Question

c#的AES加密解密问题

初学C#，AES加密已经调试成功，解密时遇到“System.Security.Cryptography.CryptographicException:填充无效，无法被移除。”（图2的红框处）问题，错在哪里？

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Answer 1

不是初学，而是对.net中所有的加解密方式都没有弄清楚。不过别灰心——很多自以为会的人也没有弄清。
首先，.net中类库中支持各类摘要加解密方式。一般情况下我们将安全分为两类，一类是摘要，一类是加解密。加密解又分为对称与非对称加解密。
在.net体系中，不管是摘要还是加解密，为了统一算法方式，一律都是流方式进行的。不管是MD5摘要还是ADE/DES/TDES/RSA等等。一定要记住的第一条，是流方式进行的！
流——这个概念很多人也不清楚，因为stream的范围还是非常的大的，有网络流responseStream等，基本文本流，IO流等等，在加密时我们使用了一个流叫“加解密流”CryptStream，该流用来实现加解密及摘要算法等等。
那么CryptoStream是个什么流呢？它算是转换流，把一种形式转换成另一种形式，比如把密文转换成明文或把明文换成密文。正常的情况下，我们可以用流写流的方式来实现，比如MemoryStream来换流。当然，也可以把byte[]数组直接写到流中。
流这部分说完了，那么，其实我们如何区别CryptoStream是加密还是解密呢，除了说明之外，还是一个方式，就是看流的方式是读还是写！所以当我看到你的解密流中使用的方式竟然是Write,而不是Read，所以你对加解密方式并没有真正理解。
比如，我们可以转换后的流直接进行ReadToLine即可。
老实说，你这种写法有很大问题——有关stream大部分都是非托管，所以一定要记着Dispose，或Close（Close时会自动调用Dispose)。防止出现错误等内存泄露。
有于加解密流，我们经常一句话，加密方式是Write,解密方式是Read!

Answer 2

C# 各种加密方法封装类，软创加密类，内含MD5加密解密、DES法解密加密、RC2加密解密、3DES加密解密，还有AES加解密等，使用时用到哪一种加密方法，可把代码单独摘录出来，本类比较综合，代码中包括注释，完整代码：

view sourceprint?001using System;

002using System.Collections.Generic;

003using System.Text;

004using System.IO;

005using System.Security.Cryptography;

006namespace CLB.Utility.CharTools

007{

008 ///

009 /// 软创加密类

010 ///

011 public static class Cryptography

012 {

013 ///

014 /// MD5 加密,静态方法

015 ///

016 /// 待加密的密文

017 /// returns

018 public static string MD5Encrypt(string EncryptString)

019 {

020 if (string.IsNullOrEmpty(EncryptString)) { throw (new Exception("密文不得为空")); }

021 MD5 m_ClassMD5 = new MD5CryptoServiceProvider();

022 string m_strEncrypt = "";

023 try

024 {

025 m_strEncrypt = BitConverter.ToString(m_ClassMD5.ComputeHash(Encoding.Default.GetBytes(EncryptString))).Replace("-", "");

026 }

027 catch (ArgumentException ex) { throw ex; }

028 catch (CryptographicException ex) { throw ex; }

029 catch (Exception ex) { throw ex; }

030 finally { m_ClassMD5.Clear(); }

031 return m_strEncrypt;

032 }

033 ///

034 /// DES 加密(数据加密标准，速度较快，适用于加密大量数据的场合)

035 ///

036 /// 待加密的密文

037 /// 加密的密钥

038 /// returns

039 public static string DESEncrypt(string EncryptString, string EncryptKey)

040 {

041 if (string.IsNullOrEmpty(EncryptString)) { throw (new Exception("密文不得为空")); }

042 if (string.IsNullOrEmpty(EncryptKey)) { throw (new Exception("密钥不得为空")); }

043 if (EncryptKey.Length != 8) { throw (new Exception("密钥必须为8位")); }

044 byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

045 string m_strEncrypt = "";

046 DESCryptoServiceProvider m_DESProvider = new DESCryptoServiceProvider();

047 try

048 {

049 byte[] m_btEncryptString = Encoding.Default.GetBytes(EncryptString);

050 MemoryStream m_stream = new MemoryStream();

051 CryptoStream m_cstream = new CryptoStream(m_stream, m_DESProvider.CreateEncryptor(Encoding.Default.GetBytes(EncryptKey), m_btIV), CryptoStreamMode.Write);

052 m_cstream.Write(m_btEncryptString, 0, m_btEncryptString.Length);

053 m_cstream.FlushFinalBlock();

054 m_strEncrypt = Convert.ToBase64String(m_stream.ToArray());

055 m_stream.Close(); m_stream.Dispose();

056 m_cstream.Close(); m_cstream.Dispose();

057 }

058 catch (IOException ex) { throw ex; }

059 catch (CryptographicException ex) { throw ex; }

060 catch (ArgumentException ex) { throw ex; }

061 catch (Exception ex) { throw ex; }

062 finally { m_DESProvider.Clear(); }

063 return m_strEncrypt;

064 }

065 ///

066 /// DES 解密(数据加密标准，速度较快，适用于加密大量数据的场合)

