1

我的安全团队希望我使用 AES256 密钥强度和 CBC 模式。我的代码只有在更改为 256 CBC 和块大小为 128 后现在输入长度为 32 个字母的输入明文时才有效。

如果我输入“这是一个测试”（不是 32 个字符长），我会收到：

System.Security.Cryptography.CryptographicException：输入数据不是一个完整的块。

如果我输入：“ABCDEFGHIJKLMNOPQRSTUVWXYZ000000”，就可以了！

我需要什么代码才能使用“这是一个测试”作为输入来完成这项工作。

下面的代码：

public byte[] EncryptStringToByte(string plainText, byte[] key, byte[]  vector)
{               
byte[] encrypted;                
using (AesCryptoServiceProvider aes = new AesCryptoServiceProvider())
{
    aes.BlockSize = 128;
    aes.KeySize = 256;
    aes.Mode = CipherMode.CBC;
    aes.Padding = PaddingMode.None;
    aes.Key = key;
    aes.IV = vector;

    // Create a decrytor to perform the stream transform.
    ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);

    // Create the streams used for encryption. 
    using (MemoryStream msEncrypt = new MemoryStream())
    {
        using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
        {
            using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
            {

                //Write all data to the stream.
                swEncrypt.Write(plainText);
            }
            encrypted = msEncrypt.ToArray();
        }
    }
    }
// Return the encrypted bytes from the memory stream. 
return encrypted;
}
4

1 回答 1

3

AES is a block cipher, so it only works on plaintexts that have exactly the size of one block. A mode of operation like CBC enables you to encrypt plaintexts that are a multiple of the block size. To encrypt plaintexts of arbitrary length a padding mode must be used.

A common mode used for block ciphers is PKCS#5/PKCS#7:

aes.Padding = PaddingMode.PKCS7;
于 2015-03-20T18:25:06.103 回答