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Correct OPTION is (c) HELLO

The best explanation: Autokey cipher is a TYPE of POLY alphabetic substitution which uses vigenere table for making SUBSTITUTIONS in the plain text after generating key USING plain text. Using the table we find the plain text to be “HELLO”.

Correct choice is (a) true

The best explanation: Keyword CIPHER is less SECURE than Autokey cipher. It is due to the fact that keyword cipher is MONO alphabetic and thus can be cracked USING frequency analysis. But Autokey cipher being a poly alphabetic cipher cannot be cracked using this METHOD.

Correct OPTION is (a) Vigenere CIPHER

The best explanation: AUTOKEY cipher like vigenere cipher uses vigenere table in order to encrypt the plain text. The difference in these cipher is the USAGE of the keyword.

The CORRECT answer is (d) Additive cipher

The best explanation: In POLY alphabetic cipher each symbol of plain text is REPLACED by a DIFFERENT cipher text REGARDLESS of its occurrence. Out of the given options only additive cipher is not a poly alphabetic cipher.

The CORRECT answer is (C) vigenere table

Easy EXPLANATION - Encryption of plain TEXT in AUTOKEY cipher is done using the same table which is used for encryption in vigenere cipher. It is known as vigenere table.

The correct option is (b) POLY-ALPHABETIC cipher

Easiest EXPLANATION - Autokey cipher is a substitution cipher. It falls under the category of poly alphabetic cipher as it uses multiple substitutions at different positions in order to cipher the plain TEXT.

Correct option is (c) an algorithm that performs encryption or decryption

Explanation: Cipher is an algorithm for PERFORMING encryption or decryption. In cryptography, a set of defined steps are followed to GENERATE ciphers. These are necessary to prevent a DATA breach.

Correct choice is (b) KTSWNQRXM

The explanation is: For encrypting plain text choose the FIRST letter of plain text (i.e. A) in the first horizontal row. Then find the first letter of key (i.e. K) in the column obtained in the first STEP. Finally, choose the leftmost letter of the row (i.e. K) obtained in the PREVIOUS step. So the CORRESPONDING cipher text is “KTSWNQRXM”.

The CORRECT answer is (c) SELFQEXBHM

For explanation: For encrypting plain text choose the first letter of plain text (i.e. S) in the first horizontal row. Then find the first letter of key (i.e. K) in the column OBTAINED in the first STEP. Finally, choose the leftmost letter of the row (i.e. S) obtained in the PREVIOUS step. So the CORRESPONDING cipher text is “SELFQEXBHM”.

The correct CHOICE is (B) False

Explanation: Beaufort cipher is DIFFERENT from variant beaufort cipher. Variant beaufort cipher is a variant of beaufort cipher.

Right choice is (C) SAVEUS

The explanation is: The process of DECRYPTION and ENCRYPTION are exactly the same in beaufort cipher. So the corresponding plain text WOULD be “SAVEUS”.

Correct OPTION is (a) True

To explain: Beaufort cipher is an EXAMPLE of reciprocal cipher. So that is why the process of DECRYPTION is exactly same as that of encryption in beaufort cipher.

Correct CHOICE is (b) vigenere cipher

Easiest explanation - Beaufort cipher is a variant of vigenere cipher. The difference is that beaufort cipher uses TABULA recta in a DIFFERENT manner for ENCRYPTION.

The correct OPTION is (d) they USE the same table for ENCRYPTION, but in a DIFFERENT manner

The best I can explain: Beaufort CIPHER is a variation of vigenere cipher. They use the same table i.e. tabula recta for encryption but the table is used in a different manner.

Right answer is (c) TABULA recta

Explanation: Encryption of plain text in BEAUFORT cipher is DONE by making USE of tabula recta. The same table is ALSO used for encryption in vigenere cipher and running key cipher.

Right ANSWER is (B) poly-alphabetic cipher

To explain: Beaufort cipher is a SUBSTITUTION cipher. It falls under the category of poly alphabetic cipher as it USES MULTIPLE substitutions at different positions in order to cipher the plain text.

Correct choice is (a) RABBIT

To explain: Encryption in GRONSFELD cipher TAKES place by shifting the letters of the plain text by a number GIVEN by the numeric key. So by APPLYING the REVERSE of this method, we get the deciphered text to be “RABBIT”.

Correct OPTION is (b) EOIPVLVIQ

Explanation: Encryption in GRONSFELD cipher takes place by shifting the letters of the plain TEXT by a number given by the NUMERIC key. So by applying this method, we get the CIPHERED text to be “EOIPVLVIQ”.

The CORRECT CHOICE is (a) TCQJPWQHSA

The best I can explain: Encryption in gronsfeld cipher takes place by shifting the letters of the PLAIN text by a number GIVEN by the numeric KEY. So by applying this method, we get the ciphered text to be “TCQJPWQHSA”.

The correct choice is (b) ABROAD

Best explanation: Encryption in gronsfeld cipher takes place by shifting the letters of the PLAIN TEXT by a NUMBER GIVEN by the numeric KEY. So by applying the reverse of this method, we get the deciphered text to be “ABROAD”.

Right choice is (a) True

To explain: In gronsfeld CIPHER we shift the LETTERS of the PLAIN text on the BASIS of the key value. So it BECOMES a more complex version of the caesar cipher and thus harder to crack.

