feat(wxapi): 新增 AES 解密工具类

src/SKIT.FlurlHttpClient.Wechat.Api/Utilities/AESUtility.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Security;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace SKIT.FlurlHttpClient.Wechat.Api.Utilities
+{
+    public static class AESUtility
+    {
+        /// <summary>
+        /// 解密数据。
+        /// </summary>
+        /// <param name="keyBytes">AES 密钥字节数组。</param>
+        /// <param name="ivBytes">加密使用的初始化向量字节数组。</param>
+        /// <param name="cipherBytes">待解密数据字节数组。</param>
+        /// <returns>解密后的数据字节数组。</returns>
+        public static byte[] Decrypt(byte[] keyBytes, byte[] ivBytes, byte[] cipherBytes)
+        {
+            if (keyBytes == null) throw new ArgumentNullException(nameof(keyBytes));
+            if (ivBytes == null) throw new ArgumentNullException(nameof(ivBytes));
+            if (cipherBytes == null) throw new ArgumentNullException(nameof(cipherBytes));
+
+            using (SymmetricAlgorithm aes = Aes.Create())
+            {
+                aes.Key = keyBytes;
+                aes.IV = ivBytes;
+
+                using (Stream ms = new MemoryStream(cipherBytes))
+                using (Stream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Read))
+                {
+                    byte[] plainBytes = new byte[cipherBytes.Length];
+                    cs.Read(plainBytes, 0, plainBytes.Length);
+                    return plainBytes;
+                }
+            }
+        }
+
+        /// <summary>
+        /// 解密数据。
+        /// </summary>
+        /// <param name="encodingKey">经 Base64 编码后的 AES 密钥。</param>
+        /// <param name="encodingIV">经 Base64 编码后的 AES 初始化向量。</param>
+        /// <param name="encodingCipherText">经 Base64 编码后的待解密数据。</param>
+        /// <returns>解密后的文本数据。</returns>
+        public static string Decrypt(string encodingKey, string encodingIV, string encodingCipherText)
+        {
+            if (encodingKey == null) throw new ArgumentNullException(nameof(encodingKey));
+            if (encodingCipherText == null) throw new ArgumentNullException(nameof(encodingCipherText));
+
+            byte[] plainBytes = Decrypt(
+                keyBytes: Convert.FromBase64String(encodingKey),
+                ivBytes: Convert.FromBase64String(encodingIV),
+                cipherBytes: Convert.FromBase64String(encodingCipherText)
+            );
+            return Encoding.UTF8.GetString(plainBytes);
+        }
+    }
+}