History of DES Essay

DES was proposed in 1975 and approved in 1977 as a federal information processing standard. It was criticized by the people who felt that it’s 56 key lengths to be insecure. In spite of this, DES remained a strong encryption algorithm until mid 1990. In the year 1998 summer, the insecurity of DES was demonstrated when a $ 250,000 computer which was built by the electronic frontier foundation decrypted a DES-encoded message in 56 hours. This was improved in the 1999 to 2002 hours through a combination of 100,000 networked personal computers and the EFF machine. DES remains a de facto standard unless a substitute is found (Landau, 2000, p. 341). A certified DES is obtained from the National Institute of Standards and Technology (NIST). This Advanced Encryption Standard (AES) works in three key lengths: 128, 192, and 256 bits. The publication of DES indicated a new era in cryptography. The development in the community of public cryptographers was enhanced by having an algorithm availability of study that the national security agent certified to be secure (Landau, 2000, p. 341). The (DES) Data Encryption Standard. A system that encrypts quickly but is essentially what is impossible to break is all what cryptographers have always wanted. Public key systems have captured the imagination of mathematicians because of their reliance on elementary number theory. Public key algorithms are used for establishing a key because they are too slow to be used for most data transmissions. Private key system does the encryption because they are typically faster than public key ones (Landau, 2000, p. 341). The data Encryption Standard (DES) workhorse uses private key algorithm besides relying on cryptographic design principles that predate public key. The RC4 in web browsers and the relatively insecure cable TV signal encryption are an exception to DES. DES is the most widely used public cryptosystem in the world. It is the cryptographic algorithm which is used by banks for electronic funds transfer. It is also used for the protection of civilian satellite communications. Still, a variant of DES is used for UNIX password protection. There are three operation of the DES which involves XOR, substitution and permutation. The DES is an interrelated block cipher and a cryptosystem on a block of symbols that sequentially repeats an internal function which is called a round. It encrypts data by the use of a primitive that operates on a block of symptoms of moderate size. Self invert ability is also essential to enable one of the objects to encrypt and decrypt. When encrypting ordinary text, DES begins by grouping the text into 64 bit block. A number of operations are performed by the DES on each block (Landau, 2000, p. 343). The transformation of how the block is to be carried out is determined by a single key of 56 bits. DES iterates sixteen identical rounds of mixing; each round of DES uses a 48-bit sub key. The DES begins with an initial permutation P and ends with its inverse. The permutations are of minor cryptographic implications but forms part of the official algorithm. The selection of sub keys starts by splitting the 56-bit key into two 28-bit halves and rotating each half one or two bits; either one bit in rounds 1, 2, 9, and 16 or two bits otherwise. The two halves are put back together and then 48 particular bits are chosen and put in order (Landau, 2000, p. 343). Attacks of DES The selection of DES was followed by protests in which case some of the researchers appeared to object to the algorithm small key space. Investors in the key public cryptography claimed that a DES encoded message could be broken in about a day by a $ 20 million machine made up of a million specially designed VLSI capable of searching one key per microsecond while working in parallel. The use of a meet in the middle attack to break a four round version of DES did not extend past seven rounds (Landau, 2000, p. 345). This is evidence that, for all these attacks none of them posed a serious threat to the DES. Other attacks on the DES were performed to poke harder to the innards of DES. This brought anomalies which led to the first attacks that were seen to be more theoretically better than exhaustive search. The attacks were against the block structure system and the need of all block-structured cryptosystems needed to be designed to be secure against differential and linear cryptanalysis. There is a strong attack to DES which is differential cryptanalysis. This is apparently known to the algorithms designers. In order to design a secure cryptosystems, there is a need for a mixture of well known principles, some theorems and the presence of some magic. Attacks on a cryptosystem fall into two categories which are passive attacks and active attacks. The passive attacks are the ones which adversely monitors the communication channel. They are usually easier to mount although they yield less. The active attacks have the adversary transmitting messages to obtain information (Landau, 2000, p. 342). The aim of the attackers is to determine the plaintext from the cipher text which they capture. A more successful attack will determine the key and thus compromise a whole set of messages. By designing their algorithms, cryptographer’s help to resist attacks such as cipher text only attack whose adversary has access to the encrypted communications. The known plain text attack which has its adversary has some plain text and its corresponding cipher text. The third attack which can be avoided is the chosen text attack and its adversary chooses the plain text for encryption or decryption. The plain text chosen by the adversary depends on the cipher text received from the previous requests (Landau, 2000, p. 342).