Triple DES Modes
Triple ECB (Electronic Code Book)
This variant of Triple DES works exactly the same way as the ECB mode of DES.
This is the most commonly used mode of operation.
Triple CBC (Cipher Block Chaining)
This method is very similar to the standard DES CBC mode.
As with Triple ECB, the effective key length is 168 bits and keys are used in the same manner, as described above, but the chaining features of CBC mode are also employed.
The first 64-bit key acts as the Initialization Vector to DES.
Triple ECB is then executed for a single 64-bit block of plaintext.
The resulting ciphertext is then XORed with the next plaintext block to be encrypted, and the procedure is repeated.
This method adds an extra layer of security to Triple DES and is therefore more secure than Triple ECB, although it is not used as widely as Triple ECB.