如何在c#中加密和解密字符串?
当前回答
下面是一个简单的例子，在c#中使用AES CBC模式加密字符串，并使用随机IV和HMAC和密码派生密钥，以显示基本的移动部分:
private byte[] EncryptBytes(byte[] key, byte[] plaintext)
{
using (var cipher = new RijndaelManaged { Key = key })
{
using (var encryptor = cipher.CreateEncryptor())
{
var ciphertext = encryptor.TransformFinalBlock(plaintext, 0, plaintext.Length);
// IV is prepended to ciphertext
return cipher.IV.Concat(ciphertext).ToArray();
}
}
}
private byte[] DecryptBytes(byte[] key, byte[] packed)
{
using (var cipher = new RijndaelManaged { Key = key })
{
int ivSize = cipher.BlockSize / 8;
cipher.IV = packed.Take(ivSize).ToArray();
using (var encryptor = cipher.CreateDecryptor())
{
return encryptor.TransformFinalBlock(packed, ivSize, packed.Length - ivSize);
}
}
}
private byte[] AddMac(byte[] key, byte[] data)
{
using (var hmac = new HMACSHA256(key))
{
var macBytes = hmac.ComputeHash(data);
// HMAC is appended to data
return data.Concat(macBytes).ToArray();
}
}
private bool BadMac(byte[] found, byte[] computed)
{
int mismatch = 0;
// Aim for consistent timing regardless of inputs
for (int i = 0; i < found.Length; i++)
{
mismatch += found[i] == computed[i] ? 0 : 1;
}
return mismatch != 0;
}
private byte[] RemoveMac(byte[] key, byte[] data)
{
using (var hmac = new HMACSHA256(key))
{
int macSize = hmac.HashSize / 8;
var packed = data.Take(data.Length - macSize).ToArray();
var foundMac = data.Skip(packed.Length).ToArray();
var computedMac = hmac.ComputeHash(packed);
if (this.BadMac(foundMac, computedMac))
{
throw new Exception("Bad MAC");
}
return packed;
}
}
private List<byte[]> DeriveTwoKeys(string password)
{
var salt = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var kdf = new Rfc2898DeriveBytes(password, salt, 10000);
var bytes = kdf.GetBytes(32); // Two keys 128 bits each
return new List<byte[]> { bytes.Take(16).ToArray(), bytes.Skip(16).ToArray() };
}
public byte[] EncryptString(string password, String message)
{
var keys = this.DeriveTwoKeys(password);
var plaintext = Encoding.UTF8.GetBytes(message);
var packed = this.EncryptBytes(keys[0], plaintext);
return this.AddMac(keys[1], packed);
}
public String DecryptString(string password, byte[] secret)
{
var keys = this.DeriveTwoKeys(password);
var packed = this.RemoveMac(keys[1], secret);
var plaintext = this.DecryptBytes(keys[0], packed);
return Encoding.UTF8.GetString(plaintext);
}
public void Example()
{
var password = "correcthorsebatterystaple";
var secret = this.EncryptString(password, "Hello World");
Console.WriteLine("secret: " + BitConverter.ToString(secret));
var recovered = this.DecryptString(password, secret);
Console.WriteLine(recovered);
}
其他回答
下面是一个简单的例子，在c#中使用AES CBC模式加密字符串，并使用随机IV和HMAC和密码派生密钥，以显示基本的移动部分:
private byte[] EncryptBytes(byte[] key, byte[] plaintext)
{
using (var cipher = new RijndaelManaged { Key = key })
{
using (var encryptor = cipher.CreateEncryptor())
{
var ciphertext = encryptor.TransformFinalBlock(plaintext, 0, plaintext.Length);
// IV is prepended to ciphertext
return cipher.IV.Concat(ciphertext).ToArray();
}
}
}
private byte[] DecryptBytes(byte[] key, byte[] packed)
