問題描述
我用 C# 編寫了一些 AES 加密代碼，但無法正確加密和解??密.如果我輸入test"作為密碼并且這個數(shù)據(jù)必須對所有人保密！"我收到以下異常:
I wrote some AES encryption code in C# and I am having trouble getting it to encrypt and decrypt properly. If I enter "test" as the passphrase and "This data must be kept secret from everyone!" I receive the following exception:
System.Security.Cryptography.CryptographicException: Padding is invalid and cannot be removed.
at System.Security.Cryptography.RijndaelManagedTransform.DecryptData(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount, Byte[]& outputBuffer, Int32 outputOffset, PaddingMode paddingMode, Boolean fLast)
at System.Security.Cryptography.RijndaelManagedTransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount)
at System.Security.Cryptography.CryptoStream.FlushFinalBlock()
at System.Security.Cryptography.CryptoStream.Dispose(Boolean disposing)
at System.IO.Stream.Close()
at System.IO.Stream.Dispose()
...
如果我輸入的內(nèi)容少于 16 個字符，我不會得到任何輸出.
And if I enter something less than 16 characters I get no output.
我認為我需要在加密中進行一些特殊處理，因為 AES 是一種分組密碼，但我不確定那是什么，而且我無法在網(wǎng)絡上找到任何示例來說明如何操作.這是我的代碼:
I believe I need some special handling in the encryption since AES is a block cipher, but I'm not sure exactly what that is, and I wasn't able to find any examples on the web showing how. Here is my code:
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
public static class DatabaseCrypto
{
public static EncryptedData Encrypt(string password, string data)
{
return DatabaseCrypto.Transform(true, password, data, null, null) as EncryptedData;
}
public static string Decrypt(string password, EncryptedData data)
{
return DatabaseCrypto.Transform(false, password, data.DataString, data.SaltString, data.MACString) as string;
}
private static object Transform(bool encrypt, string password, string data, string saltString, string macString)
{
using (AesManaged aes = new AesManaged())
{
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
int key_len = aes.KeySize / 8;
int iv_len = aes.BlockSize / 8;
const int salt_size = 8;
const int iterations = 8192;
byte[] salt = encrypt ? new byte[salt_size] : Convert.FromBase64String(saltString);
if (encrypt)
{
new RNGCryptoServiceProvider().GetBytes(salt);
}
byte[] bc_key = new Rfc2898DeriveBytes("BLK" + password, salt, iterations).GetBytes(key_len);
byte[] iv = new Rfc2898DeriveBytes("IV" + password, salt, iterations).GetBytes(iv_len);
byte[] mac_key = new Rfc2898DeriveBytes("MAC" + password, salt, iterations).GetBytes(16);
aes.Key = bc_key;
aes.IV = iv;
byte[] rawData = encrypt ? Encoding.UTF8.GetBytes(data) : Convert.FromBase64String(data);
using (ICryptoTransform transform = encrypt ? aes.CreateEncryptor() : aes.CreateDecryptor())
using (MemoryStream memoryStream = encrypt ? new MemoryStream() : new MemoryStream(rawData))
using (CryptoStream cryptoStream = new CryptoStream(memoryStream, transform, encrypt ? CryptoStreamMode.Write : CryptoStreamMode.Read))
{
if (encrypt)
{
cryptoStream.Write(rawData, 0, rawData.Length);
return new EncryptedData(salt, mac_key, memoryStream.ToArray());
}
else
{
byte[] originalData = new byte[rawData.Length];
int count = cryptoStream.Read(originalData, 0, originalData.Length);
return Encoding.UTF8.GetString(originalData, 0, count);
}
}
}
}
}
public class EncryptedData
{
public EncryptedData()
{
}
public EncryptedData(byte[] salt, byte[] mac, byte[] data)
{
this.Salt = salt;
this.MAC = mac;
this.Data = data;
}
public EncryptedData(string salt, string mac, string data)
{
this.SaltString = salt;
this.MACString = mac;
this.DataString = data;
}
public byte[] Salt
{
get;
set;
}
public string SaltString
{
get { return Convert.ToBase64String(this.Salt); }
set { this.Salt = Convert.FromBase64String(value); }
}
public byte[] MAC
{
get;
set;
}
public string MACString
{
get { return Convert.ToBase64String(this.MAC); }
set { this.MAC = Convert.FromBase64String(value); }
}
public byte[] Data
{
get;
set;
}
public string DataString
{
get { return Convert.ToBase64String(this.Data); }
set { this.Data = Convert.FromBase64String(value); }
}
}
static void ReadTest()
{
Console.WriteLine("Enter password: ");
string password = Console.ReadLine();
using (StreamReader reader = new StreamReader("aes.cs.txt"))
{
EncryptedData enc = new EncryptedData();
enc.SaltString = reader.ReadLine();
enc.MACString = reader.ReadLine();
enc.DataString = reader.ReadLine();
Console.WriteLine("The decrypted data was: " + DatabaseCrypto.Decrypt(password, enc));
}
}
static void WriteTest()
{
Console.WriteLine("Enter data: ");
string data = Console.ReadLine();
Console.WriteLine("Enter password: ");
string password = Console.ReadLine();
EncryptedData enc = DatabaseCrypto.Encrypt(password, data);
using (StreamWriter stream = new StreamWriter("aes.cs.txt"))
{
stream.WriteLine(enc.SaltString);
stream.WriteLine(enc.MACString);
stream.WriteLine(enc.DataString);
Console.WriteLine("The encrypted data was: " + enc.DataString);
}
}
推薦答案
在需要填充的模式(如 CBC)中使用像 AES 這樣的分組密碼時，您必須注意輸出始終是分組大小的倍數(shù).為了實現(xiàn)這一點，像 PKCS7 這樣的填充模式將在加密過程結束時向密碼添加一些字節(jié).但是你必須讓加密器知道何時結束.為此，您所要做的就是插入語句
When using a block cipher like AES in a mode that requires padding, like CBC, you must be aware that the output will always be a multiple of the block size. To accomplish this, padding modes like PKCS7 will add some bytes to the cipher at the end of the encryption process. But you have to let the encryptor know when the end occurs. To do so, all you have to do is insert the statement
cryptoStream.FlushFinalBlock();
之后
cryptoStream.Write(rawData, 0, rawData.Length);
PS:
也許它只是為了調(diào)試，但你的鹽生成方法每次都會生成完全相同的鹽.
Perhaps it is just for debugging, but your salt generation method generates the exact same salt every time.
這篇關于在 .NET 中使用 AES 加密 - CryptographicException 表示填充無效且無法刪除的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！