ECES Certified Encryption Specialist From EC Council –
Questions With Correct Solutions
Mono-Alphabet Cipher Correct Answer - -this type of cipher substitutes
one character of ciphertext for one character of plaintext
Ceasar Cipher Correct Answer - -each letter is shifted a fixed number of
spaces to the left or right in the alphabet
-the shifting is the "key"
-the shift is often called the "alphabet" being used'
Atbash Correct Answer - -hebrew code which substitutes the first letter
of the alphabet for the last and the second letter for the second to last, etc.
-this basically reverses the alphabet
-this was used by hebrew scribes copying the book of Jeremiah
Affine Cipher Correct Answer - -is any single-substitution alphabet
cipher where each letter is mapped to some numerical value, permuted with
some simple mathematical function, and then converted back to a letter
-basic formula is ax+b (mod M)
Rot 13 Cipher Correct Answer - -single alphabet substitution cipher
which consists of all characters being rotated 13 characters through the
alphabet
Scytale Cipher Correct Answer - - cylinder tool used by the Greeks but
mostly attributed to the Spartans
-physical cylinder used to encrypted messages
-turning produced different ciphertexts
,-the writer wrapped parchments around the rod to create the message and
the reader uses a rod of the same diameter to read the message
Single Subsitution - Weaknesses Correct Answer - -this became apparent
because more people learned how to read causing it to lose it's security
-languages appeared to have letter and word frequency so people were able to
start figuring the ciphers out
Multi-Alphabet Substitutions Correct Answer - -this was introduced to
make single-substitution stronger by rotating through the keys adding a +1,
+2, etc.
-this dealt with the letter and word frequency problem making them harder to
break
Cipher Disk Correct Answer - -invented by Leon Alberti in 1466
-each time a disk was turned, the disk would produce a produce a new cipher
text from plaintext
Vigenere Cipher Correct Answer - -this was the most widely known
poly-alphabetic cipher
-it was invented by Giovan Battista Bellaso in 1553
-this was a method of encrypting alphabetic text by using a series of different
mono-alphabet ciphers based on the letters of a keyword
-this was misattributed to Blaise de Vigenere
Friedrich Kasiski Correct Answer - -this guy was the first person to
publish a general attack on the Vigenere Cipher in 1863
Playfair Cipher Correct Answer - -invented in 1854 by Charles
Wheatstone and named after Lord Playfair
-encrypts two letters rather than one
,-more complex but not more secure, proving the point that the more complex
doesn't automatically prove more secure
ADFGX Cipher Correct Answer - -used by the German Army during WWI
-invented by Colonel Fritz Nebel in 1918
-this is a transposition cipher
-used a modified polybius square, a single columnar transposition and a 36
letter alphabet
Homophonic Substitution Correct Answer - -was one of the earlier
attempts to make substitution ciphers more robust by masking letter
frequencies
-plaintext letters map to more than one cipher text symbol
-used symbols instead of characters to make it even more confusing
-message is hidden in unrelated text
-the sender and recipient have pre-arranged to use some pattern taking
certain letters from the message Correct Answer - Null cipher
Book Cipher Correct Answer - -both parities agree to use a particular
book as the basis
-simplest implementation is to send coordinate for words
-numerous variations
Rail Fence Ciphers Correct Answer - -most widely known transposition
cipher
-take down the message you want to encrypt and alter each letter on a
different row
"Attackatdawn" is written as A t c a d w
, taktan
-to decrypt the recipient must write it out on rows
The Enigma Machine Correct Answer - -in WWII the Germans made use
of an electro-mechanical rotor based cipher system
-machine that was designed so that when the operator pressed a key, the
encrypted cipher text for the plain text was different every time
SIGABA, British Type X Correct Answer - -Allied cipher machines used in
WWII
Hash Function Correct Answer - -function that takes a variable-size
input m and returns a fixed string
-expressed mathematically as h=H(m)
-input can be any length
-output has a fixed length
-one way
-collision free
MAC (HMAC) Correct Answer - -added when a hash used for message
integrity is not enough
-adds a key to a hash to improve integrity
-uses a block cipher in CBC mode to improve integrity
TIGER Correct Answer - -192 bit hash function
-designed by Ross Anderson and Eli Biham
-designed using the Merkle-Damgard construction
Questions With Correct Solutions
Mono-Alphabet Cipher Correct Answer - -this type of cipher substitutes
one character of ciphertext for one character of plaintext
Ceasar Cipher Correct Answer - -each letter is shifted a fixed number of
spaces to the left or right in the alphabet
-the shifting is the "key"
-the shift is often called the "alphabet" being used'
Atbash Correct Answer - -hebrew code which substitutes the first letter
of the alphabet for the last and the second letter for the second to last, etc.
