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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 |