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Difference between Block Cipher and Stream Cipher

  • Difficulty Level : Easy
  • Last Updated : 17 Nov, 2021

Prerequisite – Block cipher modes of operation 
Block Cipher and Stream Cipher belongs to the symmetric key cipher. These two block ciphers and stream cipher are the methods used for converting the plain text into ciphertext. 

The main difference between a Block cipher and a Stream cipher is that a block cipher converts the plain text into cipher text by taking plain text’s block at a time. While stream cipher Converts the plain text into cipher text by taking 1 byte of plain text at a time. 
 

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Let’s see the difference between them: 

S.NOBlock CipherStream Cipher
1.Block Cipher Converts the plain text into cipher text by taking plain text’s block at a time.Stream Cipher Converts the plain text into cipher text by taking 1 byte of plain text at a time.
2.Block cipher uses either 64 bits or more than 64 bits.While stream cipher uses 8 bits.
3.The complexity of block cipher is simple.While stream cipher is more complex.
4.Block cipher Uses confusion as well as diffusion.While stream cipher uses only confusion.
5.In block cipher, reverse encrypted text is hard.While in-stream cipher, reverse encrypted text is easy.
6.The algorithm modes which are used in block cipher are ECB (Electronic Code Book) and CBC (Cipher Block Chaining).The algorithm modes which are used in stream cipher are CFB (Cipher Feedback) and OFB (Output Feedback).
7.Block cipher works on transposition techniques like rail-fence technique, columnar transposition technique, etc.While stream cipher works on substitution techniques like  Caesar cipher, polygram substitution cipher, etc.
8.Block cipher is slow as compared to a stream cipher.While stream cipher is fast in comparison to block cipher.
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