my task is to decrypt data encrypted in C# using Php. I try to use the phpseclib library. So here is the existing code that is used in C# to encrypt :
public static String EncryptMyText(string clearText, string Password) { if (clearText.Length == 0) return ""; byte[] clearBytes = System.Text.Encoding.UTF8.GetBytes(clearText); // second parameter is "Ivan Medvedev" in string PasswordDeriveBytes pdb = new PasswordDeriveBytes(Password, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 }); byte[] encryptedData = Encrypt(clearBytes, pdb.GetBytes(32), pdb.GetBytes(16)); return Convert.ToBase64String(encryptedData); } public static byte[] Encrypt(byte[] clearData, byte[] Key, byte[] IV) { try { MemoryStream ms = new MemoryStream(); Rijndael alg = Rijndael.Create(); alg.Key = Key; alg.IV = IV; CryptoStream cs = new CryptoStream(ms, alg.CreateEncryptor(), CryptoStreamMode.Write); cs.Write(clearData, 0, clearData.Length); cs.Close(); byte[] encryptedData = ms.ToArray(); return encryptedData; } catch (Exception ex) { string message = ex.Message; } return null; } EncryptMyText("sometext", "xxxxxxxxxxxxxxx"); // password have 15 characters length It is not possible to change this code. So here is what I've tried using phpseclib :
$key = "xxxxxxxxxxxxxxx"; $salt = "Ivan Medvedev"; $cipher = new Rijndael(); $cipher->setPassword($cle, 'pbkdf1', 'sha1', $salt); $cipher->decrypt(base64_decode("someCryptedText")); At this point, the code breaks with an Exception "Derived key too long" raised on setPassword() call.
I tried many things such as changing blockLength and KeyLenghth and not using setPassword()
$cipher->setKeyLength(256); $cipher->setBlockLength(128); with no notable changes.
I have little experience in decrypting and ciphers, so I digged some info on the C# code used. Looking at the Rijndael class here https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.rijndael?view=netframework-4.8. I tried several things with not much ideas on what I should look. I don't even know if there is possible to use Phpseclib to decrypt data made by this C# code.
Thanks to every people who could give me some guidance.
