add encryption and get page

internal/crypto/decrypt_on.go

@@ -0,0 +1,35 @@
+//go:build encon
+// +build encon
+
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/hex"
+	"fmt"
+)
+
+func Decrypt(hexedcipher string) (plaintext string, err error) {
+	aes, err := aes.NewCipher(someDumbKey)
+	if err != nil {
+		return "", fmt.Errorf("making new cipher: %w", err)
+	}
+	gcm, err := cipher.NewGCM(aes)
+	if err != nil {
+		return "", fmt.Errorf("making new gcm: %w", err)
+	}
+
+	nonceSize := gcm.NonceSize()
+	valueDecoded, err := hex.DecodeString(hexedcipher)
+	if err != nil {
+		return "", fmt.Errorf("decoding hexed value: %w", err)
+	}
+	nonce, cipherText := valueDecoded[:nonceSize], valueDecoded[nonceSize:]
+	plaintextRaw, err := gcm.Open(nil, []byte(nonce), []byte(cipherText), nil)
+	if err != nil {
+		return "", fmt.Errorf("opening: %w", err)
+	}
+
+	return string(plaintextRaw), nil
+}