Lec 6 in Computer and Data Security

2.3.3 Homophonic Substitution Cipher

Homophonic substitution ciphers maps each character (a) of the plaintext alphabet into a set of ciphertext elements f(a) called homophone. Beale , and High order are example of homophonic ciphers.


• BEALE CIPHERS:

A plaintext message M=m1 m2... .... is encrypted as C = c1 c1 ... ...... where ci is picked at random from the set of homophones f(mi).
Example: English letters are enciphered as integers (0 - 99), a group of integers are assigned to a letter proportional to the relative frequency of the letter, as follows:
2.3.3 Homophonic Substitution Cipher

Homophonic substitution ciphers maps each character (a) of the plaintext alphabet into a set of ciphertext elements f(a) called homophone. Beale , and High order are example of homophonic ciphers.


• BEALE CIPHERS:

A plaintext message M=m1 m2... .... is encrypted as C = c1 c1 ... ...... where ci is picked at random from the set of homophones f(mi).
Example: English letters are enciphered as integers (0 - 99), a group of integers are assigned to a letter proportional to the relative frequency of the letter, as follows:























M= P L A I N P I L 0 T C= 91 44 56 65 59 33 08 76 28 78

Homophonic substitution ciphers are more complicated than simple substitution ciphers, but still do not obscure all of the statistical properties of the plaintext language.























M= P L A I N P I L 0 T C= 91 44 56 65 59 33 08 76 28 78

Homophonic substitution ciphers are more complicated than simple substitution ciphers, but still do not obscure all of the statistical properties of the plaintext language.