{
using (var cipher = new RijndaelManaged { Key = key })
{
int ivSize = cipher.BlockSize / 8;
cipher.IV = packed.Take(ivSize).ToArray();
using (var encryptor = cipher.CreateDecryptor())
{
return encryptor.TransformFinalBlock(packed, ivSize, packed.Length - ivSize);
}
}
}
private byte[] AddMac(byte[] key, byte[] data)
{
using (var hmac = new HMACSHA256(key))
{
var macBytes = hmac.ComputeHash(data);
// HMAC is appended to data
return data.Concat(macBytes).ToArray();
}
}
private bool BadMac(byte[] found, byte[] computed)
{
int mismatch = 0;
// Aim for consistent timing regardless of inputs
for (int i = 0; i < found.Length; i++)
{
mismatch += found[i] == computed[i] ? 0 : 1;
}
return mismatch != 0;
}
private byte[] RemoveMac(byte[] key, byte[] data)
{
using (var hmac = new HMACSHA256(key))
{
int macSize = hmac.HashSize / 8;
var packed = data.Take(data.Length - macSize).ToArray();
var foundMac = data.Skip(packed.Length).ToArray();
var computedMac = hmac.ComputeHash(packed);
if (this.BadMac(foundMac, computedMac))
{
throw new Exception("Bad MAC");
}
return packed;
}
}
private List<byte[]> DeriveTwoKeys(string password)
{
var salt = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
var kdf = new Rfc2898DeriveBytes(password, salt, 10000);
var bytes = kdf.GetBytes(32); // Two keys 128 bits each
return new List<byte[]> { bytes.Take(16).ToArray(), bytes.Skip(16).ToArray() };
}
public byte[] EncryptString(string password, String message)
{
var keys = this.DeriveTwoKeys(password);
var plaintext = Encoding.UTF8.GetBytes(message);
var packed = this.EncryptBytes(keys[0], plaintext);
return this.AddMac(keys[1], packed);
}
public String DecryptString(string password, byte[] secret)
{
var keys = this.DeriveTwoKeys(password);
var packed = this.RemoveMac(keys[1], secret);
var plaintext = this.DecryptBytes(keys[0], packed);
return Encoding.UTF8.GetString(plaintext);
}
public void Example()
{
var password = "correcthorsebatterystaple";
var secret = this.EncryptString(password, "Hello World");
Console.WriteLine("secret: " + BitConverter.ToString(secret));
var recovered = this.DecryptString(password, secret);
Console.WriteLine(recovered);
}
BouncyCastle是一个很棒的。net加密库，它可以作为Nuget包安装到你的项目中。比起目前System.Security.Cryptography库中可用的东西，我更喜欢它。它为你提供了更多可用算法的选择，并为这些算法提供了更多的模式。
这是一个TwoFish实现的例子，它是由Bruce Schneier(我们所有偏执的人的英雄)编写的。这是一个像Rijndael一样的对称算法 (又名AES)。它是AES标准的三个最终入选者之一，是Bruce Schneier编写的另一个著名算法BlowFish的兄弟姐妹。
使用bouncycastle的第一件事是创建一个加密器类，这将使它更容易在库中实现其他块密码。下面的加密器类接受一个泛型参数T，其中T实现了IBlockCipher，并有一个默认构造函数。
UPDATE: Due to popular demand I have decided to implement generating a random IV as well as include an HMAC into this class. Although from a style perspective this goes against the SOLID principle of single responsibility, because of the nature of what this class does I reniged. This class will now take two generic parameters, one for the cipher and one for the digest. It automatically generates the IV using RNGCryptoServiceProvider to provide good RNG entropy, and allows you to use whatever digest algorithm you want from BouncyCastle to generate the MAC.
