在 C# 中加密和解密字符串
本文关键字:解密 字符串 加密 | 更新日期: 2023-09-27 18:31:08
C# 中满足以下条件的最现代(最佳)方法是什么?
string encryptedString = SomeStaticClass.Encrypt(sourceString);
string decryptedString = SomeStaticClass.Decrypt(encryptedString);
但是,只需最少的大惊小怪,包括盐、键、用 byte[] 胡思乱想等。
一直在谷歌上搜索并对我的发现感到困惑(您可以看到类似的 SO Q 列表,看看这是一个欺骗性的问题)。
> 更新 23/Dec/2015:由于这个答案似乎得到了很多赞成,我已经更新了它以修复愚蠢的错误,并根据评论和反馈总体上改进代码。 有关具体改进的列表,请参阅帖子末尾。
正如其他人所说,密码学并不简单,因此最好避免"推出自己的"加密算法。
但是,您可以围绕内置的 RijndaelManaged
加密类之类的东西"滚动自己的"包装类。
Rijndael是当前高级加密标准的算法名称,因此您肯定使用的是可以被视为"最佳实践"的算法。
RijndaelManaged
类确实通常需要你用字节数组、盐、键、初始化向量等来"乱搞",但这正是在你的"包装器"类中可以抽象出来的那种细节。
下面的类是我不久前写的,用于执行你所追求的那种东西,一个简单的方法调用,允许使用基于字符串的密码对一些基于字符串的明文进行加密,生成的加密字符串也表示为字符串。 当然,还有一种等效的方法可以使用相同的密码解密加密字符串。
与此代码的第一个版本不同,该版本每次都使用完全相同的盐和 IV 值,这个较新的版本每次都会生成随机盐和 IV 值。 由于 salt 和 IV 在给定字符串的加密和解密之间必须相同,因此在加密时将 salt 和 IV 附加到密文前面,并再次从中提取以执行解密。 这样做的结果是,使用完全相同的密码加密完全相同的明文每次都会给出完全不同的密文结果。
使用它的"优势"来自使用 RijndaelManaged
类为您执行加密,以及使用 System.Security.Cryptography
命名空间的 Rfc2898DeriveBytes 函数,该函数将使用标准和安全算法(特别是 PBKDF2)生成您的加密密钥基于您提供的基于字符串的密码。 (请注意,这是对第一个版本使用旧PBKDF1算法的改进)。
最后,重要的是要注意,这仍然是未经身份验证的加密。 加密本身仅提供隐私(即第三方不知道消息),而经过身份验证的加密旨在提供隐私和真实性(即收件人知道消息是由发件人发送的)。
在不知道您的确切要求的情况下,很难说这里的代码是否足够安全以满足您的需求,但是,它的制作是为了在相对简单的实现与"质量"之间提供良好的平衡。 例如,如果加密字符串的"接收方"直接从受信任的"发送方"接收字符串,则甚至可能不需要身份验证。
如果您需要更复杂的东西,并且提供经过身份验证的加密,请查看这篇文章以获取实现。
代码如下:
using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using System.Linq;
namespace EncryptStringSample
{
public static class StringCipher
{
// This constant is used to determine the keysize of the encryption algorithm in bits.
// We divide this by 8 within the code below to get the equivalent number of bytes.
private const int Keysize = 256;
// This constant determines the number of iterations for the password bytes generation function.
private const int DerivationIterations = 1000;
public static string Encrypt(string plainText, string passPhrase)
{
// Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
// so that the same Salt and IV values can be used when decrypting.
