125 lines
3.6 KiB
C#
125 lines
3.6 KiB
C#
using System;
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using System.IO;
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using System.Security.Cryptography;
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using System.Text;
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using Newtonsoft.Json.Linq;
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namespace HuanMeng.DotNetCore.WeChat
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{
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/// <summary>
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///
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/// </summary>
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public class WXBizDataCrypt
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{
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private string appId;
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private string sessionKey;
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/// <summary>
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/// 构造函数
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/// </summary>
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/// <param name="appId">小程序的 appId</param>
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/// <param name="sessionKey">用户在小程序登录后获取的会话密钥</param>
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public WXBizDataCrypt(string appId, string sessionKey)
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{
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this.appId = appId;
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this.sessionKey = sessionKey;
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}
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/// <summary>
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/// 检验数据的真实性，并且获取解密后的明文
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/// </summary>
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/// <param name="encryptedData">加密的用户数据</param>
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/// <param name="iv">与用户数据一同返回的初始向量</param>
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/// <param name="data">解密后的原文</param>
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/// <returns>成功0，失败返回对应的错误码</returns>
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public int DecryptData(string encryptedData, string iv, out string data)
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{
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data = null;
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// 检查 sessionKey 长度
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if (sessionKey.Length != 24)
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{
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return ErrorCode.IllegalAesKey;
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}
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// 检查 iv 长度
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if (iv.Length != 24)
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{
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return ErrorCode.IllegalIv;
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}
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try
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{
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byte[] aesKey = Convert.FromBase64String(sessionKey);
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byte[] aesIV = Convert.FromBase64String(iv);
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byte[] aesCipher = Convert.FromBase64String(encryptedData);
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using (Aes aesAlg = Aes.Create())
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{
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aesAlg.Key = aesKey;
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aesAlg.IV = aesIV;
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aesAlg.Mode = CipherMode.CBC;
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aesAlg.Padding = PaddingMode.PKCS7;
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using (ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV))
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{
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using (MemoryStream msDecrypt = new MemoryStream(aesCipher))
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{
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using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
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{
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using (StreamReader srDecrypt = new StreamReader(csDecrypt))
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{
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// 解密后的明文
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data = srDecrypt.ReadToEnd();
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}
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}
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}
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}
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}
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JObject dataObj = JObject.Parse(data);
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// 检查 appId
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if (dataObj["watermark"]["appid"].ToString() != this.appId)
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{
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return ErrorCode.IllegalBuffer;
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}
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return ErrorCode.OK;
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}
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catch
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{
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return ErrorCode.IllegalBuffer;
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}
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}
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}
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public static class ErrorCode
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{
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public const int OK = 0;
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public const int IllegalAesKey = -41001;
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public const int IllegalIv = -41002;
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public const int IllegalBuffer = -41003;
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}
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public class WXBizDataCryptModel
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{
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public WXBizDataCryptModel() { }
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/// <summary>
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///
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/// </summary>
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public string? EncryptedData;
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/// <summary>
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///
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/// </summary>
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public string? Iv;
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public int UserId { get; set; }
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}
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}
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