Support webauthn (#17957)

Migrate from U2F to Webauthn

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

vendor/github.com/cloudflare/cfssl/helpers/derhelpers/ed25519.go

@@ -0,0 +1,133 @@
+package derhelpers
+
+import (
+	"crypto"
+	"crypto/x509/pkix"
+	"encoding/asn1"
+	"errors"
+
+	"golang.org/x/crypto/ed25519"
+)
+
+var errEd25519WrongID = errors.New("incorrect object identifier")
+var errEd25519WrongKeyType = errors.New("incorrect key type")
+
+// ed25519OID is the OID for the Ed25519 signature scheme: see
+// https://datatracker.ietf.org/doc/draft-ietf-curdle-pkix-04.
+var ed25519OID = asn1.ObjectIdentifier{1, 3, 101, 112}
+
+// subjectPublicKeyInfo reflects the ASN.1 object defined in the X.509 standard.
+//
+// This is defined in crypto/x509 as "publicKeyInfo".
+type subjectPublicKeyInfo struct {
+	Algorithm pkix.AlgorithmIdentifier
+	PublicKey asn1.BitString
+}
+
+// MarshalEd25519PublicKey creates a DER-encoded SubjectPublicKeyInfo for an
+// ed25519 public key, as defined in
+// https://tools.ietf.org/html/draft-ietf-curdle-pkix-04. This is analagous to
+// MarshalPKIXPublicKey in crypto/x509, which doesn't currently support Ed25519.
+func MarshalEd25519PublicKey(pk crypto.PublicKey) ([]byte, error) {
+	pub, ok := pk.(ed25519.PublicKey)
+	if !ok {
+		return nil, errEd25519WrongKeyType
+	}
+
+	spki := subjectPublicKeyInfo{
+		Algorithm: pkix.AlgorithmIdentifier{
+			Algorithm: ed25519OID,
+		},
+		PublicKey: asn1.BitString{
+			BitLength: len(pub) * 8,
+			Bytes:     pub,
+		},
+	}
+
+	return asn1.Marshal(spki)
+}
+
+// ParseEd25519PublicKey returns the Ed25519 public key encoded by the input.
+func ParseEd25519PublicKey(der []byte) (crypto.PublicKey, error) {
+	var spki subjectPublicKeyInfo
+	if rest, err := asn1.Unmarshal(der, &spki); err != nil {
+		return nil, err
+	} else if len(rest) > 0 {
+		return nil, errors.New("SubjectPublicKeyInfo too long")
+	}
+
+	if !spki.Algorithm.Algorithm.Equal(ed25519OID) {
+		return nil, errEd25519WrongID
+	}
+
+	if spki.PublicKey.BitLength != ed25519.PublicKeySize*8 {
+		return nil, errors.New("SubjectPublicKeyInfo PublicKey length mismatch")
+	}
+
+	return ed25519.PublicKey(spki.PublicKey.Bytes), nil
+}
+
+// oneAsymmetricKey reflects the ASN.1 structure for storing private keys in
+// https://tools.ietf.org/html/draft-ietf-curdle-pkix-04, excluding the optional
+// fields, which we don't use here.
+//
+// This is identical to pkcs8 in crypto/x509.
+type oneAsymmetricKey struct {
+	Version    int
+	Algorithm  pkix.AlgorithmIdentifier
+	PrivateKey []byte
+}
+
+// curvePrivateKey is the innter type of the PrivateKey field of
+// oneAsymmetricKey.
+type curvePrivateKey []byte
+
+// MarshalEd25519PrivateKey returns a DER encdoing of the input private key as
+// specified in https://tools.ietf.org/html/draft-ietf-curdle-pkix-04.
+func MarshalEd25519PrivateKey(sk crypto.PrivateKey) ([]byte, error) {
+	priv, ok := sk.(ed25519.PrivateKey)
+	if !ok {
+		return nil, errEd25519WrongKeyType
+	}
+
+	// Marshal the innter CurvePrivateKey.
+	curvePrivateKey, err := asn1.Marshal(priv.Seed())
+	if err != nil {
+		return nil, err
+	}
+
+	// Marshal the OneAsymmetricKey.
+	asym := oneAsymmetricKey{
+		Version: 0,
+		Algorithm: pkix.AlgorithmIdentifier{
+			Algorithm: ed25519OID,
+		},
+		PrivateKey: curvePrivateKey,
+	}
+	return asn1.Marshal(asym)
+}
+
+// ParseEd25519PrivateKey returns the Ed25519 private key encoded by the input.
+func ParseEd25519PrivateKey(der []byte) (crypto.PrivateKey, error) {
+	asym := new(oneAsymmetricKey)
+	if rest, err := asn1.Unmarshal(der, asym); err != nil {
+		return nil, err
+	} else if len(rest) > 0 {
+		return nil, errors.New("OneAsymmetricKey too long")
+	}
+
+	// Check that the key type is correct.
+	if !asym.Algorithm.Algorithm.Equal(ed25519OID) {
+		return nil, errEd25519WrongID
+	}
+
+	// Unmarshal the inner CurvePrivateKey.
+	seed := new(curvePrivateKey)
+	if rest, err := asn1.Unmarshal(asym.PrivateKey, seed); err != nil {
+		return nil, err
+	} else if len(rest) > 0 {
+		return nil, errors.New("CurvePrivateKey too long")
+	}
+
+	return ed25519.NewKeyFromSeed(*seed), nil
+}