Question

One symbol could be substituted with a key using substitution cipher.

a. True

b. False

Answer 1

Hi ,

Statement: One symbol could be substituted with a key using substitution cipher.

Answer: B) False

Explanation: A substitution cipher is a complex code that involves the use of a pre-set key which unlocks the cipher and makes it readable. The only way to break the cipher is through a brute force attack which is time consuming or through possession of the key. Therefore the above statement is false.

Thanks.

Answer 2

Answer is option ( a ) :

True.That is to say, a symbol was substituted for an alphabet and could only be read with the key.Ciphers are codes applied obscure the real meaning of a sentence or of a phrase.

Anybody can create a Ciphers and have been in use from the style of the Romans. One of the most famous ciphers is considered that belonged to  Caesar’s cipher subsequent to the Roman emperor Julius Caesar.

A very common cipher is the substitution type of cipher which employs a repeated substitution technique and strategy to prepare the code unbreakable.

In order to make it difficult to crack, the only ways to break the code are by means of using the key to the cipher or by application of brute-force attack, the intruder tries all possible passwords and checks which one of them gives the correct plaintext results.

A brute-force attack is also called detailed key search.  For breaking ciphers using brute-force attacks, very fast specially designed supercomputers are normally applied.