Initial commit: LAN Manager with Go backend and Vue frontend

server/utils/crypto.go

@@ -0,0 +1,78 @@
+package utils
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"io"
+	"log"
+	"os"
+)
+
+var encryptKey []byte
+
+func init() {
+	key := os.Getenv("ENCRYPT_KEY")
+	if key == "" {
+		key = "lan-manager-default-key-change-in-production"
+		log.Println("[WARN] ENCRYPT_KEY not set, using default key. Please set ENCRYPT_KEY in production.")
+	}
+	h := sha256.Sum256([]byte(key))
+	encryptKey = h[:]
+}
+
+// Encrypt 使用 AES-GCM 加密明文，返回 base64 编码的密文
+func Encrypt(plaintext string) (string, error) {
+	if plaintext == "" {
+		return "", nil
+	}
+	block, err := aes.NewCipher(encryptKey)
+	if err != nil {
+		return "", err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return "", err
+	}
+	ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
+	return base64.StdEncoding.EncodeToString(ciphertext), nil
+}
+
+// Decrypt 使用 AES-GCM 解密密文，输入为 base64 编码。
+// 为了兼容升级前的明文密码，如果 base64 解码失败或解密失败，则直接返回原始字符串。
+func Decrypt(ciphertext string) (string, error) {
+	if ciphertext == "" {
+		return "", nil
+	}
+	data, err := base64.StdEncoding.DecodeString(ciphertext)
+	if err != nil {
+		// 兼容旧明文密码
+		return ciphertext, nil
+	}
+	block, err := aes.NewCipher(encryptKey)
+	if err != nil {
+		return "", err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	nonceSize := gcm.NonceSize()
+	if len(data) < nonceSize {
+		// 兼容旧明文密码
+		return ciphertext, nil
+	}
+	nonce, cipherData := data[:nonceSize], data[nonceSize:]
+	plain, err := gcm.Open(nil, nonce, cipherData, nil)
+	if err != nil {
+		// 兼容旧明文密码
+		return ciphertext, nil
+	}
+	return string(plain), nil
+}