Difference between Monoalphabetic Cipher and Polyalphabetic Cipher
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. |
Last Updated :
02 Nov, 2020
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