●●●●● ●●●● ●●0 Cryptanalysis ●●● ●●●● To exploit the characteristics of the cipher algorithm to attem pt to deduce a specific plaintext or to deduce the key ciphertext only o only know the ciphertext, the most difficult known plaintext o know some plaintext, ciphertext] pairs, to deduce the key chosen plaintext Plaintext chosen by cryptanalyst, together with its corresponding ciphertext generated with the key chosen ciphertext o ciphertext chosen by cryptanalyst, together with its corresponding decrypted plaintext generated with the key e chosen text chosen plaintext& chosen ciphertext COMP4690. HKBUCOMP4690, HKBU 7 Cryptanalysis ⚫ To exploit the characteristics of the cipher algorithm to attempt to deduce a specific plaintext or to deduce the key ⚫ ciphertext only ⚫ only know the ciphertext, the most difficult! ⚫ known plaintext ⚫ know some {plaintext, ciphertext} pairs, to deduce the key ⚫ chosen plaintext ⚫ Plaintext chosen by cryptanalyst, together with its corresponding ciphertext generated with the key ⚫ chosen ciphertext ⚫ ciphertext chosen by cryptanalyst, together with its corresponding decrypted plaintext generated with the key ⚫ chosen text ⚫ chosen plaintext & chosen ciphertext