加密和解密字符串 [英] Encrypt and decrypt a string
本文介绍了加密和解密字符串的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
解决方案
EDIT 2013-Oct ：虽然我已经编辑了这个答案，以解决缺点，但请参阅 jbtule的答案，以获得更强大的，通知解决方案。
https://stackoverflow.com/a/10366194 / 188474
原始答案
这是一个工作示例衍生自RijndaelManaged类文档和 MCTS培训套件。
EDIT 2012年4月：此答案经过编辑，可以预先为每个jbtule的建议提供IV，如下所示：
http://msdn.microsoft.com/en-us/library/system.security.cryptography.aesmanaged%28v=vs.95%29.aspx
祝你好运！
public class Crypto
{
//虽然应用程序特定的盐不是
//基于密码的加密的最佳做法，但只要
//真的不常见，这可能是足够安全的。另外太多的工作要改变这个答案。
private static byte [] _salt = __To_Do __（在此添加应用程序特定的盐）;
///< summary>
///使用AES加密给定的字符串。该字符串可以使用
/// DecryptStringAES（）进行解密。 sharedSecret参数必须匹配。
///< / summary>
///< param name =plainText>要加密的文本。< / param>
///< param name =sharedSecret>用于生成加密密钥的密码< / param>
public static string EncryptStringAES（string plainText，string sharedSecret）
{
if（string.IsNullOrEmpty（plainText））
throw new ArgumentNullException（plainText）;
if（string.IsNullOrEmpty（sharedSecret））
throw new ArgumentNullException（sharedSecret）;
string outStr = null; //加密字符串返回
RijndaelManaged aesAlg = null; // Rijndael用于加密数据的管理对象。
尝试
{
//从共享密钥和盐生成密钥
Rfc2898DeriveBytes key = new Rfc2898DeriveBytes（sharedSecret，_salt）;
//创建一个RijndaelManaged对象
aesAlg = new RijndaelManaged（）;
aesAlg.Key = key.GetBytes（aesAlg.KeySize / 8）;
//创建解密器来执行流转换。
ICryptoTransform encryptor = aesAlg.CreateEncryptor（aesAlg.Key，aesAlg.IV）;
//创建用于加密的流。
using（MemoryStream msEncrypt = new MemoryStream（））
{
//前缀IV
msEncrypt.Write（BitConverter.GetBytes（aesAlg.IV.Length），0，sizeof （INT））;
msEncrypt.Write（aesAlg.IV，0，aesAlg.IV.Length）;
using（CryptoStream csEncrypt = new CryptoStream（msEncrypt，encryptor，CryptoStreamMode.Write））
{
using（StreamWriter swEncrypt = new StreamWriter（csEncrypt））
{
//将所有数据写入流。
swEncrypt.Write（plainText）;
}
}
outStr = Convert.ToBase64String（msEncrypt.ToArray（））;
}
}
finally
{
//清除RijndaelManaged对象。
if（aesAlg！= null）
aesAlg.Clear（）;
}
//从内存流返回加密的字节。
return outStr;
}
///< summary>
///解密给定的字符串。假设字符串使用
/// EncryptStringAES（）加密，使用相同的sharedSecret。
///< / summary>
///< param name =cipherText>要解密的文本。< / param>
///< param name =sharedSecret>用于生成解密密钥的密码< / param>
public static string DecryptStringAES（string cipherText，string sharedSecret）
{
if（string.IsNullOrEmpty（cipherText））
throw new ArgumentNullException（cipherText）;
if（string.IsNullOrEmpty（sharedSecret））
throw new ArgumentNullException（sharedSecret）;
//声明RijndaelManaged对象
//用于解密数据。
RijndaelManaged aesAlg = null;
//声明用于保存
//解密文本的字符串。
string plaintext = null;
尝试
{
//从共享密钥和盐生成密钥
Rfc2898DeriveBytes key = new Rfc2898DeriveBytes（sharedSecret，_salt）;
//创建用于解密的流。
byte [] bytes = Convert.FromBase64String（cipherText）;
使用（MemoryStream msDecrypt = new MemoryStream（bytes））
{
//使用指定的键创建一个RijndaelManaged对象
//和IV。
aesAlg = new RijndaelManaged（）;
aesAlg.Key = key.GetBytes（aesAlg.KeySize / 8）;
//从加密流获取初始化向量
aesAlg.IV = ReadByteArray（msDecrypt）;
//创建一个解密器来执行流转换。
ICryptoTransform decryptor = aesAlg.CreateDecryptor（aesAlg.Key，aesAlg.IV）;
using（CryptoStream csDecrypt = new CryptoStream（msDecrypt，decryptor，CryptoStreamMode.Read））
{
using（StreamReader srDecrypt = new StreamReader（csDecrypt））
/ /从解密流
//读取解密的字节，并将它们放在字符串中。
plaintext = srDecrypt.ReadToEnd（）;
}
}
}
finally
{
//清除RijndaelManaged对象。
if（aesAlg！= null）
aesAlg.Clear（）;
}
返回明文;
}
private static byte [] ReadByteArray（Stream s）
{
byte [] rawLength = new byte [sizeof（int）];
如果（s.Read（rawLength，0，rawLength.Length）！= rawLength.Length）
{
抛出新的SystemException（Stream不包含正确格式的字节数组）;
}
byte [] buffer = new byte [BitConverter.ToInt32（rawLength，0）];
if（s.Read（buffer，0，buffer.Length）！= buffer.Length）
{
throw new SystemException（没有正确读取字节数组）;
}
返回缓冲区;
}
}
Can someone give me the code to encrypt and decrypt a string in C#?
