102 lines
2.8 KiB
Swift
102 lines
2.8 KiB
Swift
//// CryptorService.swift
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// QJDrama
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//
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// Created by Yao on 2025/4/16
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//
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//
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import Foundation
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class CryptorService {
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// 定义常量
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static let EN_STR_TAG: String = "$" // 替换为实际的加密标记
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// 解密字符串
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static func decrypt(data: String) -> String {
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guard data.hasPrefix(EN_STR_TAG) else {
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// fatalError("Invalid encoded string")
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return data
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}
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let decryptedData = deStrBytes(data: data)
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return String(data: decryptedData, encoding: .utf8) ?? ""
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}
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// 从十六进制字符串解密字节
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static func deStrBytes(data: String) -> Data {
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let hexData = String(data.dropFirst())
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var bytes = Data()
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var index = hexData.startIndex
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while index < hexData.endIndex {
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let nextIndex = hexData.index(index, offsetBy: 2, limitedBy: hexData.endIndex) ?? hexData.endIndex
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let byteString = String(hexData[index..<nextIndex])
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if let byte = UInt8(byteString, radix: 16) {
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bytes.append(byte)
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}
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index = nextIndex
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}
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return de(data: bytes)
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}
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// 解密数据
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static func de(data: Data) -> Data {
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guard !data.isEmpty else {
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return data
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}
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let saltLen = Int(data[data.startIndex])
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guard data.count >= 1 + saltLen else {
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return data
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}
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let salt = data.subdata(in: 1..<1+saltLen)
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let encryptedData = data.subdata(in: 1+saltLen..<data.count)
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return deWithSalt(data: encryptedData, salt: salt)
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}
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// 使用盐值解密数据
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static func deWithSalt(data: Data, salt: Data) -> Data {
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let decryptedData = cxEd(data: data)
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return removeSalt(data: decryptedData, salt: salt)
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}
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// 加密/解密数据（按位取反）
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static func cxEd(data: Data) -> Data {
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return Data(data.map { $0 ^ 0xFF })
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}
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// 从数据中移除盐值
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static func removeSalt(data: Data, salt: Data) -> Data {
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guard !salt.isEmpty else {
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return data
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}
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var result = Data()
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let saltBytes = [UInt8](salt)
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let saltCount = saltBytes.count
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for (index, byte) in data.enumerated() {
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let saltByte = saltBytes[index % saltCount]
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let decryptedByte = calRemoveSalt(v: byte, s: saltByte)
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result.append(decryptedByte)
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}
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return result
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}
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// 计算移除盐值后的字节
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static func calRemoveSalt(v: UInt8, s: UInt8) -> UInt8 {
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if v >= s {
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return v - s
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} else {
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return UInt8(0xFF) - (s - v) + 1
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}
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}
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}
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