using System;
using System.Security.Cryptography;
using System.Text;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Macs;
using Org.BouncyCastle.Crypto.Modes;
using Org.BouncyCastle.Crypto.Paddings;
using Org.BouncyCastle.Crypto.Parameters;
public sealed class Encryptor<TBlockCipher, TDigest>
where TBlockCipher : IBlockCipher, new()
where TDigest : IDigest, new()
{
private Encoding encoding;
private IBlockCipher blockCipher;
private BufferedBlockCipher cipher;
private HMac mac;
private byte[] key;
public Encryptor(Encoding encoding, byte[] key, byte[] macKey)
{
this.encoding = encoding;
this.key = key;
this.Init(key, macKey, new Pkcs7Padding());
}
public Encryptor(Encoding encoding, byte[] key, byte[] macKey, IBlockCipherPadding padding)
{
this.encoding = encoding;
this.key = key;
this.Init(key, macKey, padding);
}
private void Init(byte[] key, byte[] macKey, IBlockCipherPadding padding)
{
this.blockCipher = new CbcBlockCipher(new TBlockCipher());
this.cipher = new PaddedBufferedBlockCipher(this.blockCipher, padding);
this.mac = new HMac(new TDigest());
this.mac.Init(new KeyParameter(macKey));
}
public string Encrypt(string plain)
{
return Convert.ToBase64String(EncryptBytes(plain));
}
public byte[] EncryptBytes(string plain)
{
byte[] input = this.encoding.GetBytes(plain);
var iv = this.GenerateIV();
var cipher = this.BouncyCastleCrypto(true, input, new ParametersWithIV(new KeyParameter(key), iv));
byte[] message = CombineArrays(iv, cipher);
this.mac.Reset();
this.mac.BlockUpdate(message, 0, message.Length);
byte[] digest = new byte[this.mac.GetUnderlyingDigest().GetDigestSize()];
this.mac.DoFinal(digest, 0);
var result = CombineArrays(digest, message);
return result;
}
public byte[] DecryptBytes(byte[] bytes)
{
// split the digest into component parts
var digest = new byte[this.mac.GetUnderlyingDigest().GetDigestSize()];
var message = new byte[bytes.Length - digest.Length];
var iv = new byte[this.blockCipher.GetBlockSize()];
var cipher = new byte[message.Length - iv.Length];
Buffer.BlockCopy(bytes, 0, digest, 0, digest.Length);
Buffer.BlockCopy(bytes, digest.Length, message, 0, message.Length);
if (!IsValidHMac(digest, message))
{
throw new CryptoException();
}
Buffer.BlockCopy(message, 0, iv, 0, iv.Length);
Buffer.BlockCopy(message, iv.Length, cipher, 0, cipher.Length);
byte[] result = this.BouncyCastleCrypto(false, cipher, new ParametersWithIV(new KeyParameter(key), iv));
return result;
}
public string Decrypt(byte[] bytes)
{
return this.encoding.GetString(DecryptBytes(bytes));
}
public string Decrypt(string cipher)
{
return this.Decrypt(Convert.FromBase64String(cipher));
}
private bool IsValidHMac(byte[] digest, byte[] message)
{
this.mac.Reset();
this.mac.BlockUpdate(message, 0, message.Length);
byte[] computed = new byte[this.mac.GetUnderlyingDigest().GetDigestSize()];
this.mac.DoFinal(computed, 0);
return AreEqual(digest,computed);
}
private static bool AreEqual(byte [] digest, byte[] computed)
{
if(digest.Length != computed.Length)
{
return false;
}
int result = 0;
for (int i = 0; i < digest.Length; i++)
{
// compute equality of all bytes before returning.
