := k.yk.PrivateKey(slot, cert.PublicKey, piv.KeyAuth{
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PIN: k.pin,
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})
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if err != nil {
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return nil, errors.Wrap(err, "error retrieving private key")
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}
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signer, ok := priv.(crypto.Signer)
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if !ok {
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return nil, errors.New("private key is not a crypto.Signer")
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}
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return signer, nil
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}
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// Close releases the connection to the YubiKey.
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func (k *YubiKey) Close() error {
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return errors.Wrap(k.yk.Close(), "error closing yubikey")
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}
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// signatureAlgorithmMapping is a mapping between the step signature algorithm,
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// and bits for RSA keys, with yubikey ones.
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var signatureAlgorithmMapping = map[apiv1.SignatureAlgorithm]interface{}{
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apiv1.UnspecifiedSignAlgorithm: piv.AlgorithmEC256,
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apiv1.SHA256WithRSA: map[int]piv.Algorithm{
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0: piv.AlgorithmRSA2048,
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1024: piv.AlgorithmRSA1024,
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2048: piv.AlgorithmRSA2048,
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},
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apiv1.SHA512WithRSA: map[int]piv.Algorithm{
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0: piv.AlgorithmRSA2048,
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1024: piv.AlgorithmRSA1024,
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2048: piv.AlgorithmRSA2048,
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},
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apiv1.SHA256WithRSAPSS: map[int]piv.Algorithm{
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0: piv.AlgorithmRSA2048,
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1024: piv.AlgorithmRSA1024,
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2048: piv.AlgorithmRSA2048,
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},
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apiv1.SHA512WithRSAPSS: map[int]piv.Algorithm{
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0: piv.AlgorithmRSA2048,
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1024: piv.AlgorithmRSA1024,
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2048: piv.AlgorithmRSA2048,
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},
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apiv1.ECDSAWithSHA256: piv.AlgorithmEC256,
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apiv1.ECDSAWithSHA384: piv.AlgorithmEC384,
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}
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func getSignatureAlgorithm(alg apiv1.SignatureAlgorithm, bits int) (piv.Algorithm, error) {
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v, ok := signatureAlgorithmMapping[alg]
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if !ok {
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return 0, errors.Errorf("YubiKey does not support signature algorithm '%s'", alg)
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}
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switch v := v.(type) {
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case piv.Algorithm:
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return v, nil
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case map[int]piv.Algorithm:
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signatureAlgorithm, ok := v[bits]
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if !ok {
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return 0, errors.Errorf("YubiKey does not support signature algorithm '%s' with '%d' bits", alg, bits)
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}
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return signatureAlgorithm, nil
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default:
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return 0, errors.Errorf("unexpected error: this should not happen")
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}
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}
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var slotMapping = map[string]piv.Slot{
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"9a": piv.SlotAuthentication,
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"9c": piv.SlotSignature,
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"9e": piv.SlotCardAuthentication,
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"9d": piv.SlotKeyManagement,
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}
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func getSlot(name string) (piv.Slot, error) {
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slot, _, err := getSlotAndName(name)
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return slot, err
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}
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func getSlotAndName(name string) (piv.Slot, string, error) {
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if name == "" {
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return piv.SlotSignature, "yubikey:slot-id=9c", nil
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}
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var slotID string
|
||||
name = strings.ToLower(name)
|
||||
if strings.HasPrefix(name, "yubikey:") {
|
||||
u, err := url.Parse(name)
|
||||
if err != nil {
|
||||
return piv.Slot{}, "", errors.Wrapf(err, "error parsing '%s'", name)
|
||||
}
|
||||
v, err := url.ParseQuery(u.Opaque)
|
||||
if err != nil {
|
||||
return piv.Slot{}, "", errors.Wrapf(err, "error parsing '%s'", name)
|
||||
}
|
||||
if slotID = v.Get("slot-id"); slotID == "" {
|
||||
return piv.Slot{}, "", errors.Wrapf(err, "error parsing '%s': slot-id is missing", name)
|
||||
}
|
||||
} else {
|
||||
slotID = name
|
||||
}
|
||||
|
||||
s, ok := slotMapping[slotID]
|
||||
if !ok {
|
||||
return piv.Slot{}, "", errors.Errorf("usupported slot-id '%s'", name)
|
||||
}
|
||||
|
||||
name = "yubikey:slot-id=" + url.QueryEscape(slotID)
|
||||
return s, name, nil
|
||||
}
|
||||
Loading…
Reference in New Issue