C # AES-256 Encryption

Question

I use RijndaelManaged to create a simple encryption / decryption utility. This works great, but I'm trying to integrate it with another program created on Unix (Oracle). My problem is that for all the smaller input strings, I get the same encrypted hexadecimal code as the Unix code, but for longer strings, half of my encrypted hexadecimal value is the same, but the other half is different:

Unix Output:

012345678901234 - 00984BBED076541E051A239C02D97117 0123456789012345678 - A0ACE158AD8CF70CEAE8F76AA27F62A30EA409ECE2F7FF84F1A9AF50817FC0C4 

Windows output (my code):

 012345678901234 - 00984BBED076541E051A239C02D97117 (same as above) 0123456789012345678 - A0ACE158AD8CF70CEAE8F76AA27F62A3D9A1B396A614DA2C1281AA1F48BC3EBB (half exactly same as above) 

My windows code is:

 public string Encrypt(byte[] PlainTextBytes, byte[] KeyBytes, string InitialVector) { byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector); RijndaelManaged SymmetricKey = new RijndaelManaged(); SymmetricKey.Mode = CipherMode.ECB; SymmetricKey.Padding = PaddingMode.PKCS7; ICryptoTransform Encryptor = SymmetricKey.CreateEncryptor(KeyBytes, InitialVectorBytes); MemoryStream MemStream = new MemoryStream(); CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write); CryptoStream.Write(PlainTextBytes, 0, PlainTextBytes.Length); CryptoStream.FlushFinalBlock(); byte[] CipherTextBytes = MemStream.ToArray(); MemStream.Close(); CryptoStream.Close(); return ByteToHexConversion(CipherTextBytes); } 

Unix Code (PL / SQL):

 FUNCTION Encrypt_Card (plain_card_id VARCHAR2) RETURN RAW AS num_key_bytes NUMBER := 256/8; -- key length 256 bits (32 bytes) encrypted_raw RAW (2000); -- stores encrypted binary text encryption_type PLS_INTEGER := -- total encryption type DBMS_CRYPTO.ENCRYPT_AES256 + DBMS_CRYPTO.CHAIN_CBC + DBMS_CRYPTO.PAD_PKCS5; key_bytes_raw RAW(64) :=my_hex_key; BEGIN encrypted_raw := DBMS_CRYPTO.ENCRYPT ( src => UTL_I18N.STRING_TO_RAW (plain_card_id, 'AL32UTF8'), typ => encryption_type, key => key_bytes_raw ); RETURN encrypted_raw; EXCEPTION WHEN OTHERS THEN dbms_output.put_line (plain_card_id || ' - ' || SUBSTR(SQLERRM,1,100) ); RETURN HEXTORAW ('EEEEEE'); 

The only difference I see is the use of PKCS5 and PCKS7. But .NET does not have PCKS5.

Answer 1

What abc said, and also it looks like you don't have an IV (initialization vector) in your PL / SQL code at all.

The fact that the first part is the same is related to different modes (ECB and CBC). ECB encrypts each block separately, while CBC uses the previous block when encrypting the next.

What happens here is that since you are using CBC and not setting IV, IV is all zeros.
This means that the first block of ECB encryption and CBC encryption will be the same.
(Since A XOR 0 = A).

You must make sure that you use the same encryption mode on both systems, and if you select CBC, make sure that you use the same IV.

Answer 2

In the other case, you use ECB in one case and CBC.