Difference Between Block Cipher and Stream Cipher

Block Cipher Vs. Stream Cipher: Explore What is the Difference Between Block Cipher and Stream Cipher?

Both the Stream Cipher and Block Cipher belong to a part of the symmetric key cipher. Both of these are basically the methods that one can use for converting any given set of plain texts into a Cipher text. There’s a major difference between Block Cipher and Stream Cipher. The Block Cipher primarily performs the conversion of plain text into a cipher text by taking one block of plain text at a given time. On the other hand, the Stream Cipher can perform this kind of conversion by taking a single byte of plain text at a given time.

Now let us understand the difference between them both.

Difference Between Block Cipher and Stream Cipher

Stream Cipher

Definition

It is a type of encryption that performs the conversion of a plain text by taking a single block at a given time.

It is a type of encryption that performs the conversion of plain text by taking a byte of plain text at a time.

Principle

It makes use of both the diffusion and confusion principles for the conversion (used later in encryption).

It only makes use of the confusion principle to carry out the process of conversion.

Conversion of Bits

The Block Cipher converts one block of plain text at a given time. Thus, it is capable of converting comparatively more bits than the Stream Cipher. As a result, it converts about 64 bits at a time or more.

The Stream Cipher, on the other hand, is capable of converting a minimum of 8 bits at any given time.

Algorithm

The Block Cipher makes use of the ECB (Electronic Code Block) and the CBC (Cipher Block Chaining) algorithms to perform the encryption of plain text.

The Stream Cipher, on the other hand, makes use of the Output Feedback (OFB) and the Cipher Feedback (CFB) algorithms to perform the process of conversion.

Decryption

The Block Cipher generally encrypts a combination of more bits. Thus, the process of decryption or reverse encryption becomes way more complex here as compared to the Stream Cipher.

The Stream Cipher, on the other hand, makes use of the process of XOR for encryption. One can easily reverse it to plain text at any given time.

Implementation

The primary implementation of the Block Cipher takes place in the Fiestal Cipher.

The main implementation of the Stream Cipher, on the other hand, takes place in the Vernam Cipher.

Complexity

The Block Cipher has a comparatively simple structure and design.

The Stream Cipher has a comparatively more complicated and complex design of its own.

Speed

The Block Cipher is very slow as compared to the Stream Cipher.

The Stream Cipher, on the other hand, works comparatively much faster than the Block Cipher.

Working Techniques

The Block Cipher basically works on the techniques (of transportation) like the columnar transportation technique, the rail-fence technique, etc.

The Stream Cipher, on the other hand, works on various substitute techniques such as the Polygram Substitution Cipher, the Caesar Cipher, etc.

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