为我的AES方法创建一个字节数组有多少个字符？ [英] How many characters to create a byte array for my AES method?

问题描述

我在这里使用AES方法： http ：//msdn.microsoft.com/en-us/library/system.security.cryptography.rijndaelmanaged.aspx

I am using the AES methods here: http://msdn.microsoft.com/en-us/library/system.security.cryptography.rijndaelmanaged.aspx

我想要一个字符串值我将转换为字节数组并传递给AES加密方法。字符串应该有多少字符来产生方法期望的正确的字节数组大小？

I want to have a string value that I will convert to byte array and pass it to the AES encrypt method. How many characters should the string be to produce the correct byte array size that the method expects?

static byte[] encryptStringToBytes_AES(string plainText, byte[] Key, byte[] IV)
    {
        // Check arguments.
        if (plainText == null || plainText.Length <= 0)
            throw new ArgumentNullException("plainText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");

        // Declare the stream used to encrypt to an in memory
        // array of bytes.
        MemoryStream msEncrypt = null;

        // Declare the RijndaelManaged object
        // used to encrypt the data.
        RijndaelManaged aesAlg = null;

        try
        {
            // Create a RijndaelManaged object
            // with the specified key and IV.
            aesAlg = new RijndaelManaged();
            aesAlg.Key = Key;
            aesAlg.IV = IV;

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

            // Create the streams used for encryption.
            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);
                }
            }

        }
        finally
        {

            // Clear the RijndaelManaged object.
            if (aesAlg != null)
                aesAlg.Clear();
        }

        // Return the encrypted bytes from the memory stream.
        return msEncrypt.ToArray();

    }

推荐答案

的纯文本没关系。只要确保使用完全相同的IV和Key以及decryptStringFromBytes_AES（byte [] cipherText，byte [] Key，byte [] IV）方法中的加密字节。这将返回给您输入的纯文本。

The size of the plain text does not matter. Just make sure you use the exact same IV and Key along with the encrypted bytes in the decryptStringFromBytes_AES(byte[] cipherText, byte[] Key, byte[] IV) method. That will return back to you the entered plain text.

例如：

string plain_text = "Cool this works";
byte[] iv = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
                                           0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F};
byte[] key = new byte[] { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
                                           0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF };
byte[] encrytped_text = encryptStringToBytes_AES(plain_text, key, iv);
string plain_text_again = decryptStringFromBytes_AES(encrypted_text, key, iv);

这里你应该看到纯文本和纯文本 - 再次是一样的。现在开始将plain_text更改为任何您想要的内容，并且看到这样可以正常工作。

Here you should see that plain-text and plain-text-again are the same. Now go ahead and change plain_text to anything you want and see that this works fine.

RijndaelManaged的默认值为：

BlockSize：128 < br>
KeySize：256

模式：CipherMode.CBC

填充：PaddingMode.PKCS7

The default values for RijndaelManaged are:
BlockSize: 128
KeySize: 256
Mode: CipherMode.CBC
Padding: PaddingMode.PKCS7

有效的IV大小是：

128,192,256位（这是BlockSize，请确保将其设置为您正在使用的大小IV）

有效的密钥大小是：

128,192,256位（这是KeySize，请确保将其设置为您正在使用的大小键）

The valid IV sizes are:
128, 192, 256 bits (This is the BlockSize, make sure to set it to size IV you are using)
The valid Key sizes are:
128, 192, 256 bits (This is the KeySize, make sure to set it to the size key you are using)

这意味着byte [] iv可以是16,24或32字节（在我上面的例子中是16字节），byte []键也可以是16,24或32字节（在我上面的例子中它的16字节）。

This means that the byte[] iv can be 16, 24, or 32 bytes (in my above example its 16 bytes) and the byte[] key can also be 16, 24, or 32 bytes (in my above example its 16 bytes).

希望有所帮助。

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