The correct option is (b) vigenere cipher

To explain: GRONSFELD cipher is a variation of vigenere cipher. The DIFFERENCE is that vigenere cipher USES an alphabetical KEY whereas the key of gronsfeld cipher consists of numbers.

Right ANSWER is (c) gronsfeld CIPHER

To explain: Ciphers like RUNNING key cipher, VIGENERE cipher, TRITHEMIUS cipher etc. makes use of tabula recta. Whereas gronsfeld cipher does not require tabula recta for encryption of plain text.

Right option is (a) GRONSFELD cipher

To explain: Gronsfeld cipher is a variation of vigenere cipher. The DIFFERENCE is that vigenere cipher uses an ALPHABETICAL key whereas gronsfeld cipher uses NUMERIC key.

Correct answer is (c) caesar CIPHER

Easy explanation - In gronsfeld cipher we shift the LETTERS of the PLAIN text on the BASIS of the key value. So it becomes a modified version of the caesar cipher.

The correct answer is (b) It SHIFTS the letters of plain text on the basis of KEY value

The best explanation: Encryption of plain text in gronsfeld CIPHER is DONE by shifting the letters of plain text on the basis of key value. So it is similar to CAESAR cipher.

Correct choice is (b) POLY-ALPHABETIC cipher

To EXPLAIN: Gronsfeld cipher is a SUBSTITUTION cipher. It falls under the category of poly alphabetic cipher as it uses multiple substitutions at different positions in ORDER to cipher the plain text.

The CORRECT option is (b) it can only be used to encrypt hebrew alphabet

The best I can EXPLAIN: Atbash CIPHER was originally built to encrypt hebrew alphabet. But it can be used to encrypt any TYPE of alphabets.

The correct choice is (a) NZL

Explanation: ATBASH cipher replaces each alphabet of the plain text with a CORRESPONDING letter which we can SEE in the table below.

Correct choice is (B) HVXIVG

The EXPLANATION is: Atbash cipher REPLACES each alphabet of the plain TEXT with a corresponding letter which we can see in the table below.

The correct answer is (b) False

The EXPLANATION is: ATBASH cipher is a very weak cipher. It can be easily BROKEN without even knowing the exact technique which has been used for encryption. We can just ASSUME the ciphered text to be a substitution cipher in order to crack it.

The correct answer is (a) True

The best I can EXPLAIN: Affine cipher is more secure as compared to pigpen cipher. Atbash cipher is a special CASE of affine cipher and can be CRACKED WITHOUT even knowing which TECHNIQUE has been used for encryption.

The correct choice is (d) atbash cipher

Best EXPLANATION: Atbash cipher is the only MONO alphabetic SUBSTITUTION cipher out of the GIVEN options. All the REMAINING options fall under the category of poly alphabetic cipher.

Correct option is (d) atbash cipher

For explanation: Atbash cipher is the weakest cipher out of the given OPTIONS. This is because it is a SIMPLE MONO ALPHABETIC substitution cipher with almost no security. It can be cracked WITHOUT even knowing which technique has been used for encryption.

Correct option is (C) hebrew alphabet

Easy explanation - ATBASH CIPHER was originally built to encrypt hebrew alphabet. But it can be used to encrypt any type of alphabets.

The CORRECT answer is (a) atbash cipher

The best I can EXPLAIN: Out of the given options only atbash cipher does not require a KEY for ENCRYPTION. Atbash cipher is an example of a substitution cipher.

Correct option is (c) ZEYQCBROCM

Explanation: VIGENERE CIPHER is a type of POLY ALPHABETIC substitution which uses vigenere table for MAKING substitutions in the plain text. Using the table we find the solution to be ZEYQCBROCM.

Right choice is (b) vigenere CIPHER

Explanation: In transposition cipher and mono alphabetic cipher the number of LETTERS remain same in ciphered and deciphered TEXT. But in POLY alphabetic cipher the number of letters are different. So here as vigenere cipher is the only poly alphabetic cipher so it will be the answer.

The CORRECT option is (c) INDIA

Best explanation: VIGENERE cipher is a type of POLY alphabetic substitution which uses vigenere table for making substitutions in the plain text. Using the table we find the plain text to be “INDIA”.

Right option is (a) true

The best I can EXPLAIN: KEYWORD cipher is less secure than vigenere cipher. It is due to the fact that keyword cipher is mono alphabetic and THUS can be cracked using frequency ANALYSIS. But vigenere cipher being a poly alphabetic cipher cannot be deciphered using this method.

Right option is (a) 26 rows and 26 COLUMNS

The best explanation: ENCRYPTION of plain TEXT using vigenre cipher is done by making use of VIGENERE table. It consists of 26 rows and 26 columns which have alphabets written 26 times. These are SHIFTED towards left after each row.

The correct CHOICE is (d) Multiplicative cipher

Easiest EXPLANATION - In POLY alphabetic cipher each symbol of plain text is replaced by a different cipher text REGARDLESS of its occurrence. Out of the given options only multiplicative cipher is not a poly alphabetic cipher.

Right answer is (a) a substitution BASED cipher which uses multiple substitution at DIFFERENT positions

The best I can EXPLAIN: Poly alphabetic cipher is a type of substitution cipher. It uses multiple substitution at different positions in order to cipher the plain TEXT.

Correct option is (c) vigenere SQUARE

To explain: Encryption of plain text USING vigenre CIPHER is DONE by making use of vigenere table. It is also known as vigenere square.