var saltStringBytes = Generate256BitsOfRandomEntropy();
var ivStringBytes = Generate256BitsOfRandomEntropy();
var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
var keyBytes = password.GetBytes(Keysize / 8);
using (var symmetricKey = new RijndaelManaged())
{
symmetricKey.BlockSize = 256;
symmetricKey.Mode = CipherMode.CBC;
symmetricKey.Padding = PaddingMode.PKCS7;
using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes))
{
using (var memoryStream = new MemoryStream())
{
using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
{
cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
cryptoStream.FlushFinalBlock();
// Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
var cipherTextBytes = saltStringBytes;
cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
memoryStream.Close();
cryptoStream.Close();
return Convert.ToBase64String(cipherTextBytes);
}
}
}
}
}
}
public static string Decrypt(string cipherText, string passPhrase)
{
// Get the complete stream of bytes that represent:
// [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
// Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
// Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
// Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();
using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
var keyBytes = password.GetBytes(Keysize / 8);
using (var symmetricKey = new RijndaelManaged())
{
symmetricKey.BlockSize = 256;
symmetricKey.Mode = CipherMode.CBC;
symmetricKey.Padding = PaddingMode.PKCS7;
using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
{
using (var memoryStream = new MemoryStream(cipherTextBytes))
{
using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
using (var streamReader = new StreamReader(cryptoStream, Encoding.UTF8))
{
return streamReader.ReadToEnd();
}
}
}
}
}
}
private static byte[] Generate256BitsOfRandomEntropy()
{
var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
using (var rngCsp = new RNGCryptoServiceProvider())
{
// Fill the array with cryptographically secure random bytes.
rngCsp.GetBytes(randomBytes);
}
return randomBytes;
}
}
}
上面的类可以非常简单地与类似于以下内容的代码一起使用:
using System;
namespace EncryptStringSample
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Please enter a password to use:");
string password = Console.ReadLine();
Console.WriteLine("Please enter a string to encrypt:");
string plaintext = Console.ReadLine();
Console.WriteLine("");
Console.WriteLine("Your encrypted string is:");
string encryptedstring = StringCipher.Encrypt(plaintext, password);
Console.WriteLine(encryptedstring);
Console.WriteLine("");
Console.WriteLine("Your decrypted string is:");
string decryptedstring = StringCipher.Decrypt(encryptedstring, password);
Console.WriteLine(decryptedstring);
Console.WriteLine("");
Console.WriteLine("Press any key to exit...");
Console.ReadLine();
}
}
}
(您可以在此处下载简单的VS2013示例解决方案(其中包括一些单元测试)。
更新 23/Dec/2015:代码的具体改进列表如下:
- 修复了一个愚蠢的错误,即加密和编码之间的编码不同解密。 由于生成盐和IV值的机制已经改变,不再需要编码。
- 由于 salt/IV 更改,前面的代码注释错误地指示 UTF8 编码 16 个字符的字符串产生 32 个字节,不再适用(因为不再需要编码)。 被取代的PBKDF1算法
- 的使用已被更现代的PBKDF2算法所取代。
- 密码派生现在被正确加盐,而以前根本没有加盐(另一个愚蠢的错误被压扁)。
using System.IO;
using System.Text;
using System.Security.Cryptography;
public static class EncryptionHelper
{
public static string Encrypt(string clearText)
{
string EncryptionKey = "abc123";
byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
using (Aes encryptor = Aes.Create())
{
Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
encryptor.Key = pdb.GetBytes(32);
encryptor.IV = pdb.GetBytes(16);
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(clearBytes, 0, clearBytes.Length);
cs.Close();
}
clearText = Convert.ToBase64String(ms.ToArray());
}
}
return clearText;
}
public static string Decrypt(string cipherText)
{
string EncryptionKey = "abc123";
cipherText = cipherText.Replace(" ", "+");
byte[] cipherBytes = Convert.FromBase64String(cipherText);
using (Aes encryptor = Aes.Create())
{
Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
encryptor.Key = pdb.GetBytes(32);
encryptor.IV = pdb.GetBytes(16);
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(cipherBytes, 0, cipherBytes.Length);
cs.Close();
}
cipherText = Encoding.Unicode.GetString(ms.ToArray());
}
}
return cipherText;
}
}
如果您的目标是 ASP.NET 尚不支持RijndaelManaged
的核心,则可以使用 IDataProtectionProvider
.
首先,将应用程序配置为使用数据保护:
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddDataProtection();
}
// ...
