What encryption should be used in encoding and how does it affect key and initialisation vectors?

Question

Hi,

I'm getting my head around encryption and how encoding affects generation of the keys and initialization vectors.

I'm working with a TripleDESCryptoServiceProvider which requires 24 byte key and 8 byte initialization vector using ASCII encoding. If i decide to use a different encoding , how will this affect generation of the key and the initialization vector?

Which encoding should I be using instead UTF8/16/32?

Thank you

Answer 1

The encryption parameters are completely unrelated to your choice of encoding. Encryption parameters are always defined in terms of bytes. Encoding is concerned with translating characters to bytes and bytes back to characters. The only place they "collide" is using passwords to generate encryption keys. You should use a class designed specifically to do this, like Rfc2898DeriveBytes.

Most of the times I see ASCII encoding used the programmer would have been better served using UTF8 encoding. UTF8 encoding encodes and decodes ASCII characters exactly the same way as ASCII encoding, but it also correctly and efficiently encodes all the rest of the Unicode. Use ASCII encoding if you need to generate an Exception when a non-ASCII character is encountered.

Answer 2

I'm no expert, but, TripleDES is no longer considered secure enough. Microsoft's recommendation is to use AES 256 bit and above. I don't think the text encoding affects the strength of the encryption, only the length of the "plain text" key and IV.