refactor!: working WD-4 user discovery

pkg/lysand/crypto/keys.go

@@ -0,0 +1,23 @@
+package versiacrypto
+
+import (
+	"crypto/ed25519"
+	"fmt"
+)
+
+type UnknownPublicKeyTypeError struct {
+	Got string
+}
+
+func (i UnknownPublicKeyTypeError) Error() string {
+	return fmt.Sprintf("unknown public key type: \"%s\"", i.Got)
+}
+
+func ToTypedKey(algorithm string, raw []byte) (any, error) {
+	switch algorithm {
+	case "ed25519":
+		return ed25519.PublicKey(raw), nil
+	default:
+		return nil, UnknownPublicKeyTypeError{algorithm}
+	}
+}

pkg/lysand/crypto/sha256.go

@@ -0,0 +1,9 @@
+package versiacrypto
+
+import "crypto/sha256"
+
+func SHA256(data []byte) []byte {
+	h := sha256.New()
+	h.Write(data)
+	return h.Sum(nil)
+}

pkg/lysand/crypto/verify.go

@@ -0,0 +1,29 @@
+package versiacrypto
+
+import (
+	"crypto"
+	"crypto/ed25519"
+	"fmt"
+	"reflect"
+)
+
+type InvalidPublicKeyTypeError struct {
+	Got reflect.Type
+}
+
+func (i InvalidPublicKeyTypeError) Error() string {
+	return fmt.Sprintf("failed to convert public key of type \"%s\"", i.Got.String())
+}
+
+type Verify = func(data, signature []byte) bool
+
+func NewVerify(pubKey crypto.PublicKey) (Verify, error) {
+	switch pk := pubKey.(type) {
+	case ed25519.PublicKey:
+		return func(data, signature []byte) bool {
+			return ed25519.Verify(pk, data, signature)
+		}, nil
+	default:
+		return nil, InvalidPublicKeyTypeError{reflect.TypeOf(pk)}
+	}
+}