What is the Difference Between a Block Cipher and a Stream Cipher?

Before comparing the difference between a block cipher and a stream cipher I would like to explain a bit what each of these terms means. So, what exactly is a cipher?

A cipher is simply an algorithm for performing encryption and decryption using a series of well-defined steps. Ciphers encrypt text by concealing its readability and meaning. Now, what is a block cipher?

A block cipher is defined as a method of encrypting text where a cryptographic key and an algorithm are applied to a block of data, for example, 64 contiguous bits, at once as a group rather than to one bit at a time. Finally, what is a stream cipher?

A stream cipher is simply a method of encrypting text where a cryptographic key and an algorithm are applied to each binary digit in a data stream, one bit at a time.

Difference between stream cipher and block cipher

  • Stream cipher keys and algorithms are applied to each binary digit, one bit at a time whereas block cipher keys and algorithm are applied to a block of data.
  • Stream ciphers are less time consuming compared to block ciphers.
  • Stream ciphers are faster than block cipher, this is due to the fact that they encrypt a bit at a time.
  • Stream ciphers do not use chaining modes of operation whereas block ciphers heavily use chaining modes of operation. Commonly known as block cipher modes of operation.
  • Hardware implementation is easier using stream cipher than in a block cipher.
  • A software implementation is easier using block cipher than in a stream cipher.
  • The best example of a stream cipher is the one-time pad whereas Data encryption standard (DES) is the best example of a block cipher.
  • Block ciphers are more code intensive compared to stream ciphers.
  • Stream ciphers are mainly used in SSL technology while block ciphers are mainly used in database and file encryption applications.

From the above comparison between stream ciphers vs block cipher, we can conclude that the main difference between stream cipher and block cipher is that the block cipher encrypts and decrypts a block of text at a time while stream ciphers encrypt and decrypts the text by taking the one byte of the text at a time.

Now I want to hear from you.

What do you think of block ciphers vs stream cipher?

Or maybe I missed an important difference between a block cipher and stream cipher.

Either way, let me know by leaving a comment below.

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