1. Monoalphabetic Cipher :
A monoalphabetic cipher is any cipher in which the letters of the plain text are mapped to cipher text letters based on a single alphabetic key. Examples of monoalphabetic ciphers would include the Caesar-shift cipher, where each letter is shifted based on a numeric key, and the atbash cipher, where each letter is mapped to the letter symmetric to it about the center of the alphabet.
2. Polyalphabetic Cipher :
A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case.
Difference Between Monoalphabetic Cipher and Polyalphabetic Cipher :
|SR.NO||Monoalphabetic Cipher||Polyalphabetic Cipher|
|1||Monoalphabetic cipher is one where each symbol in plain text is mapped to a fixed symbol in cipher text.||Polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets.
|2||The relationship between a character in the plain text and the characters in the cipher text is one-to-one.||The relationship between a character in the plain text and the characters in the cipher text is one-to-many.|
|3||Each alphabetic character of plain text is mapped onto a unique alphabetic character of a cipher text.||Each alphabetic character of plain text can be mapped onto ‘m’ alphabetic characters of a cipher text.|
|4||A stream cipher is a monoalphabetic cipher if the value of key does not depend on the position of the plain text character in the plain text stream.||A stream cipher is a polyalphabetic cipher if the value of key does depend on the position of the plain text character in the plain text stream.|
|5||It includes additive, multiplicative, affine and monoalphabetic substitution cipher.||It includes autokey, Playfair, Vigenere, Hill, one-time pad, rotor, and Enigma cipher.
|6||It is a simple substitution cipher.||It is multiple substitutions cipher.|
|7||Monoalphabetic Cipher is described as a substitution cipher in which the same fixed mappings from plain text to cipher letters across the entire text are used.||Polyalphabetic Cipher is described as substitution cipher in which plain text letters in different positions are enciphered using different cryptoalphabets.|
|8||Monoalphabetic ciphers are not that strong as compared to polyalphabetic cipher.||Polyalphabetic ciphers are much stronger.|
Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.