draft

backend/pkg/crypto/aes.go

@@ -0,0 +1,72 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"io"
+)
+
+// Encrypt 使用 AES-256-GCM 加密明文，返回 base64 编码的密文
+func Encrypt(plaintext, key string) (string, error) {
+	keyBytes := []byte(key)
+	if len(keyBytes) != 32 {
+		return "", errors.New("encrypt key must be 32 bytes")
+	}
+
+	block, err := aes.NewCipher(keyBytes)
+	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-256-GCM 解密
+func Decrypt(ciphertextB64, key string) (string, error) {
+	keyBytes := []byte(key)
+	if len(keyBytes) != 32 {
+		return "", errors.New("decrypt key must be 32 bytes")
+	}
+
+	ciphertext, err := base64.StdEncoding.DecodeString(ciphertextB64)
+	if err != nil {
+		return "", err
+	}
+
+	block, err := aes.NewCipher(keyBytes)
+	if err != nil {
+		return "", err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+
+	nonceSize := gcm.NonceSize()
+	if len(ciphertext) < nonceSize {
+		return "", errors.New("ciphertext too short")
+	}
+
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return "", err
+	}
+
+	return string(plaintext), nil
+}