Secure symmetric algorithms include the commonly used aes (advanced encryption standard) which replaced the older des (data encryption standard) The most obvious and, in principle at least, simplest way of cracking a code is to steal the codebook through bribery, burglary, or raiding parties — procedures sometimes glorified by the phrase practical cryptography — and this is a weakness for both codes and ciphers, though codebooks are generally larger and used longer than cipher keys. Each key pair consists of a public key and a corresponding private key
[8] stream ciphers encrypt the digits (typically bytes), or letters (in substitution ciphers) of a message one at a time Data encryption key (dek) used to encrypt the underlying data [9] block ciphers take a number of bits and encrypt them in a single unit.
[1] until recent decades, it has been the story of what might be called classical cryptography — that is, of methods of encryption that use pen and paper, or perhaps simple mechanical aids. Six common block cipher modes of operation for encrypting in cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity [2] it has an entity authentication mechanism, based on the x.509 system
