interactions yay!!

interactions/verify.go

@@ -0,0 +1,40 @@
+package interactions
+
+import (
+	"bytes"
+	"crypto/ed25519"
+	"encoding/hex"
+	"errors"
+	"fmt"
+)
+
+var (
+	ErrMissingHeader = errors.New("interactions: missing verification headers")
+	ErrSignatureSize = errors.New("interactions: signature length invalid")
+	ErrNotVerifed    = errors.New("interactions: not verified")
+)
+
+func (i *Interactions) Verify(signature, timestamp string, body []byte) error {
+	if signature == "" || timestamp == "" {
+		return ErrMissingHeader
+	}
+
+	sig, err := hex.DecodeString(signature)
+	if err != nil {
+		return fmt.Errorf("interactions: signature failed to parse: %w", err)
+	}
+
+	if len(sig) != ed25519.SignatureSize || sig[63]&224 != 0 {
+		return ErrSignatureSize
+	}
+
+	buf := bytes.Buffer{}
+	buf.WriteString(timestamp)
+	buf.Write(body)
+
+	if !ed25519.Verify(i.PublicKey, buf.Bytes(), sig) {
+		return ErrNotVerifed
+	}
+
+	return nil
+}