// helps prevent timing attacks:
// https://codahale.com/a-lesson-in-timing-attacks/
result |= digest[i] ^ computed[i];
}
return result == 0;
}
private byte[] BouncyCastleCrypto(bool forEncrypt, byte[] input, ICipherParameters parameters)
{
try
{
cipher.Init(forEncrypt, parameters);
return this.cipher.DoFinal(input);
}
catch (CryptoException)
{
throw;
}
}
private byte[] GenerateIV()
{
using (var provider = new RNGCryptoServiceProvider())
{
// 1st block
byte[] result = new byte[this.blockCipher.GetBlockSize()];
provider.GetBytes(result);
return result;
}
}
private static byte[] CombineArrays(byte[] source1, byte[] source2)
{
byte[] result = new byte[source1.Length + source2.Length];
Buffer.BlockCopy(source1, 0, result, 0, source1.Length);
Buffer.BlockCopy(source2, 0, result, source1.Length, source2.Length);
return result;
}
}
接下来只需在新类上调用加密和解密方法，下面是使用twofish的示例:
var encrypt = new Encryptor<TwofishEngine, Sha1Digest>(Encoding.UTF8, key, hmacKey);
string cipher = encrypt.Encrypt("TEST");
string plainText = encrypt.Decrypt(cipher);
替换像TripleDES这样的分组密码也很容易:
var des = new Encryptor<DesEdeEngine, Sha1Digest>(Encoding.UTF8, key, hmacKey);
string cipher = des.Encrypt("TEST");
string plainText = des.Decrypt(cipher);
最后，如果你想使用AES和SHA256 HMAC，你可以做以下事情:
var aes = new Encryptor<AesEngine, Sha256Digest>(Encoding.UTF8, key, hmacKey);
cipher = aes.Encrypt("TEST");
plainText = aes.Decrypt(cipher);
The hardest part about encryption actually deals with the keys and not the algorithms. You'll have to think about where you store your keys, and if you have to, how you exchange them. These algorithms have all withstood the test of time, and are extremely hard to break. Someone who wants to steal information from you isn't going to spend eternity doing cryptanalysis on your messages, they're going to try to figure out what or where your key is. So #1 choose your keys wisely, #2 store them in a safe place, if you use a web.config and IIS then you can encrypt parts of the the web.config, and finally if you have to exchange keys make sure that your protocol for exchanging the key is secure.
更新2 改变比较方法以减轻定时攻击。点击这里查看更多信息http://codahale.com/a-lesson-in-timing-attacks/。还更新到默认PKCS7填充，并添加了新的构造函数，以允许最终用户选择他们想要使用的填充。感谢@CodesInChaos的建议。
我想给你我的贡献，与我的代码AES Rfc2898DeriveBytes(这里的文档)算法，写在c#(。NET框架4)，并且完全适用于有限的平台，如Windows Phone 7.0+的.NET紧凑框架(不是所有平台都支持.NET框架的每一种编码方法!)
我希望这能帮助到任何人!
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
public static class Crypto
{
private static readonly byte[] IVa = new byte[] { 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x11, 0x11, 0x12, 0x13, 0x14, 0x0e, 0x16, 0x17 };
public static string Encrypt(this string text, string salt)
{
try
{
using (Aes aes = new AesManaged())
{
Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(Encoding.UTF8.GetString(IVa, 0, IVa.Length), Encoding.UTF8.GetBytes(salt));
aes.Key = deriveBytes.GetBytes(128 / 8);
aes.IV = aes.Key;
using (MemoryStream encryptionStream = new MemoryStream())
{
using (CryptoStream encrypt = new CryptoStream(encryptionStream, aes.CreateEncryptor(), CryptoStreamMode.Write))
{
byte[] cleanText = Encoding.UTF8.GetBytes(text);
encrypt.Write(cleanText, 0, cleanText.Length);
encrypt.FlushFinalBlock();
}
byte[] encryptedData = encryptionStream.ToArray();
string encryptedText = Convert.ToBase64String(encryptedData);
return encryptedText;
}
}
}
catch
{
return String.Empty;
}
}
public static string Decrypt(this string text, string salt)
{
try
{
using (Aes aes = new AesManaged())
{
Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(Encoding.UTF8.GetString(IVa, 0, IVa.Length), Encoding.UTF8.GetBytes(salt));
aes.Key = deriveBytes.GetBytes(128 / 8);