067 ///

068 /// 待解密的密文

069 /// 解密的密钥

070 /// returns

071 public static string DESDecrypt(string DecryptString, string DecryptKey)

072 {

073 if (string.IsNullOrEmpty(DecryptString)) { throw (new Exception("密文不得为空")); }

074 if (string.IsNullOrEmpty(DecryptKey)) { throw (new Exception("密钥不得为空")); }

075 if (DecryptKey.Length != 8) { throw (new Exception("密钥必须为8位")); }

076 byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

077 string m_strDecrypt = "";

078 DESCryptoServiceProvider m_DESProvider = new DESCryptoServiceProvider();

079 try

080 {

081 byte[] m_btDecryptString = Convert.FromBase64String(DecryptString);

082 MemoryStream m_stream = new MemoryStream();

083 CryptoStream m_cstream = new CryptoStream(m_stream, m_DESProvider.CreateDecryptor(Encoding.Default.GetBytes(DecryptKey), m_btIV), CryptoStreamMode.Write);

084 m_cstream.Write(m_btDecryptString, 0, m_btDecryptString.Length);

085 m_cstream.FlushFinalBlock();

086 m_strDecrypt = Encoding.Default.GetString(m_stream.ToArray());

087 m_stream.Close(); m_stream.Dispose();

088 m_cstream.Close(); m_cstream.Dispose();

089 }

090 catch (IOException ex) { throw ex; }

091 catch (CryptographicException ex) { throw ex; }

092 catch (ArgumentException ex) { throw ex; }

093 catch (Exception ex) { throw ex; }

094 finally { m_DESProvider.Clear(); }

095 return m_strDecrypt;

096 }

097 ///

098 /// RC2 加密(用变长密钥对大量数据进行加密)

099 ///

100 /// 待加密密文

101 /// 加密密钥

102 /// returns

103 public static string RC2Encrypt(string EncryptString, string EncryptKey)

104 {

105 if (string.IsNullOrEmpty(EncryptString)) { throw (new Exception("密文不得为空")); }

106 if (string.IsNullOrEmpty(EncryptKey)) { throw (new Exception("密钥不得为空")); }

107 if (EncryptKey.Length < 5 || EncryptKey.Length > 16) { throw (new Exception("密钥必须为5-16位")); }

108 string m_strEncrypt = "";

109 byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

110 RC2CryptoServiceProvider m_RC2Provider = new RC2CryptoServiceProvider();

111 try

112 {

113 byte[] m_btEncryptString = Encoding.Default.GetBytes(EncryptString);

114 MemoryStream m_stream = new MemoryStream();

115 CryptoStream m_cstream = new CryptoStream(m_stream, m_RC2Provider.CreateEncryptor(Encoding.Default.GetBytes(EncryptKey), m_btIV), CryptoStreamMode.Write);

116 m_cstream.Write(m_btEncryptString, 0, m_btEncryptString.Length);

117 m_cstream.FlushFinalBlock();

118 m_strEncrypt = Convert.ToBase64String(m_stream.ToArray());

119 m_stream.Close(); m_stream.Dispose();

120 m_cstream.Close(); m_cstream.Dispose();

121 }

122 catch (IOException ex) { throw ex; }

123 catch (CryptographicException ex) { throw ex; }

124 catch (ArgumentException ex) { throw ex; }

125 catch (Exception ex) { throw ex; }

126 finally { m_RC2Provider.Clear(); }

127 return m_strEncrypt;

128 }

129 ///

130 /// RC2 解密(用变长密钥对大量数据进行加密)

131 ///

132 /// 待解密密文

133 /// 解密密钥

134 /// returns

135 public static string RC2Decrypt(string DecryptString, string DecryptKey)

136 {

137 if (string.IsNullOrEmpty(DecryptString)) { throw (new Exception("密文不得为空")); }

138 if (string.IsNullOrEmpty(DecryptKey)) { throw (new Exception("密钥不得为空")); }

139 if (DecryptKey.Length < 5 || DecryptKey.Length > 16) { throw (new Exception("密钥必须为5-16位")); }

140 byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

141 string m_strDecrypt = "";

142 RC2CryptoServiceProvider m_RC2Provider = new RC2CryptoServiceProvider();

143 try

144 {

145 byte[] m_btDecryptString = Convert.FromBase64String(DecryptString);

146 MemoryStream m_stream = new MemoryStream();

147 CryptoStream m_cstream = new CryptoStream(m_stream, m_RC2Provider.CreateDecryptor(Encoding.Default.GetBytes(DecryptKey), m_btIV), CryptoStreamMode.Write);

148 m_cstream.Write(m_btDecryptString, 0, m_btDecryptString.Length);

149 m_cstream.FlushFinalBlock();

150 m_strDecrypt = Encoding.Default.GetString(m_stream.ToArray());

151 m_stream.Close(); m_stream.Dispose();

152 m_cstream.Close(); m_cstream.Dispose();

153 }

154 catch (IOException ex) { throw ex; }

155 catch (CryptographicException ex) { throw ex; }

156 catch (ArgumentException ex) { throw ex; }

157 catch (Exception ex) { throw ex; }

158 finally { m_RC2Provider.Clear(); }

159 return m_strDecrypt;

