What Does Block Cipher Mean?
A block cipher is a symmetric cryptographic algorithm that operates on a fixed-size block of data using a shared, secret key. Plaintext is used during the encryption, and the resulting encrypted text is called a ciphertext. The same key is used for both the encryption of the plaintext and the decryption of the ciphertext.
Techopedia Explains Block Cipher
Block cipher encrypts/decrypts its input one block at a time instead of one bit at a time using a shared, secret key. The block is fixed in size; otherwise, padding is necessary. This algorithm is symmetric. During encryption, it uses the shared key to transform its plaintext input into a cyphertext (encrypted text). During decryption, it uses the same key to transform the cyphertext back to the original plaintext. The length of the output is the same as the input.
