Make sizes public and add DecodePublicKey function

protocol/meshcore/crypto/ed25519.go

@@ -13,23 +13,24 @@ import (
 	"filippo.io/edwards25519"
 )
 
+// Byte sizes of key material.
 const (
-	seedSize       = 32
-	publicKeySize  = 32
-	privateKeySize = seedSize + publicKeySize
+	SeedSize       = 32
+	PublicKeySize  = 32
+	PrivateKeySize = SeedSize + PublicKeySize
 	signatureSize  = 64
 	sha512Size     = 64
 )
 
 type PrivateKey struct {
-	seed   [seedSize]byte
-	pub    [publicKeySize]byte
+	seed   [SeedSize]byte
+	pub    [PublicKeySize]byte
 	s      edwards25519.Scalar
 	prefix [sha512Size / 2]byte
 }
 
 func (priv *PrivateKey) Bytes() []byte {
-	k := make([]byte, 0, privateKeySize)
+	k := make([]byte, 0, PrivateKeySize)
 	k = append(k, priv.seed[:]...)
 	k = append(k, priv.pub[:]...)
 	return k
@@ -116,7 +117,7 @@ func NewPrivateKeyFromSeed(seed []byte) (*PrivateKey, error) {
 }
 
 func newPrivateKeyFromSeed(priv *PrivateKey, seed []byte) (*PrivateKey, error) {
-	if l := len(seed); l != seedSize {
+	if l := len(seed); l != SeedSize {
 		return nil, errors.New("ed25519: bad seed length: " + strconv.Itoa(l))
 	}
 	copy(priv.seed[:], seed)
@@ -124,6 +125,47 @@ func newPrivateKeyFromSeed(priv *PrivateKey, seed []byte) (*PrivateKey, error) {
 	return priv, nil
 }
 
+func DecodePrivateKey(s string) (*PrivateKey, error) {
+	var (
+		b   []byte
+		err error
+	)
+	switch len(s) {
+	case hex.EncodedLen(SeedSize):
+		if b, err = hex.DecodeString(s); err != nil {
+			return nil, err
+		}
+		return NewPrivateKeyFromSeed(b)
+	case hex.EncodedLen(PrivateKeySize):
+		if b, err = hex.DecodeString(s); err != nil {
+			return nil, err
+		}
+		return NewPrivateKey(b)
+	case base64.RawStdEncoding.EncodedLen(SeedSize):
+		if b, err = base64.RawStdEncoding.DecodeString(s); err != nil {
+			return nil, err
+		}
+		return NewPrivateKeyFromSeed(b)
+	case base64.RawStdEncoding.EncodedLen(PrivateKeySize):
+		if b, err = base64.RawStdEncoding.DecodeString(s); err != nil {
+			return nil, err
+		}
+		return NewPrivateKey(b)
+	case base64.StdEncoding.EncodedLen(SeedSize):
+		if b, err = base64.StdEncoding.DecodeString(s); err != nil {
+			return nil, err
+		}
+		return NewPrivateKeyFromSeed(b)
+	case base64.StdEncoding.EncodedLen(PrivateKeySize):
+		if b, err = base64.StdEncoding.DecodeString(s); err != nil {
+			return nil, err
+		}
+		return NewPrivateKey(b)
+	default:
+		return nil, errors.New("ed25519: unknown private key encoding")
+	}
+}
+
 func precomputePrivateKey(priv *PrivateKey) {
 	hs := sha512.New()
 	hs.Write(priv.seed[:])
@@ -145,7 +187,7 @@ func NewPrivateKey(priv []byte) (*PrivateKey, error) {
 }
 
 func newPrivateKey(priv *PrivateKey, privBytes []byte) (*PrivateKey, error) {
-	if l := len(privBytes); l != privateKeySize {
+	if l := len(privBytes); l != PrivateKeySize {
 		return nil, errors.New("ed25519: bad private key length: " + strconv.Itoa(l))
 	}
 
@@ -196,7 +238,7 @@ func NewPublicKey(pub []byte) (*PublicKey, error) {
 }
 
 func newPublicKey(pub *PublicKey, pubBytes []byte) (*PublicKey, error) {
-	if l := len(pubBytes); l != publicKeySize {
+	if l := len(pubBytes); l != PublicKeySize {
 		return nil, errors.New("ed25519: bad public key length: " + strconv.Itoa(l))
 	}
 	// SetBytes checks that the point is on the curve.