aes.IV = aes.Key;
using (MemoryStream decryptionStream = new MemoryStream())
{
using (CryptoStream decrypt = new CryptoStream(decryptionStream, aes.CreateDecryptor(), CryptoStreamMode.Write))
{
byte[] encryptedData = Convert.FromBase64String(text);
decrypt.Write(encryptedData, 0, encryptedData.Length);
decrypt.Flush();
}
byte[] decryptedData = decryptionStream.ToArray();
string decryptedText = Encoding.UTF8.GetString(decryptedData, 0, decryptedData.Length);
return decryptedText;
}
}
}
catch
{
return String.Empty;
}
}
}
}
加密
public string EncryptString(string inputString)
{
MemoryStream memStream = null;
try
{
byte[] key = { };
byte[] IV = { 12, 21, 43, 17, 57, 35, 67, 27 };
string encryptKey = "aXb2uy4z"; // MUST be 8 characters
key = Encoding.UTF8.GetBytes(encryptKey);
byte[] byteInput = Encoding.UTF8.GetBytes(inputString);
DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
memStream = new MemoryStream();
ICryptoTransform transform = provider.CreateEncryptor(key, IV);
CryptoStream cryptoStream = new CryptoStream(memStream, transform, CryptoStreamMode.Write);
cryptoStream.Write(byteInput, 0, byteInput.Length);
cryptoStream.FlushFinalBlock();
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
return Convert.ToBase64String(memStream.ToArray());
}
解密:
public string DecryptString(string inputString)
{
MemoryStream memStream = null;
try
{
byte[] key = { };
byte[] IV = { 12, 21, 43, 17, 57, 35, 67, 27 };
string encryptKey = "aXb2uy4z"; // MUST be 8 characters
key = Encoding.UTF8.GetBytes(encryptKey);
byte[] byteInput = new byte[inputString.Length];
byteInput = Convert.FromBase64String(inputString);
DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
memStream = new MemoryStream();
ICryptoTransform transform = provider.CreateDecryptor(key, IV);
CryptoStream cryptoStream = new CryptoStream(memStream, transform, CryptoStreamMode.Write);
cryptoStream.Write(byteInput, 0, byteInput.Length);
cryptoStream.FlushFinalBlock();
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
Encoding encoding1 = Encoding.UTF8;
return encoding1.GetString(memStream.ToArray());
}
支持mattmanser的回答。下面是一个使用MachineKey类加密/解密URL安全值的示例。
Something to bear in mind, as mentioned before, this will use Machine config settings (https://msdn.microsoft.com/en-us/library/ff649308.aspx). You can set encryption and decryption key/algorithm manually (you might need this specially if your site is running on multiple servers) in web.config file. You can generate keys from IIS (see here: https://blogs.msdn.microsoft.com/vijaysk/2009/05/13/iis-7-tip-10-you-can-generate-machine-keys-from-the-iis-manager/) or can use an online machine key generator like: http://www.developerfusion.com/tools/generatemachinekey/
private static readonly UTF8Encoding Encoder = new UTF8Encoding();
public static string Encrypt(string unencrypted)
{
if (string.IsNullOrEmpty(unencrypted))
return string.Empty;
try
{
var encryptedBytes = MachineKey.Protect(Encoder.GetBytes(unencrypted));
if (encryptedBytes != null && encryptedBytes.Length > 0)
return HttpServerUtility.UrlTokenEncode(encryptedBytes);
}
catch (Exception)
{
return string.Empty;
}
return string.Empty;
}
public static string Decrypt(string encrypted)
{
if (string.IsNullOrEmpty(encrypted))
return string.Empty;
try
{
var bytes = HttpServerUtility.UrlTokenDecode(encrypted);
if (bytes != null && bytes.Length > 0)
{
var decryptedBytes = MachineKey.Unprotect(bytes);
if(decryptedBytes != null && decryptedBytes.Length > 0)
return Encoder.GetString(decryptedBytes);
}
}
catch (Exception)
{
return string.Empty;
}
return string.Empty;
}
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