Substitution and transposition ciphers are two categories of ciphers used in classical cryptography. Substitution and transposition differ in how chunks of the message are handled by the encryption process. Substitution ciphers Substitution ciphers encrypt plaintext by changing the plaintext one piece at a time. The Caesar Cipher was an early substitution cipher. In the Caesar …
PKI Authorities consists of three different authorities that essentially make up a PKI system. These are the Registration Authority, Certification Authority and Certificate Directory. Registration Authority The jobs of the Registration Authority are to processes user requests, confirm their identities, and induct them into the user database. Certification Authority The tasks of a Certification Authority …
In cryptography, the known plaintext attack, or KPA, is an attack based on having samples of both the plaintext and corresponding encrypted or ciphertext for that information available. This information is used to conduct an analysis of the data in order to determine the secret key used to encrypt and decrypt the information. Historical ciphers …
The known ciphertext attack, or ciphertext only attack (COA) is an attack method used in cryptanalysis when the attacker has access to a given set of ciphertext(s). The attacker does not have access to corresponding cleartext in this method; however, COA is successful when correspdonding plaintext can be determined from a given set of ciphertext. …
Steganography has gained a significant amount of press over the past several years when the technique hit the press as a possible method that many of the terrorists involved with the 9/11 attacks used to plan the operation. Similar to the use of encryption, steganography techniques have become one of the basic methods that organizations …
Kerberos is a network authentication protocol which utilizes symmetric cryptography to provide authentication for client-server applications. Kerberos Standard Definition Kerberos is defined in RFC 1510 – The Kerberos Network Authentication Service (V5). Kerberos Architecture The core of Kerberos architecture is the KDC (Key Distribution Server). The KDC stores authentication information and uses it to securely …