ed25519: support Go 1.13 (#36)

ed25519.go

@@ -0,0 +1,85 @@
+// +build go1.13
+
+package jwt
+
+import (
+	"crypto/ed25519"
+	"errors"
+
+	"github.com/gbrlsnchs/jwt/v3/internal"
+)
+
+var (
+	// ErrEd25519PrivKey is the error for trying to sign a JWT with a nil private key.
+	ErrEd25519PrivKey = errors.New("jwt: Ed25519 private key is nil")
+	// ErrEd25519PubKey is the error for trying to verify a JWT with a nil public key.
+	ErrEd25519PubKey = errors.New("jwt: Ed25519 public key is nil")
+	// ErrEd25519Verification is the error for when verification with Ed25519 fails.
+	ErrEd25519Verification = errors.New("jwt: Ed25519 verification failed")
+
+	_ Algorithm = new(Ed25519)
+)
+
+// Ed25519PrivateKey is an option to set a private key to the Ed25519 algorithm.
+func Ed25519PrivateKey(priv ed25519.PrivateKey) func(*Ed25519) {
+	return func(ed *Ed25519) {
+		ed.priv = priv
+	}
+}
+
+// Ed25519PublicKey is an option to set a public key to the Ed25519 algorithm.
+func Ed25519PublicKey(pub ed25519.PublicKey) func(*Ed25519) {
+	return func(ed *Ed25519) {
+		ed.pub = pub
+	}
+}
+
+// Ed25519 is an algorithm that uses EdDSA to sign SHA-512 hashes.
+type Ed25519 struct {
+	priv ed25519.PrivateKey
+	pub  ed25519.PublicKey
+}
+
+// NewEd25519 creates a new algorithm using EdDSA and SHA-512.
+func NewEd25519(opts ...func(*Ed25519)) *Ed25519 {
+	var ed Ed25519
+	for _, opt := range opts {
+		opt(&ed)
+	}
+	if ed.pub == nil {
+		ed.pub = ed.priv.Public().(ed25519.PublicKey)
+	}
+	return &ed
+}
+
+// Name returns the algorithm's name.
+func (*Ed25519) Name() string {
+	return "Ed25519"
+}
+
+// Sign signs headerPayload using the Ed25519 algorithm.
+func (ed *Ed25519) Sign(headerPayload []byte) ([]byte, error) {
+	if ed.priv == nil {
+		return nil, ErrEd25519PrivKey
+	}
+	return ed25519.Sign(ed.priv, headerPayload), nil
+}
+
+// Size returns the signature byte size.
+func (*Ed25519) Size() int {
+	return ed25519.SignatureSize
+}
+
+// Verify verifies a payload and a signature.
+func (ed *Ed25519) Verify(payload, sig []byte) (err error) {
+	if ed.pub == nil {
+		return ErrEd25519PubKey
+	}
+	if sig, err = internal.DecodeToBytes(sig); err != nil {
+		return err
+	}
+	if !ed25519.Verify(ed.pub, payload, sig) {
+		return ErrEd25519Verification
+	}
+	return nil
+}

internal/ed25519.go

@@ -0,0 +1,17 @@
+// +build go1.13
+
+package internal
+
+import (
+	"crypto/ed25519"
+	"crypto/rand"
+)
+
+// GenerateEd25519Keys generates a pair of keys for testing purposes.
+func GenerateEd25519Keys() (ed25519.PrivateKey, ed25519.PublicKey) {
+	pub, priv, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		panic(err)
+	}
+	return priv, pub
+}