CAB340 CRYPTOGRAPHY 2020 SEMESTER
2 EXAM WITH CORRECT QUESTIONS AND
CORRECTLY WELL DEFINED ANSWERS
LATEST ALREADY GRADED A+ 2025 – 2026
Redundancy - ANSWERS-The difference in a language
between the amount of info that is carried per char and the
amount that could be carried per char.
Redundancy equation - ANSWERS-D = Hmax - r
Hmax = _____ __ - ANSWERS-Hmax = log2 L where L is the
number of characters in an alphabet.
Unicity distance equation - ANSWERS-N ≈ H(K) / D
Perfect secrecy equation - ANSWERS-Pr(x, y) = Pr(x) * Pr(y)
Ciphertext-only attack - ANSWERS-Cryptanalysis attack
where the attacker has access only to a set of ciphertexts.
, Chosen-plaintext attack - ANSWERS-Cryptanalysis attack
where the attacker can obtain the cipher text equivalent of
some plaintext which can be selected by the attacker.
Chosen-ciphertext attack - ANSWERS-Cryptanalysis attack
where the attacker chooses some ciphertext and obtains its
decryption/plaintext under an unknown key.
Kerckhoff's Principle - ANSWERS-The cryptanalyst has
complete knowledge of the cipher - the decryption key is
the only thing unknown to the cryptanalyst. This principle is
a reasonable assumption to make.
Transposition Cipher - ANSWERS-A cipher that rearranges
the order of characters in a message. Their positions are
permuted.
Substitution Cipher - ANSWERS-A method of encryption and
decryption in which each letter in the alphabet is replaced
by another. Their values are permuted.
Polyalphabetic substitution cipher - ANSWERS-A type of
cipher text that uses multiple mappings from plaintext to
2 EXAM WITH CORRECT QUESTIONS AND
CORRECTLY WELL DEFINED ANSWERS
LATEST ALREADY GRADED A+ 2025 – 2026
Redundancy - ANSWERS-The difference in a language
between the amount of info that is carried per char and the
amount that could be carried per char.
Redundancy equation - ANSWERS-D = Hmax - r
Hmax = _____ __ - ANSWERS-Hmax = log2 L where L is the
number of characters in an alphabet.
Unicity distance equation - ANSWERS-N ≈ H(K) / D
Perfect secrecy equation - ANSWERS-Pr(x, y) = Pr(x) * Pr(y)
Ciphertext-only attack - ANSWERS-Cryptanalysis attack
where the attacker has access only to a set of ciphertexts.
, Chosen-plaintext attack - ANSWERS-Cryptanalysis attack
where the attacker can obtain the cipher text equivalent of
some plaintext which can be selected by the attacker.
Chosen-ciphertext attack - ANSWERS-Cryptanalysis attack
where the attacker chooses some ciphertext and obtains its
decryption/plaintext under an unknown key.
Kerckhoff's Principle - ANSWERS-The cryptanalyst has
complete knowledge of the cipher - the decryption key is
the only thing unknown to the cryptanalyst. This principle is
a reasonable assumption to make.
Transposition Cipher - ANSWERS-A cipher that rearranges
the order of characters in a message. Their positions are
permuted.
Substitution Cipher - ANSWERS-A method of encryption and
decryption in which each letter in the alphabet is replaced
by another. Their values are permuted.
Polyalphabetic substitution cipher - ANSWERS-A type of
cipher text that uses multiple mappings from plaintext to
