134 lines
3.7 KiB
Go
134 lines
3.7 KiB
Go
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
|
|
}
|