关于c＃：“填充无效，无法删除”使用AesManaged

“Padding is invalid and cannot be removed” using AesManaged

我正在尝试使用aesmanaged进行简单的加密/解密，但在尝试关闭解密流时，我总是遇到一个异常。这里的字符串得到了正确的加密和解密，然后在console.writeline打印正确的字符串后，我得到了cryptographicException"padding was invalid and cannot be removed"。

有什么想法吗？

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

MemoryStream ms = new MemoryStream();
byte[] rawPlaintext = Encoding.Unicode.GetBytes("This is annoying!");

using (Aes aes = new AesManaged())
{
aes.Padding = PaddingMode.PKCS7;
aes.Key = new byte[128/8];
aes.IV = new byte[128/8];

using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(),
CryptoStreamMode.Write))
{
cs.Write(rawPlaintext, 0, rawPlaintext.Length);
cs.FlushFinalBlock();
}

ms = new MemoryStream(ms.GetBuffer());
using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(),
CryptoStreamMode.Read))
{
byte[] rawData = new byte[rawPlaintext.Length];
int len = cs.Read(rawData, 0, rawPlaintext.Length);
string s = Encoding.Unicode.GetString(rawData);
Console.WriteLine(s);
}
}

诀窍是使用MemoryStream.ToArray()。我还修改了您的代码，以便它使用CryptoStream在加密和解密中进行写入。你不需要明确地调用CryptoStream.FlushFinalBlock()，因为你在using()语句中有它，而这个刷新将发生在Dispose()上。以下是我的作品。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

byte[] rawPlaintext = System.Text.Encoding.Unicode.GetBytes("This is all clear now!");

using (Aes aes = new AesManaged())
{
aes.Padding = PaddingMode.PKCS7;
aes.KeySize = 128; // in bits
aes.Key = new byte[128/8]; // 16 bytes for 128 bit encryption
aes.IV = new byte[128/8]; // AES needs a 16-byte IV
// Should set Key and IV here. Good approach: derive them from
// a password via Cryptography.Rfc2898DeriveBytes
byte[] cipherText= null;
byte[] plainText= null;

using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(rawPlaintext, 0, rawPlaintext.Length);
}

cipherText= ms.ToArray();
}

using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(cipherText, 0, cipherText.Length);
}

plainText = ms.ToArray();
}
string s = System.Text.Encoding.Unicode.GetString(plainText);
Console.WriteLine(s);
}

另外，我想您知道您需要显式设置aesmanaged实例的模式，并使用system.security.cryptography.rfc2898派生字节从密码和salt派生密钥和iv。

参见：-审美管理