Is TRIPLE DES(ENCRYPTION ALGORTHM) a modern cipher or a block cipher?

Answer 1

Triple DES (3DES) is first and foremost a block cipher. It could also be considered a modern cipher, if you consider classical ciphers such as the Caesar and Playfair ciphers to NOT be modern.

I would say both are correct, though if given the choice, I would choose "block" over "modern"

Answer 2

The question does not make sense - these are not two properties that can be used in an either/or question.

The opposite of "block cipher" is a "stream cipher". The opposite of "modern" is "obsolete".

Tripple DES is simply DES used 3 times. DES is a block cipher - not a stream cipher. DES is about half a century old, so some consider it obsolete. There are various known cryptographic attacks against it, although none are known that can break it easily. It is also possible to build a special-purpose device for breaking DES using a brute-force attack. It would produce results reasonably fast (in a matter of hours) and its cost will not be prohibitive for a well-funded organization.

While 3DES is much stronger than plain DES, it is nowadays recommended that it is gradualy replaced with the much more secure AES cipher.