mirror of
https://github.com/smallstep/certificates.git
synced 2024-10-31 03:20:16 +00:00
303 lines
8.0 KiB
Go
303 lines
8.0 KiB
Go
// +build cgo
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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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"encoding/hex"
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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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managementKey [24]byte
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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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managementKey := piv.DefaultManagementKey
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if opts.ManagementKey != "" {
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b, err := hex.DecodeString(opts.ManagementKey)
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if err != nil {
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return nil, errors.Wrap(err, "error decoding managementKey")
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}
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if len(b) != 24 {
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return nil, errors.New("invalid managementKey: length is not 24 bytes")
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}
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copy(managementKey[:], b[:24])
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}
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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: try removing and reconnecting the device")
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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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managementKey: managementKey,
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}, nil
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}
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func init() {
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apiv1.Register(apiv1.YubiKey, func(ctx context.Context, opts apiv1.Options) (apiv1.KeyManager, error) {
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return New(ctx, opts)
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})
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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(k.managementKey, 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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pub, err := k.getPublicKey(slot)
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if err != nil {
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return nil, err
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}
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return pub, 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(k.managementKey, 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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pub, err := k.getPublicKey(slot)
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if err != nil {
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return nil, err
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}
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priv, err := k.yk.PrivateKey(slot, pub, piv.KeyAuth{
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PIN: k.pin,
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PINPolicy: piv.PINPolicyAlways,
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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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// getPublicKey returns the public key on a slot. First it attempts to do
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// attestation to get a certificate with the public key in it, if this succeeds
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// means that the key was generated in the device. If not we'll try to get the
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// key from a stored certificate in the same slot.
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func (k *YubiKey) getPublicKey(slot piv.Slot) (crypto.PublicKey, error) {
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cert, err := k.yk.Attest(slot)
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if err != nil {
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if cert, err = k.yk.Certificate(slot); err != nil {
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return nil, errors.Wrap(err, "error retrieving public key")
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}
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}
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return cert.PublicKey, nil
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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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"82": {Key: 0x82, Object: 0x5FC10D},
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"83": {Key: 0x83, Object: 0x5FC10E},
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"84": {Key: 0x84, Object: 0x5FC10F},
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"85": {Key: 0x85, Object: 0x5FC110},
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"86": {Key: 0x86, Object: 0x5FC111},
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"87": {Key: 0x87, Object: 0x5FC112},
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"88": {Key: 0x88, Object: 0x5FC113},
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"89": {Key: 0x89, Object: 0x5FC114},
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"8a": {Key: 0x8a, Object: 0x5FC115},
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"8b": {Key: 0x8b, Object: 0x5FC116},
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"8c": {Key: 0x8c, Object: 0x5FC117},
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"8d": {Key: 0x8d, Object: 0x5FC118},
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"8e": {Key: 0x8e, Object: 0x5FC119},
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"8f": {Key: 0x8f, Object: 0x5FC11A},
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"90": {Key: 0x90, Object: 0x5FC11B},
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"91": {Key: 0x91, Object: 0x5FC11C},
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"92": {Key: 0x92, Object: 0x5FC11D},
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"93": {Key: 0x93, Object: 0x5FC11E},
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"94": {Key: 0x94, Object: 0x5FC11F},
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"95": {Key: 0x95, Object: 0x5FC120},
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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
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name = strings.ToLower(name)
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if strings.HasPrefix(name, "yubikey:") {
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u, err := url.Parse(name)
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if err != nil {
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return piv.Slot{}, "", errors.Wrapf(err, "error parsing '%s'", name)
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}
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v, err := url.ParseQuery(u.Opaque)
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if err != nil {
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return piv.Slot{}, "", errors.Wrapf(err, "error parsing '%s'", name)
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}
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if slotID = v.Get("slot-id"); slotID == "" {
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return piv.Slot{}, "", errors.Wrapf(err, "error parsing '%s': slot-id is missing", name)
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}
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} else {
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slotID = name
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}
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s, ok := slotMapping[slotID]
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if !ok {
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return piv.Slot{}, "", errors.Errorf("usupported slot-id '%s'", name)
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}
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name = "yubikey:slot-id=" + url.QueryEscape(slotID)
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return s, name, nil
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}
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