XEX mode
A block cipher mode that XORs input and output with a mask that depends on the block's position.
XEX (XOR-Encrypt-XOR) was presented by Phillip Rogaway in 2004 as a way to make a block cipher tweakable. Each block is XORed with a mask derived from the key and a tweak, such as the block's position, encrypted, and XORed again. Blocks do not chain as they do in CBC, so one block can be processed on its own.
XTS, which IEEE 1619 standardised in 2007 for disk encryption, builds on the same idea. The same plaintext at the same position still gives the same ciphertext, so patterns remain visible, but only where the position is identical.