160 }

161 ///

162 /// 3DES 加密(基于DES，对一块数据用三个不同的密钥进行三次加密，强度更高)

163 ///

164 /// 待加密密文

165 /// 密钥一

166 /// 密钥二

167 /// 密钥三

168 /// returns

169 public static string DES3Encrypt(string EncryptString, string EncryptKey1, string EncryptKey2, stringEncryptKey3)

170 {

171 string m_strEncrypt = "";

172 try

173 {

174 m_strEncrypt = DESEncrypt(EncryptString, EncryptKey3);

175 m_strEncrypt = DESEncrypt(m_strEncrypt, EncryptKey2);

176 m_strEncrypt = DESEncrypt(m_strEncrypt, EncryptKey1);

177 }

178 catch (Exception ex) { throw ex; }

179 return m_strEncrypt;

180 }

181 ///

182 /// 3DES 解密(基于DES，对一块数据用三个不同的密钥进行三次加密，强度更高)

183 ///

184 /// 待解密密文

185 /// 密钥一

186 /// 密钥二

187 /// 密钥三

188 /// returns

189 public static string DES3Decrypt(string DecryptString, string DecryptKey1, string DecryptKey2, stringDecryptKey3)

190 {

191 string m_strDecrypt = "";

192 try

193 {

194 m_strDecrypt = DESDecrypt(DecryptString, DecryptKey1);

195 m_strDecrypt = DESDecrypt(m_strDecrypt, DecryptKey2);

196 m_strDecrypt = DESDecrypt(m_strDecrypt, DecryptKey3);

197 }

198 catch (Exception ex) { throw ex; }

199 return m_strDecrypt;

200 }

201 ///

202 /// AES 加密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)

203 ///

204 /// 待加密密文

205 /// 加密密钥

206 ///

207 public static string AESEncrypt(string EncryptString, string EncryptKey)

208 {

209 if (string.IsNullOrEmpty(EncryptString)) { throw (new Exception("密文不得为空")); }

210 if (string.IsNullOrEmpty(EncryptKey)) { throw (new Exception("密钥不得为空")); }

211 string m_strEncrypt = "";

212 byte[] m_btIV = Convert.FromBase64String("Rkb4jvUy/ye7Cd7k89QQgQ==");

213 Rijndael m_AESProvider = Rijndael.Create();

214 try

215 {

216 byte[] m_btEncryptString = Encoding.Default.GetBytes(EncryptString);

217 MemoryStream m_stream = new MemoryStream();

218 CryptoStream m_csstream = new CryptoStream(m_stream, m_AESProvider.CreateEncryptor(Encoding.Default.GetBytes(EncryptKey), m_btIV), CryptoStreamMode.Write);

219 m_csstream.Write(m_btEncryptString, 0, m_btEncryptString.Length); m_csstream.FlushFinalBlock();

220 m_strEncrypt = Convert.ToBase64String(m_stream.ToArray());

221 m_stream.Close(); m_stream.Dispose();

222 m_csstream.Close(); m_csstream.Dispose();

223 }

224 catch (IOException ex) { throw ex; }

225 catch (CryptographicException ex) { throw ex; }

226 catch (ArgumentException ex) { throw ex; }

227 catch (Exception ex) { throw ex; }

228 finally { m_AESProvider.Clear(); }

229 return m_strEncrypt;

230 }

231 ///

232 /// AES 解密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)

233 ///

234 /// 待解密密文

235 /// 解密密钥

236 ///

237 public static string AESDecrypt(string DecryptString, string DecryptKey)

238 {

239 if (string.IsNullOrEmpty(DecryptString)) { throw (new Exception("密文不得为空")); }

240 if (string.IsNullOrEmpty(DecryptKey)) { throw (new Exception("密钥不得为空")); }

241 string m_strDecrypt = "";

242 byte[] m_btIV = Convert.FromBase64String("Rkb4jvUy/ye7Cd7k89QQgQ==");

243 Rijndael m_AESProvider = Rijndael.Create();

244 try

245 {

246 byte[] m_btDecryptString = Convert.FromBase64String(DecryptString);

247 MemoryStream m_stream = new MemoryStream();

248 CryptoStream m_csstream = new CryptoStream(m_stream, m_AESProvider.CreateDecryptor(Encoding.Default.GetBytes(DecryptKey), m_btIV), CryptoStreamMode.Write);

249 m_csstream.Write(m_btDecryptString, 0, m_btDecryptString.Length); m_csstream.FlushFinalBlock();

250 m_strDecrypt = Encoding.Default.GetString(m_stream.ToArray());

251 m_stream.Close(); m_stream.Dispose();

252 m_csstream.Close(); m_csstream.Dispose();

253 }

254 catch (IOException ex) { throw ex; }

255 catch (CryptographicException ex) { throw ex; }

256 catch (ArgumentException ex) { throw ex; }

257 catch (Exception ex) { throw ex; }

258 finally { m_AESProvider.Clear(); }

259 return m_strDecrypt;

260 }

261 }

262}