# Difference Between Stream Ciphers and Block Ciphers

Stream Ciphers Vs. Block Ciphers: In this tutorial, we will learn about the key differences between stream ciphers and block ciphers in Cryptography. By Monika Sharma Last updated : May 24, 2023

The **Stream ciphers and the Block ciphers** both are a type of encryption technology that differs by how the plain text is converted into ciphertext. It should be noted that both the stream ciphers and the block ciphers are a type of symmetric-key cryptography technique.

The main difference between the two is that in Stream cipher, the plain text is taken letter by letter and is encrypted into the corresponding ciphertext (example: Caeser cipher), whereas, in the block ciphers, we divide the plain text into blocks of fixed size. These blocks are considered at once and encrypted into the corresponding ciphertext.

## Difference Between Stream Cipher and Block Cipher

The following are the key difference between stream cipher and block cipher:

Characteristic | Stream Cipher | Block cipher |
---|---|---|

Method of encryption(Definiton) |
The plain text is converted into ciphertext by considering the plain text letter by letter. | The plain text is divided into blocks of fixed size. For encryption, one block is considered at a time and is encrypted into ciphertext. |

Length of the plain text |
In the stream cipher, the length of the text is not a major issue as the encryption is done letter by letter. | In the block cipher, the length of the text needs to be of a length so that the blocks of fixed length can be formed. If the length of the plain text does not fit in, padding is done. |

Number of Bits used for encryption and decryption |
Uses 8 bits | Can use blocks of following length: 64 bits, 128 bits, 52 bits, etc. |

Complexity of encryption process |
The complexity of encryption is much higher in stream cipher as compared to block cipher. | Compared to that of a stream cipher, the encryption process of block ciphers is easier to perform. |

Complexity of decryption process |
The process of decryption is easy in stream ciphers. | It is comparatively harder to perform decryption in block ciphers. |

Level of security offered |
The security level offered by stream cipher is quite low as the encryption is hard but the decryption is easy. | The security level offered by block cipher is high, because of the encryption being an easy process and the decryption being the hard one. |

Algorithm modes used in encryption |
ECB: Electronic Code Book CBC: Cipher Block Chaining |
CFB: Cipher Feedback OFB: Output Feedback |

Examples(Encryption techniques) |
Caesar cipher, Vernam cipher, One time pad cipher | DES (Data Encryption Standard), AES (Advanced Encryption Standard), Playfair cipher, Hill cipher |

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- Introduction to Cryptography
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