-this basically reverses the alphabet
-this was used by hebrew scribes copying the book of Jeremiah
Affine Cipher Correct Answer - -is any single-substitution alphabet
cipher where each letter is mapped to some numerical value, permuted with
some simple mathematical function, and then converted back to a letter
-basic formula is ax+b (mod M)
Rot 13 Cipher Correct Answer - -single alphabet substitution cipher
which consists of all characters being rotated 13 characters through the
alphabet
Scytale Cipher Correct Answer - - cylinder tool used by the Greeks but
mostly attributed to the Spartans
-physical cylinder used to encrypted messages
-turning produced different ciphertexts
,-the writer wrapped parchments around the rod to create the message and
the reader uses a rod of the same diameter to read the message
Single Subsitution - Weaknesses Correct Answer - -this became apparent
because more people learned how to read causing it to lose it's security
-languages appeared to have letter and word frequency so people were able to
start figuring the ciphers out
Multi-Alphabet Substitutions Correct Answer - -this was introduced to
make single-substitution stronger by rotating through the keys adding a +1,
+2, etc.
-this dealt with the letter and word frequency problem making them harder to
break
Cipher Disk Correct Answer - -invented by Leon Alberti in 1466
-each time a disk was turned, the disk would produce a produce a new cipher
text from plaintext
Vigenere Cipher Correct Answer - -this was the most widely known
poly-alphabetic cipher
-it was invented by Giovan Battista Bellaso in 1553
-this was a method of encrypting alphabetic text by using a series of different
mono-alphabet ciphers based on the letters of a keyword
-this was misattributed to Blaise de Vigenere
Friedrich Kasiski Correct Answer - -this guy was the first person to
publish a general attack on the Vigenere Cipher in 1863
Playfair Cipher Correct Answer - -invented in 1854 by Charles
Wheatstone and named after Lord Playfair
-encrypts two letters rather than one
,-more complex but not more secure, proving the point that the more complex
doesn't automatically prove more secure
ADFGX Cipher Correct Answer - -used by the German Army during WWI
-invented by Colonel Fritz Nebel in 1918
-this is a transposition cipher
-used a modified polybius square, a single columnar transposition and a 36
letter alphabet
Homophonic Substitution Correct Answer - -was one of the earlier
attempts to make substitution ciphers more robust by masking letter
frequencies
-plaintext letters map to more than one cipher text symbol
-used symbols instead of characters to make it even more confusing
-message is hidden in unrelated text
-the sender and recipient have pre-arranged to use some pattern taking
certain letters from the message Correct Answer - Null cipher
Book Cipher Correct Answer - -both parities agree to use a particular
book as the basis
-simplest implementation is to send coordinate for words
-numerous variations
Rail Fence Ciphers Correct Answer - -most widely known transposition
cipher
-take down the message you want to encrypt and alter each letter on a
different row
"Attackatdawn" is written as A t c a d w
, taktan
-to decrypt the recipient must write it out on rows
The Enigma Machine Correct Answer - -in WWII the Germans made use
of an electro-mechanical rotor based cipher system
-machine that was designed so that when the operator pressed a key, the
encrypted cipher text for the plain text was different every time
SIGABA, British Type X Correct Answer - -Allied cipher machines used in
WWII
Hash Function Correct Answer - -function that takes a variable-size
input m and returns a fixed string
-expressed mathematically as h=H(m)
-input can be any length
-output has a fixed length
-one way
-collision free
MAC (HMAC) Correct Answer - -added when a hash used for message
integrity is not enough
-adds a key to a hash to improve integrity
-uses a block cipher in CBC mode to improve integrity
TIGER Correct Answer - -192 bit hash function
-designed by Ross Anderson and Eli Biham
-designed using the Merkle-Damgard construction
