wacky encryption

client/crypto.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"crypto/rand"
+	"fmt"
+
+	"golang.org/x/crypto/chacha20poly1305"
+)
+
+func EncryptSym(key []byte, plaintext []byte) ([]byte, error) {
+	aead, err := chacha20poly1305.NewX(key)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, chacha20poly1305.NonceSizeX)
+	if _, err := rand.Read(nonce); err != nil {
+		return nil, err
+	}
+
+	return aead.Seal(nonce, nonce, plaintext, nil), nil
+}
+
+func DecryptSym(key []byte, ciphertext []byte) ([]byte, error) {
+	aead, err := chacha20poly1305.NewX(key)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(ciphertext) < aead.NonceSize() {
+		return nil, fmt.Errorf("ciphertext too short")
+	}
+	nonce, ciphertext := ciphertext[:aead.NonceSize()], ciphertext[aead.NonceSize():]
+
+	return aead.Open(nil, nonce, ciphertext, nil)
+}