Certified Encryption Specialist Exam Questions with Correct Answers Graded A+
Cryptography - Answers The science of altering communication so that it cannot be understood without
having a key.
Caesar Cipher - Answers Simple cipher that uses shifting letters.
Atbash - Answers Used by Hebrews, cipher that reverses the alphabet.
ROT13 - Answers Cipher that rotate or shifts by 13 letters.
Scytale - Answers Cylinder tool used to encrypt and decrypt plaintext using a cloth or piece of leather
wrapped around a rod.
Vigenere Cipher - Answers Most common multi-alphabetic cipher.
Symmetric Encryption - Answers Same key is used to Encrypt and Decrypt plaintext.
Also known as Single Key Encryption.
Diffusion - Answers Changes to one letter in plaintext changes multiple characters of the ciphertext.
Confusion - Answers Makes the relationship between the statistical frequencies of the ciphertext and
the actual key as complex as possible.
Avalanche - Answers A small change in the input yields a large change in the output.
Complete Avalanche - Answers A change in one bit of the plaintext affecting all bits in the ciphertext.
Kerckhoffs Principle - Answers The crypto system should be secure if everything about the system,
except the key, is publicly known.
Substitution - Answers Changing some part of the plaintext for some matching part of the ciphertext.
Transposition - Answers Swapping of blocks of ciphertext.
Binary ADD - Answers Stack both binary numbers; If both numbers are 1 then it's 1, otherwise it's 0.
Binary OR - Answers Stack both binary numbers; If either is a 1 then it's 1, otherwise it's 0.
Binary XOR - Answers Stack both binary numbers; If their is a 1 in one number but not the other then it's
a 1, otherwise its 0.
This is reversible.
Block Cipher - Answers Encrypts the information in blocks.
Stream Cipher - Answers Encrypts the information one bit at a time.
,DES - Answers Data Encryption Standard
DES (Characteristics) - Answers Made by IBM in 1970's.
64 bit Block Cipher.
56 Bit Key.
Uses Feistal Cipher.
Feistal Function - Answers 64 Bits split Left and Right, Round function to one side, XORed with the other
side then sides are Transposed or switched.
Then continued for a set number of rounds.
Unbalanced Feistal Function - Answers Same as Feistal but the 64 bits are not equally split.
Skipjack uses the Unbalanced Feistal Function.
3DES - Answers Uses Data Encryption Standard with a key bundle. Three 56 bit keys are used to encrypt
with key 1, decrypt with key 2 and then encrypt with key 3.
DESx - Answers Same as Data Encryption Standard but the plaintext is XORed with the key then
encrypted.
Is not more secure since the key space is still the same.
Whitening - Answers The process of XORing in an additional key at any time in the encryption process.
AES - Answers Advanced Encryption Standard
AES (Characteristics) - Answers Replaced DES in 2001.
Capable of Key sizes 128 bit, 192 bit, and 256 bit.
128 bit Block Size.
Developed by Joan Daemen and Vincent Rimen.
Designated as FIPS 197.
Based on substitution-permutation matrix.
Blowfish (Characteristics) - Answers Capable of Key sizes 32 to 448 bits.
64 bit Block Size.
Developed by Bruce Schneier.
Based on Feistal Cipher using 16 rounds.
, Serpent (Characteristics) - Answers Capable of Key sizes 128 bit, 192 bit, and 256 bit.
128 bit Block Size.
Developed by Ross Anderson, Eli Biham, and Lars Knudson.
Based on substitution-permutation similar to AES
Designed to execute all operations in parallel.
Twofish (Characteristics) - Answers Capable of Key sizes up to 256 bits.
128 bit Block Size.
Developed by Bruce Schneier, John Kelsey, Doug Whiting, David Wagner, Chris Hall, and Neils Ferguson.
Skipjack (Characteristics) - Answers Key size of 80 bits.
64 bit Block Size.
Developed by NSA.
Designed to be on a cipher chip.
Based on Unbalanced Feistal Cipher.
Controversial, as the decryption key was held in escrow which would allow law enforcement to decrypt
without the owners permission.
IDEA - Answers International Data Encryption Algorithm
IDEA (Characteristics) - Answers Key size of 128 bits.
64 bit Block Size.
Developed by James Massey and Xuejia Lai.
ECB - Answers Electronic Code Book
ECB (Characteristics) - Answers Each block of plaintext is encrypted separately.
The same plaintext will always result in the same ciphertext.
CBC - Answers Cipher-Block Chaining
CBC (Characteristics) - Answers Each block of plaintext is XORed with the previous ciphertext block
before encryption.
