From 251a66f826ad9e222da59587aefac95d34a64d67 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Fri, 18 Apr 2025 17:15:43 -0400
Subject: implement saltpack.BoxSecretKey

---
 key/box.go | 43 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 36 insertions(+), 7 deletions(-)

(limited to 'key')

diff --git a/key/box.go b/key/box.go
index a93c11a..f32692a 100644
--- a/key/box.go
+++ b/key/box.go
@@ -14,23 +14,31 @@ type BoxPublicKey [32]byte
 // BoxPrivateKey is a private NaCl box key.
 type BoxPrivateKey [32]byte
 
+type BoxKeypair struct {
+	Public  BoxPublicKey
+	Private BoxPrivateKey
+}
+
 // LoadBoxKeypair reads the public and private NaCl box keys from disc,
 // or generates a new keypair if it does not already exist.
 // These keys can be used for NaCl box (encryption/decryption) operations.
-func LoadBoxKeypair() (pub BoxPublicKey, priv BoxPrivateKey, err error) {
-	err = generateBoxKeypairIfNotExist()
+func LoadBoxKeypair() (BoxKeypair, error) {
+	err := generateBoxKeypairIfNotExist()
 	if err != nil {
-		return
+		return BoxKeypair{}, err
 	}
 
-	pub, err = loadBoxKey(boxPubKeyFile)
+	pub, err := loadBoxKey(boxPubKeyFile)
 	if err != nil {
-		return
+		return BoxKeypair{}, err
 	}
 
-	priv, err = loadBoxKey(boxPrivKeyFile)
+	priv, err := loadBoxKey(boxPrivKeyFile)
+	if err != nil {
+		return BoxKeypair{}, err
+	}
 
-	return
+	return BoxKeypair{pub, priv}, nil
 }
 
 // LoadBoxPublicKey reads the public NaCl box key from disc,
@@ -86,3 +94,24 @@ func (key BoxPublicKey) ToRawBoxKeyPointer() *saltpack.RawBoxKey {
 func (key BoxPublicKey) HideIdentity() bool {
 	return false
 }
+
+func (pair BoxKeypair) Box(receiver saltpack.BoxPublicKey, nonce saltpack.Nonce, msg []byte) []byte {
+	return pair.secretKey().Box(receiver, nonce, msg)
+}
+
+func (pair BoxKeypair) Unbox(sender saltpack.BoxPublicKey, nonce saltpack.Nonce, msg []byte) ([]byte, error) {
+	return pair.secretKey().Unbox(sender, nonce, msg)
+}
+
+func (pair BoxKeypair) GetPublicKey() saltpack.BoxPublicKey {
+	return pair.Public
+}
+
+func (pair BoxKeypair) Precompute(peer saltpack.BoxPublicKey) saltpack.BoxPrecomputedSharedKey {
+	return pair.secretKey().Precompute(peer)
+}
+
+func (pair BoxKeypair) secretKey() saltpack.BoxSecretKey {
+	pub, sec := [32]byte(pair.Public), [32]byte(pair.Private)
+	return basic.NewSecretKey(&pub, &sec)
+}
-- 
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