[英]Example code PHP / C# AES encryption - random IV
I found an implementation for AES encryption/decryption that's supposed to work in PHP and C#: https://odan.github.io/2017/08/10/aes-256-encryption-and-decryption-in-php-and-csharp.html我发现了一个 AES 加密/解密的实现,它应该在 PHP 和 C# 中工作: https : //odan.github.io/2017/08/10/aes-256-encryption-and-decryption-in-php-and- csharp.html
However, in this example, the IV is always 0, which is not good.但是,在本例中,IV 始终为 0,这并不好。 So, as the author suggests, I use the openssl_random_pseudo_bytes() function:
所以,正如作者所建议的,我使用 openssl_random_pseudo_bytes() 函数:
$ivlen = openssl_cipher_iv_length($method);
$iv = openssl_random_pseudo_bytes($ivlen);
However, the problem now is, that I have to store the IV somewhere so that the C# app can use it for decryption.但是,现在的问题是,我必须将 IV 存储在某处,以便 C# 应用程序可以使用它进行解密。 My idea was to base64_encode it and prepend it to the encrypted message with ":" separating both, so that I can simply split the string, then base64 decode it in C# and can use the IV.
我的想法是对它进行 base64_encode 并将其添加到加密消息中,并使用“:”将两者分开,这样我就可以简单地拆分字符串,然后在 C# 中对其进行 base64 解码并可以使用 IV。 However, this does not work.
但是,这不起作用。 This is the code:
这是代码:
public string DecryptString(string cipherText, byte[] key, byte[] iv)
{
// Instantiate a new Aes object to perform string symmetric encryption
Aes encryptor = Aes.Create();
encryptor.Mode = CipherMode.CBC;
// Set key and IV
byte[] aesKey = new byte[32];
Array.Copy(key, 0, aesKey, 0, 32);
encryptor.Key = aesKey;
encryptor.IV = iv;
// Instantiate a new MemoryStream object to contain the encrypted bytes
MemoryStream memoryStream = new MemoryStream();
// Instantiate a new encryptor from our Aes object
ICryptoTransform aesDecryptor = encryptor.CreateDecryptor();
// Instantiate a new CryptoStream object to process the data and write it to the
// memory stream
CryptoStream cryptoStream = new CryptoStream(memoryStream, aesDecryptor, CryptoStreamMode.Write);
// Will contain decrypted plaintext
string plainText = String.Empty;
try {
// Convert the ciphertext string into a byte array
byte[] cipherBytes = Convert.FromBase64String(cipherText);
// Decrypt the input ciphertext string
cryptoStream.Write(cipherBytes, 0, cipherBytes . Length);
// Complete the decryption process
cryptoStream.FlushFinalBlock();
// Convert the decrypted data from a MemoryStream to a byte array
byte[] plainBytes = memoryStream.ToArray();
// Convert the decrypted byte array to string
plainText = Encoding.ASCII.GetString(plainBytes, 0, plainBytes.Length);
} finally {
// Close both the MemoryStream and the CryptoStream
memoryStream.Close();
cryptoStream.Close();
}
// Return the decrypted data as a string
return plainText;
}
And this is how I try to call the function with the IV prepended to the encrypted message:这就是我尝试在加密消息前添加 IV 来调用函数的方式:
private void btnDecrypt_Click(object sender, EventArgs e)
{
string encrypted = txtEncrypted.Text;
string password = txtPW.Text;
string[] temp = encrypted.Split(":".ToCharArray());
string iv_str = temp[0];
encrypted = temp[1];
SHA256 mySHA256 = SHA256Managed.Create();
byte[] key = mySHA256.ComputeHash(Encoding.ASCII.GetBytes(password));
iv_str = Encoding.Default.GetString(Convert.FromBase64String(iv_str));
byte[] iv = Encoding.ASCII.GetBytes(iv_str);
txtDecrypted.Text = this.DecryptString(encrypted, key, iv);
}
Doesn't work.不起作用。 It decrypts something, but that's just gibberish and not the message I encrypted in PHP.
它解密了一些东西,但这只是胡言乱语,而不是我用 PHP 加密的消息。 I think it has to do with the IV somehow.
我认为这与 IV 有某种关系。
@Topaco: Thank you very much... now I see what my mistake was. @Topaco:非常感谢……现在我明白我的错误是什么了。 It works now with generated IV.
它现在适用于生成的 IV。 By the way, two more questions on the strength of the encryption:
顺便说一下,还有两个关于加密强度的问题:
Is it ok to use the following function to generate an IV (GenerateIV() for some reason won't work):是否可以使用以下函数生成 IV(GenerateIV() 由于某种原因不起作用):
byte[] iv = new byte[16];字节[] iv = 新字节[16]; Random rnd = new Random();
随机 rnd = 新随机(); rnd.NextBytes(iv);
rnd.NextBytes(iv);
I added a randomly generated salt to the password of the user, so that the key is a hash from the user password and a salt.我在用户的密码中添加了一个随机生成的盐,因此密钥是用户密码和盐的散列。 I also prepend the salt, together with the now randomly generated IV, to the message.
我还将盐与现在随机生成的 IV 一起添加到消息中。 Then for the decryption process I use the prepended salt and the key the user enters.
然后对于解密过程,我使用预先添加的盐和用户输入的密钥。 Works so far.
到目前为止工作。 But does it weaken the encryption?
但是它会削弱加密吗? No, right?
没有权利?
Thank you very much.非常感谢。
// Edit: Code format doesn't work, don't know why. // 编辑:代码格式不起作用,不知道为什么。
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