}
然后,您将能够注入IDataProtectionProvider
实例并使用它来加密/解密数据:
public class MyService : IService
{
private const string Purpose = "my protection purpose";
private readonly IDataProtectionProvider _provider;
public MyService(IDataProtectionProvider provider)
{
_provider = provider;
}
public string Encrypt(string plainText)
{
var protector = _provider.CreateProtector(Purpose);
return protector.Protect(plainText);
}
public string Decrypt(string cipherText)
{
var protector = _provider.CreateProtector(Purpose);
return protector.Unprotect(cipherText);
}
}
有关更多详细信息,请参阅此文章。
试试这个类:
public class DataEncryptor
{
TripleDESCryptoServiceProvider symm;
#region Factory
public DataEncryptor()
{
this.symm = new TripleDESCryptoServiceProvider();
this.symm.Padding = PaddingMode.PKCS7;
}
public DataEncryptor(TripleDESCryptoServiceProvider keys)
{
this.symm = keys;
}
public DataEncryptor(byte[] key, byte[] iv)
{
this.symm = new TripleDESCryptoServiceProvider();
this.symm.Padding = PaddingMode.PKCS7;
this.symm.Key = key;
this.symm.IV = iv;
}
#endregion
#region Properties
public TripleDESCryptoServiceProvider Algorithm
{
get { return symm; }
set { symm = value; }
}
public byte[] Key
{
get { return symm.Key; }
set { symm.Key = value; }
}
public byte[] IV
{
get { return symm.IV; }
set { symm.IV = value; }
}
#endregion
#region Crypto
public byte[] Encrypt(byte[] data) { return Encrypt(data, data.Length); }
public byte[] Encrypt(byte[] data, int length)
{
try
{
// Create a MemoryStream.
var ms = new MemoryStream();
// Create a CryptoStream using the MemoryStream
// and the passed key and initialization vector (IV).
var cs = new CryptoStream(ms,
symm.CreateEncryptor(symm.Key, symm.IV),
CryptoStreamMode.Write);
// Write the byte array to the crypto stream and flush it.
cs.Write(data, 0, length);
cs.FlushFinalBlock();
// Get an array of bytes from the
// MemoryStream that holds the
// encrypted data.
byte[] ret = ms.ToArray();
// Close the streams.
cs.Close();
ms.Close();
// Return the encrypted buffer.
return ret;
}
catch (CryptographicException ex)
{
Console.WriteLine("A cryptographic error occured: {0}", ex.Message);
}
return null;
}
public string EncryptString(string text)
{
return Convert.ToBase64String(Encrypt(Encoding.UTF8.GetBytes(text)));
}
public byte[] Decrypt(byte[] data) { return Decrypt(data, data.Length); }
public byte[] Decrypt(byte[] data, int length)
{
try
{
// Create a new MemoryStream using the passed
// array of encrypted data.
MemoryStream ms = new MemoryStream(data);
// Create a CryptoStream using the MemoryStream
// and the passed key and initialization vector (IV).
CryptoStream cs = new CryptoStream(ms,
symm.CreateDecryptor(symm.Key, symm.IV),
CryptoStreamMode.Read);
// Create buffer to hold the decrypted data.
byte[] result = new byte[length];
// Read the decrypted data out of the crypto stream
// and place it into the temporary buffer.
cs.Read(result, 0, result.Length);
return result;
}
catch (CryptographicException ex)
{
Console.WriteLine("A cryptographic error occured: {0}", ex.Message);
}
return null;
}
public string DecryptString(string data)
{
return Encoding.UTF8.GetString(Decrypt(Convert.FromBase64String(data))).TrimEnd(''0');
}
#endregion
}
并像这样使用它:
string message="A very secret message here.";
DataEncryptor keys=new DataEncryptor();
string encr=keys.EncryptString(message);
// later
string actual=keys.DecryptString(encr);
如果您需要将密码存储在内存中并希望对其进行加密,则应使用SecureString:
http://msdn.microsoft.com/en-us/library/system.security.securestring.aspx
对于更一般的用途,我会使用 FIPS 批准的算法,例如高级加密标准,以前称为 Rijndael。有关实现示例,请参阅此页面:
http://msdn.microsoft.com/en-us/library/system.security.cryptography.rijndael.aspx
正在寻找ProtectedData
类,该类使用用户的登录凭据加密数据。
我见过的最简单的加密方法是通过 RSA
查看其中的MSDN:http://msdn.microsoft.com/en-us/library/system.security.cryptography.rsacryptoserviceprovider.aspx
它确实涉及使用字节,但是当涉及到它时,您确实希望加密和解密很难弄清楚,否则很容易被黑客入侵。