its confidentiality and integrity are preserved. That is, the data remains secret to those who do not posses the secret key, and modifications to the cipher text can be detected during decryption. Two of the most popular symmetric ciphers are the Data Encryption Standard (DES) and the International Data Encryption Algorithm (IDEA). The DES algorithm operates on blocks of 64 bits at a time using a key length of 56 bits. The 64 bits are permuted according to the value of the key, and so encryption with two keys that differently in one bit produces two completely different cipher texts. The most popular mode of DES is called Cipher Block Chaining (CBC) mode, where output from previous block are mixed with the plaintext of each block. The first block is mixed with the plaintext of each block. The block uses a special value called the Initialization Vector.Despite its size and rapid growth, the Web is still in its infancy. So is the software industry. We are just beginning to learn how to develop secure software, and we are beginning to understand that for our future, if it is to be online, we need to incorporate security into the basic underpinnings of everything we develop....
