Cipher modes

There are different cipher modes; most symmetric keys use a block cipher and can encrypt a large amount of data quicker than asymmetric encryption. Let us look at these in turn:

• Stream cipher: A stream cipher (https://searchsecurity.techtarget.com/definition/cipher) is a method of encrypting text (to produce ciphertext (https://whatis.techtarget.com/definition/ciphertext)) in which a cryptographic key and algorithm (https://whatis.techtarget.com/definition/algorithm) are applied to each binary digit (https://whatis.techtarget.com/definition/bit-binary-digit) in a data stream, one bit at a time. In this mode, only one key is used. It uses symmetric encryption but is not commonly used today as it is easy to crack.
• Block cipher: A block cipher is where a block of data is taken and then encrypted, for example 128 bits of data are encrypted at a time. This is the method used today as it is much faster than a stream cipher.

Stream versus block cipher analogy

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