cipher feedback

A block cipher mode that enhances ECB mode by chaining together the blocks of cipher text it produces and operating on plaintext segments of variable length less than or equal to the block length. [FP081] (See: block cipher, [SP38A].)

Tutorial: This mode operates by using the previously generated ciphertext segment as the algorithm's input (i.e., by "feeding back" the cipher text) to generate an output block, and then combining (exclusive OR-ing) that output block with the next plaintext segment (block length or less) to form the next ciphertext segment.