代码笔记 | 用C#实现跟CI里面的加密解密

using System;
using System.Text;
using System.IO;
using System.Security.Cryptography;

namespace CI
{
class CI_Encrypt
{
private string key;
private string hash_type = "sha1";

public CI_Encrypt(string key = "")
{
if(key.Length > 0)
{
this.key = key;
}
}
public string encode(string data)
{
RijndaelManaged aes = new RijndaelManaged();
aes.KeySize = 256;
aes.BlockSize = 256;
aes.Padding = PaddingMode.Zeros;
aes.Mode = CipherMode.CBC;

aes.Key = this.get_key(key);
aes.GenerateIV();
var _IV = aes.IV;

byte[] buffer;

ICryptoTransform AESEncrypt = aes.CreateEncryptor(aes.Key, aes.IV);
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, AESEncrypt, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{

//Write all data to the stream.
swEncrypt.Write(data);
}
buffer = msEncrypt.ToArray();
}
}

var enc = new byte [ _IV.Length + buffer.Length ];

Array.Copy(_IV,enc ,_IV.Length);
Array.Copy(buffer,0,enc,_IV.Length,buffer.Length);

return this.add_cipher_noise(enc);
}

public string decode(string data)
{
string plainText;
byte[] _enc_data = this.remove_cipher_noise(Convert.FromBase64String(data));
using (RijndaelManaged aes = new RijndaelManaged())
{
aes.KeySize = 256;
aes.BlockSize = 256;
aes.Padding = PaddingMode.Zeros;
aes.Mode = CipherMode.CBC;
aes.Key = this.get_key(key);
var _IV = new byte[aes.IV.Length];
Array.Copy(_enc_data, _IV, _IV.Length);
aes.IV = _IV;
var endata = new byte[_enc_data.Length - aes.IV.Length];
Array.Copy(_enc_data, aes.IV.Length, endata, 0, endata.Length);

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

// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(endata))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{

// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plainText = srDecrypt.ReadToEnd();
}
}
}

}
return plainText;
}

public string add_cipher_noise(byte[] data)
{
string hashkey = this.hash(System.Text.Encoding.Default.GetString(this.get_key(this.key)));
char[] keyChar = hashkey.ToCharArray();
byte[] encrpytData = new byte[data.Length];
for (int i = 0, j = 0; i < data.Length; i++, j++)
{
if (j >= hashkey.Length)
{
j = 0;
}
var temp = (((int)data[i] + (int)keyChar[j]) % 256);
encrpytData[i] = (byte)temp;
}
return System.Convert.ToBase64String(encrpytData);
}

public byte[] remove_cipher_noise(byte[] data)
{
string hashkey = this.hash(System.Text.Encoding.Default.GetString(this.get_key(this.key)));
char[] keyChar = hashkey.ToCharArray();
byte[] encrpytData = new byte[data.Length];
int temp;

for (int i = 0, j = 0; i < data.Length; i++, j++)
{
if (j >= hashkey.Length)
{
j = 0;
}
temp = (int)data[i] - (int)keyChar[j];
if(temp < 0)
{
temp += 256;
}
encrpytData[i] = (byte)temp;
}
return encrpytData;
}

private string hash(string key)
{
byte[] hashBytes;
if (this.hash_type == "sha1")
{
SHA1 sha = new SHA1CryptoServiceProvider();
hashBytes = (sha.ComputeHash(System.Text.Encoding.Default.GetBytes(key)));
}
else
{
MD5 md5 = new MD5CryptoServiceProvider();
hashBytes = (md5.ComputeHash(System.Text.Encoding.Default.GetBytes(key)));
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < hashBytes.Length; i++)
{
sb.Append(hashBytes[i].ToString("X2"));
}
return sb.ToString().ToLower();
}

private byte[] get_key(string key)
{
MD5 md5 = new MD5CryptoServiceProvider();
byte[] hashBytes = (md5.ComputeHash(System.Text.Encoding.UTF8.GetBytes(key)));
StringBuilder sb = new StringBuilder();
for (int i = 0; i < hashBytes.Length; i++)
{
sb.Append(hashBytes[i].ToString("X2"));
}
return System.Text.Encoding.Default.GetBytes(sb.ToString().ToLower());
}
}
}