Plaintext: Message before encoding
Ciphertext: Message that has gone through a cryptographic algorithm to encrypt it.
Cipher: Encryption Algorithm, it’s basically a set of (usually mathematical) rules on how to encrypt and decrypt
Cryptographic Key: Very large number (Usually binary)
One-Way Function: A function that easily produces and output, which does not lead back to the input
Reversability: The ability to undo the encryption
Nonce: Number only used once, a counter for example
IV (Initialization Vector): Is a random number to fill the block size. It’s an add-on used to get different encryption for the same messages.
In short:
Confusion is about complexity in the relationship between plaintext and ciphertext.
Diffusion is about how changes in plaintext affect the ciphertext broadly.
This relies on the secrecy of the encryption algorithm to not find the original message.