Code and cipher
- 1. Codes and Ciphers By, Chirag Umraniya 160280116107 Mayank Timbal 160280116104 Matin Shaikh 160280116092 Karmishth Tandel 160280116102
- 2. • Codes generally substitute different length strings of character in the output, while Ciphers generally substitute the same number of characters as are input. • There are exceptions and some cipher systems may use slightly more, or fewer, characters when output versus the number that were input. Definition of Code and Cipher
- 3. How it works? • Codes operated by substituting according to a large codebook which linked a random string of characters or numbers to a word or phrase. • When using a Cipher the original information is known as plaintext, and the encrypted form as ciphertext. The ciphertext message contains all the information of the plaintext message, but is not in a format readable by a human or computer without the proper mechanism to decrypt it.
- 4. Some popular examples of Codes and Ciphers
- 5. 1. Morse Code Information: • Founded in 1836. • By American artist Samuel Morse, with the American physicist Joseph Henry, and Alfred Vail. • Note: The name "Morse code" is misleading because, this is in fact a cipher not a code. All the letters of the alphabet, number from 0-9 and some punctuation marks have been replaced by dots, dashes or short and long beeps.
- 6. Working: • Messages could be sent long-distance electrically using the Morse code via the telegraph. • It was not used for concealing message, but transmitting information as a series of clicks, tones or lights. • A skilled observer or listener can directly understand the information without any equipment. • A basic understanding is required by pilots and air traffic controllers. • SOS, the most common distress signal, recognized internationally is depicted as three dots, three dashes and three dots. Simple example:
- 7. 2. Caesar Shift Cipher • This particular cipher has been named after Julius Caesar, since he used it himself. • In G cipher, A becomes G, B becomes H and so on. In Y Cipher, A becomes Y and so on. • This particular cipher is not very difficult to decipher and hence secret messages do not remain secret for long. • But on the bright side this particular cipher has been used as the basis for creation of more complex ciphers. • Example:
- 8. 3. Enigma Code • The Germans used this sophisticated cipher during the Second World War. • It involved using an Enigma machine, which is similar to the type writer. • All Germans had the same Enigma machine and the initial wheel configuration of the machine was communicated to all the teams. When a letter was pressed on the machine, a cipher letter lit up on the screen. • It got even more difficult when the wheel rotated after certain number of letters, so that the cipher kept on changing. • There could be over one hundred trillion possible configurations and hence was difficult to decipher Enigma.
- 9. 4. Public-Key Crytography • Public Key Cryptography is modern and is made of two keys – the private and the public key. • The public key is a large number everyone can get. • The private key is made of two numbers (apart from 1 and the number itself). • These two numbers are multiplied together and can produce the public key. For example, the public key is 1764, the private key can be 36 and 49 (36×49=1764). • Without the private key, the code cannot be deciphered.
- 10. 5. Transposition Cipher • This particular cipher was used during American Civil War and World War I to communicate sensitive messages. • The letters of the alphabet are rearranged based on pre-determined key or rule. • It could be that all the words in the message are written backwards, or every pair of letters is swapped. If the rearrangement rule is complex, it might seem very difficult to decipher, however, with modern algorithms on the computer, it can be easily deciphered. • For example: “the yellow car belongs to him” can become “eht wolley rac sgnoleb ot mih” when written backwards.
- 11. 6. Book Cipher • This particular cipher involves the use of some key, essentially in a book. • Both the parties should have the same book and the same edition to successfully decipher the code. • Locations in the book are used to replace the plain text of the message. • The ease of decoding depends on the how well the key has been chosen. • Also the book should be inconspicuous and of the genre which is similar to the type of messages required to be sent.
- 12. 7. Pigpen Cipher • This is also referred to as Tic-Tac-Toe Cipher, and is fairly simple substitution cipher. • The letters of the alphabet are replaced by fragments of a geometrical grid. • Although its origin cannot be ascertained, it goes back to the 18th century. • The grid and the dots are the core elements of the cipher. • The alphabets are arranged in two grids, followed by two Xs.
- 13. 8. Steganography • This involves the concealment of a message, image or a file in another message, image or file. • The first record of its use is in 1499. Text could be written using invisible ink between visible lines of a text. • The benefit of this type is that it does not arouse suspicion like an encrypted message would. • There are various ways in which this can be done – physical, digital, social and using puzzles as well. • Digital images are used largely for hiding messages as bits. • Various modern techniques are available by which steganography can be performed.
- 14. 9. Playfair Cipher • Here we come to the last one on the list of types of codes and ciphers. • The Playfair cipher is also known as the Playfair Square. • It was invented by Charles Wheatstone in 1854, but is named after the person who promoted its use. • In this type of cipher, pairs of letters are encrypted instead of single letters. • Thus it is harder to decipher. It creates 600 possible digraphs as compared to 26 monographs.
- 15. Thank You