PCBC - Answers Propagating Cipher-Block Chaining
Cryptography - Answers The science of altering communication so that it cannot be understood without
having a key.
Caesar Cipher - Answers Simple cipher that uses shifting letters.
Atbash - Answers Used by Hebrews, cipher that reverses the alphabet.
ROT13 - Answers Cipher that rotate or shifts by 13 letters.
Scytale - Answers Cylinder tool used to encrypt and decrypt plaintext using a cloth or piece of leather
wrapped around a rod.
Vigenere Cipher - Answers Most common multi-alphabetic cipher.
Symmetric Encryption - Answers Same key is used to Encrypt and Decrypt plaintext.
Also known as Single Key Encryption.
Diffusion - Answers Changes to one letter in plaintext changes multiple characters of the ciphertext.
Confusion - Answers Makes the relationship between the statistical frequencies of the ciphertext and
the actual key as complex as possible.
Avalanche - Answers A small change in the input yields a large change in the output.
Complete Avalanche - Answers A change in one bit of the plaintext affecting all bits in the ciphertext.
Kerckhoffs Principle - Answers The crypto system should be secure if everything about the system,
except the key, is publicly known.
Substitution - Answers Changing some part of the plaintext for some matching part of the ciphertext.
Transposition - Answers Swapping of blocks of ciphertext.
Binary ADD - Answers Stack both binary numbers; If both numbers are 1 then it's 1, otherwise it's 0.
Binary OR - Answers Stack both binary numbers; If either is a 1 then it's 1, otherwise it's 0.
Binary XOR - Answers Stack both binary numbers; If their is a 1 in one number but not the other then it's
a 1, otherwise its 0.
This is reversible.
Block Cipher - Answers Encrypts the information in blocks.
Stream Cipher - Answers Encrypts the information one bit at a time.
,DES - Answers Data Encryption Standard
DES (Characteristics) - Answers Made by IBM in 1970's.
64 bit Block Cipher.
56 Bit Key.
Uses Feistal Cipher.
Feistal Function - Answers 64 Bits split Left and Right, Round function to one side, XORed with the other
side then sides are Transposed or switched.
Then continued for a set number of rounds.
Unbalanced Feistal Function - Answers Same as Feistal but the 64 bits are not equally split.
Skipjack uses the Unbalanced Feistal Function.
3DES - Answers Uses Data Encryption Standard with a key bundle. Three 56 bit keys are used to encrypt
with key 1, decrypt with key 2 and then encrypt with key 3.
DESx - Answers Same as Data Encryption Standard but the plaintext is XORed with the key then
encrypted.
Is not more secure since the key space is still the same.
Whitening - Answers The process of XORing in an additional key at any time in the encryption process.
AES - Answers Advanced Encryption Standard
AES (Characteristics) - Answers Replaced DES in 2001.
Capable of Key sizes 128 bit, 192 bit, and 256 bit.
128 bit Block Size.
Developed by Joan Daemen and Vincent Rimen.
Designated as FIPS 197.
Based on substitution-permutation matrix.
Blowfish (Characteristics) - Answers Capable of Key sizes 32 to 448 bits.
64 bit Block Size.
Developed by Bruce Schneier.
Based on Feistal Cipher using 16 rounds.
, Serpent (Characteristics) - Answers Capable of Key sizes 128 bit, 192 bit, and 256 bit.
128 bit Block Size.
Developed by Ross Anderson, Eli Biham, and Lars Knudson.
Based on substitution-permutation similar to AES
Designed to execute all operations in parallel.
Twofish (Characteristics) - Answers Capable of Key sizes up to 256 bits.
128 bit Block Size.
Developed by Bruce Schneier, John Kelsey, Doug Whiting, David Wagner, Chris Hall, and Neils Ferguson.
Skipjack (Characteristics) - Answers Key size of 80 bits.
64 bit Block Size.
Developed by NSA.
Designed to be on a cipher chip.
Based on Unbalanced Feistal Cipher.
Controversial, as the decryption key was held in escrow which would allow law enforcement to decrypt
without the owners permission.
IDEA - Answers International Data Encryption Algorithm
IDEA (Characteristics) - Answers Key size of 128 bits.
64 bit Block Size.
Developed by James Massey and Xuejia Lai.
ECB - Answers Electronic Code Book
ECB (Characteristics) - Answers Each block of plaintext is encrypted separately.
The same plaintext will always result in the same ciphertext.
CBC - Answers Cipher-Block Chaining
CBC (Characteristics) - Answers Each block of plaintext is XORed with the previous ciphertext block
before encryption.
PCBC - Answers Propagating Cipher-Block Chaining
