●●●●● ●●●● ●●0 Use in Cryptanalysis ●●● ●●●● o key concept-monoalphabetic substitution ciphers do not change relative letter frequencies o discovered by Arabian scientists in gth century o calculate letter frequencies for ciphertext o compare counts/plots against known values o for monoalphabetic must identify each letter o tables of common double/triple letters help COMP4690. HKBUCOMP4690, HKBU 16 Use in Cryptanalysis ⚫ key concept - monoalphabetic substitution ciphers do not change relative letter frequencies ⚫ discovered by Arabian scientists in 9th century ⚫ calculate letter frequencies for ciphertext ⚫ compare counts/plots against known values ⚫ for monoalphabetic must identify each letter ⚫ tables of common double/triple letters help