解决方案
EDIT 2013-Oct: Although I've edited this answer over time to address shortcomings, please see jbtule's answer for a more robust, informed solution.
https://stackoverflow.com/a/10366194/188474
Original Answer:
Here's a working example derived from the "RijndaelManaged Class" documentation and the MCTS Training Kit.
EDIT 2012-April: This answer was edited to pre-pend the IV per jbtule's suggestion and as illustrated here:
http://msdn.microsoft.com/en-us/library/system.security.cryptography.aesmanaged%28v=vs.95%29.aspx
Good luck!
public class Crypto
{
//While an app specific salt is not the best practice for
//password based encryption, it's probably safe enough as long as
//it is truly uncommon. Also too much work to alter this answer otherwise.
private static byte[] _salt = __To_Do__("Add a app specific salt here");
/// <summary>
/// Encrypt the given string using AES. The string can be decrypted using
/// DecryptStringAES(). The sharedSecret parameters must match.
/// </summary>
/// <param name="plainText">The text to encrypt.</param>
/// <param name="sharedSecret">A password used to generate a key for encryption.</param>
public static string EncryptStringAES(string plainText, string sharedSecret)
{
if (string.IsNullOrEmpty(plainText))
throw new ArgumentNullException("plainText");
if (string.IsNullOrEmpty(sharedSecret))
throw new ArgumentNullException("sharedSecret");
string outStr = null; // Encrypted string to return
RijndaelManaged aesAlg = null; // RijndaelManaged object used to encrypt the data.
try
{
// generate the key from the shared secret and the salt
Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);
// Create a RijndaelManaged object
aesAlg = new RijndaelManaged();
aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
// Create a decryptor to perform the stream transform.
ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
// prepend the IV
msEncrypt.Write(BitConverter.GetBytes(aesAlg.IV.Length), 0, sizeof(int));
msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
}
outStr = Convert.ToBase64String(msEncrypt.ToArray());
}
}
finally
{
// Clear the RijndaelManaged object.
if (aesAlg != null)
aesAlg.Clear();
}
// Return the encrypted bytes from the memory stream.
return outStr;
}
/// <summary>
/// Decrypt the given string. Assumes the string was encrypted using
/// EncryptStringAES(), using an identical sharedSecret.
/// </summary>
/// <param name="cipherText">The text to decrypt.</param>
/// <param name="sharedSecret">A password used to generate a key for decryption.</param>
public static string DecryptStringAES(string cipherText, string sharedSecret)
{
if (string.IsNullOrEmpty(cipherText))
throw new ArgumentNullException("cipherText");
if (string.IsNullOrEmpty(sharedSecret))
throw new ArgumentNullException("sharedSecret");
// Declare the RijndaelManaged object
// used to decrypt the data.
RijndaelManaged aesAlg = null;
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
try
{
// generate the key from the shared secret and the salt
Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);
// Create the streams used for decryption.
byte[] bytes = Convert.FromBase64String(cipherText);
using (MemoryStream msDecrypt = new MemoryStream(bytes))
{
// Create a RijndaelManaged object
// with the specified key and IV.
aesAlg = new RijndaelManaged();
aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
// Get the initialization vector from the encrypted stream
aesAlg.IV = ReadByteArray(msDecrypt);
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
finally
{
// Clear the RijndaelManaged object.
if (aesAlg != null)
aesAlg.Clear();
}
return plaintext;
}
private static byte[] ReadByteArray(Stream s)
{
byte[] rawLength = new byte[sizeof(int)];
if (s.Read(rawLength, 0, rawLength.Length) != rawLength.Length)
{
throw new SystemException("Stream did not contain properly formatted byte array");
}
byte[] buffer = new byte[BitConverter.ToInt32(rawLength, 0)];
if (s.Read(buffer, 0, buffer.Length) != buffer.Length)
{
throw new SystemException("Did not read byte array properly");
}
return buffer;
}
}
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