refactor(backend): extract to pkg/cap

pkg/util/crypto.go

@@ -0,0 +1,160 @@
+// Copyright 2025 linux.do
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package util provides generic utility functions.
+package util
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/ed25519"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+)
+
+const (
+	aesKeyLength = 32
+
+	errInvalidSignKey         = "invalid sign key: %w"
+	errSignKeyLengthInvalid   = "sign key must be 32 bytes (64 hex characters)"
+	errCreateCipherFailed     = "failed to create cipher: %w"
+	errCreateGCMFailed        = "failed to create GCM: %w"
+	errGenerateNonceFailed    = "failed to generate nonce: %w"
+	errDecodeCiphertextFailed = "failed to decode ciphertext: %w"
+	errCiphertextTooShort     = "ciphertext too short"
+	errDecryptFailed          = "failed to decrypt: %w"
+)
+
+// Encrypt 使用 SignKey 加密字符串数据
+// signKey: 64 字符 hex 编码的密钥（对应 32 字节，用于 AES-256）
+// plaintext: 要加密的明文字符串
+// return: base64 编码的密文
+func Encrypt(signKey string, plaintext string) (string, error) {
+	return encryptBytes(signKey, []byte(plaintext))
+}
+
+// Decrypt 使用 SignKey 解密字符串数据
+// signKey: 64 字符 hex 编码的密钥（对应 32 字节，用于 AES-256）
+// ciphertext: base64 编码的密文
+// return: 解密后的明文字符串
+func Decrypt(signKey string, ciphertext string) (string, error) {
+	plaintext, err := decryptBytes(signKey, ciphertext)
+	if err != nil {
+		return "", err
+	}
+	return string(plaintext), nil
+}
+
+// encryptBytes 加密函数，处理字节数据
+func encryptBytes(signKey string, plaintext []byte) (string, error) {
+	// 将 hex 编码的密钥转换为字节
+	key, err := hex.DecodeString(signKey)
+	if err != nil {
+		return "", fmt.Errorf(errInvalidSignKey, err)
+	}
+	if len(key) != aesKeyLength {
+		return "", errors.New(errSignKeyLengthInvalid)
+	}
+
+	// 创建 AES cipher
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", fmt.Errorf(errCreateCipherFailed, err)
+	}
+
+	// 使用 GCM 模式（Galois/Counter Mode）
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf(errCreateGCMFailed, err)
+	}
+
+	// 生成随机 nonce
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return "", fmt.Errorf(errGenerateNonceFailed, err)
+	}
+
+	// 加密数据
+	ciphertext := gcm.Seal(nonce, nonce, plaintext, nil)
+
+	// 返回 base64 编码的密文
+	return Base64Encode(ciphertext), nil
+}
+
+// decryptBytes 解密函数，处理字节数据
+func decryptBytes(signKey string, ciphertext string) ([]byte, error) {
+	// 将 hex 编码的密钥转换为字节
+	key, err := hex.DecodeString(signKey)
+	if err != nil {
+		return nil, fmt.Errorf(errInvalidSignKey, err)
+	}
+	if len(key) != aesKeyLength {
+		return nil, errors.New(errSignKeyLengthInvalid)
+	}
+
+	// 解码 base64 密文
+	data, err := Base64Decode(ciphertext)
+	if err != nil {
+		return nil, fmt.Errorf(errDecodeCiphertextFailed, err)
+	}
+
+	// 创建 AES cipher
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, fmt.Errorf(errCreateCipherFailed, err)
+	}
+
+	// 使用 GCM 模式
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, fmt.Errorf(errCreateGCMFailed, err)
+	}
+
+	// 提取 nonce
+	nonceSize := gcm.NonceSize()
+	if len(data) < nonceSize {
+		return nil, errors.New(errCiphertextTooShort)
+	}
+
+	nonce, ciphertextBytes := data[:nonceSize], data[nonceSize:]
+
+	// 解密数据
+	plaintext, err := gcm.Open(nil, nonce, ciphertextBytes, nil)
+	if err != nil {
+		return nil, fmt.Errorf(errDecryptFailed, err)
+	}
+
+	return plaintext, nil
+}
+
+// Base64Encode Base64编码
+func Base64Encode(data []byte) string {
+	return base64.StdEncoding.EncodeToString(data)
+}
+
+// Base64Decode Base64解码
+func Base64Decode(encoded string) ([]byte, error) {
+	return base64.StdEncoding.DecodeString(encoded)
+}
+
+// Ed25519Verify 验证 Ed25519 签名
+// publicKey: 32 字节的公钥（已解码的二进制格式）
+// message: 待验证的原始消息
+// signature: 64 字节的签名（已解码的二进制格式）
+// return: 签名是否有效
+func Ed25519Verify(publicKey, message, signature []byte) bool {
+	if len(publicKey) != ed25519.PublicKeySize {
+		return false
+	}
+
+	if len(signature) != ed25519.SignatureSize {
+		return false
+	}
+
+	return ed25519.Verify(publicKey, message, signature)
+}