Decrypt AES256 value created in Salesforce using C #

Question

By running the following Apex code in Salesforce, I encrypt the string:

public static String getEncryptedData() { Blob cryptoKey = Crypto.generateAesKey(256); String dataToEncrypt = 'Test string'; Blob encryptedData = Crypto.encryptWithManagedIV('AES256', cryptoKey, Blob.valueOf(dataToEncrypt)); return EncodingUtil.base64Encode(encryptedData); } 

Assuming this implementation is correct, I need to decrypt it in C #. I have the following, but I see that the error "Filling is invalid and cannot be deleted." (An example of a key and an encrypted string value, of course):

 private string Decrypt(string encryptedbase64Password) { RijndaelManaged aes256 = new RijndaelManaged(); aes256.KeySize = 256; aes256.Mode = CipherMode.CBC; aes256.Padding = PaddingMode.PKCS7; aes256.BlockSize = 128; // Salesforce.com stores the first 16 bytes as the IV // Extract first 16 bytes as IV, the rest as the Key string keyAndIv = "Ii7oSjjWuhp6J6/hj/wmivqx1h3N2HzJ2ByJOy1n89E="; // sample from SFDC // hard coded for this example: encryptedbase64Password = "hRVlbM79aEQi8Tz7JJIL7CEhSxZAJvCh8Ni6ORP1C55+qbJzjDshBYBjyP12/zT2"; byte[] allBytes = Convert.FromBase64String(keyAndIv); byte[] iv = new byte[16]; Array.Copy(allBytes, 0, iv, 0, iv.Length); byte[] key = new byte[allBytes.Length - 16]; Array.Copy(allBytes, 16, key, 0, key.Length); aes256.Key = key; aes256.IV = iv; ICryptoTransform decrypto = aes256.CreateDecryptor(); byte[] encryptedbytes = Convert.FromBase64String(encryptedbase64Password); byte[] decryptedText = decrypto.TransformFinalBlock(encryptedbytes, 0, encryptedbytes.Length); string result = Convert.ToBase64String(decryptedText); return result; } 

What am I doing wrong?

Answer 1

The custom "Doublehead Software" posted the right solution on Salesforce development boards . CryptoStream seems to handle the fill problem correctly. decision:

 string plaintext; byte[] Key = Convert.FromBase64String("Ii7oSjjWuhp6J6/hj/wmivqx1h3N2HzJ2ByJOy1n89E="); string encryptedbase64Password = "hRVlbM79aEQi8Tz7JJIL7CEhSxZAJvCh8Ni6ORP1C55+qbJzjDshBYBjyP12/zT2"; byte[] IV = new byte[16]; byte[] phase = Convert.FromBase64String(encryptedbase64Password); Array.Copy(phase, 0, IV, 0, IV.Length); byte[] cipherText = new byte[phase.Length - 16];; Array.Copy(phase, 16, cipherText, 0, cipherText.Length); using (AesManaged aesAlg = new AesManaged()) { aesAlg.KeySize = 256; aesAlg.Mode = CipherMode.CBC; aesAlg.Padding = PaddingMode.PKCS7; aesAlg.Key = Key; aesAlg.IV = IV; // Create a decryptor to perform the stream transform. // NOTE: This is the difference between my original solution and the correct one. ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV); // Create the streams used for decryption. using (MemoryStream msDecrypt = new MemoryStream(cipherText)) { 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(); } } } }